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Android中常见的热门标签的流式布局的实现

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Android中常见的热门标签的流式布局的实现

2015-04-14 14:48 9999人阅读 评论(15) 收藏 举报
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目录(?)[+]

一、概述：
在日常的app使用中，我们会在android 的app中看见 热门标签等自动换行的流式布局，今天，我们就来看看如何

自定义一个类似热门标签那样的流式布局吧（源码下载在下面最后给出）

类似的自定义布局。下面我们就来详细介绍流式布局的应用特点以及用的的技术点：

1.流式布局的特点以及应用场景
    特点：当上面一行的空间不够容纳新的TextView时候，
    才开辟下一行的空间

　　原理图：

　　

    场景：主要用于关键词搜索或者热门标签等场景
2.自定义ViewGroup,重点重写下面两个方法

    1、onMeasure:测量子view的宽高，设置自己的宽和高

    2、onLayout:设置子view的位置

    onMeasure:根据子view的布局文件中属性，来为子view设置测量模式和测量值
    测量=测量模式+测量值；

    测量模式有3种：
    EXACTLY：表示设置了精确的值，一般当childView设置其宽、高为精确值、match_parent时，ViewGroup会将其设置为EXACTLY；
    AT_MOST：表示子布局被限制在一个最大值内，一般当childView设置其宽、高为wrap_content时，ViewGroup会将其设置为AT_MOST；
    UNSPECIFIED：表示子布局想要多大就多大，一般出现在AadapterView的item的heightMode中、ScrollView的childView的heightMode中；此种模式比较少见。
3.LayoutParams
    ViewGroup LayoutParams :每个 ViewGroup 对应一个 LayoutParams; 即 ViewGroup -> LayoutParams
    getLayoutParams 不知道转为哪个对应的LayoutParams ,其实很简单，就是如下：
    子View.getLayoutParams 得到的LayoutParams对应的就是 子View所在的父控件的LayoutParams;
    例如，LinearLayout 里面的子view.getLayoutParams ->LinearLayout.LayoutParams
    所以 咱们的FlowLayout 也需要一个LayoutParams，由于上面的效果图是子View的 margin，
    所以应该使用MarginLayoutParams。即FlowLayout->MarginLayoutParams

4.最后来看看实现的最终效果图：


二、热门标签的流式布局的实现：

1. 自定义热门标签的ViewGroup实现

　　根据上面的技术分析，自定义类继承于ViewGroup，并重写 onMeasure和onLayout等方法。具体实现代码如下：

[plain] view plaincopy
  1. package com.czm.flowlayout;  
  2.   
  3. import java.util.ArrayList;  
  4. import java.util.List;  
  5.   
  6. import android.content.Context;  
  7. import android.util.AttributeSet;  
  8. import android.view.View;  
  9. import android.view.ViewGroup;  
  10. /**  
  11.  *   
  12.  * @author caizhiming  
  13.  * @created on 2015-4-13  
  14.  */  
  15. public class XCFlowLayout extends ViewGroup{  
  16.   
  17.     //存储所有子View  
  18.     private List<List<View>> mAllChildViews = new ArrayList<>();  
  19.     //每一行的高度  
  20.     private List<Integer> mLineHeight = new ArrayList<>();  
  21.       
  22.     public XCFlowLayout(Context context) {  
  23.         this(context, null);  
  24.         // TODO Auto-generated constructor stub  
  25.     }  
  26.     public XCFlowLayout(Context context, AttributeSet attrs) {  
  27.         this(context, attrs, 0);  
  28.         // TODO Auto-generated constructor stub  
  29.     }  
  30.     public XCFlowLayout(Context context, AttributeSet attrs, int defStyle) {  
  31.         super(context, attrs, defStyle);  
  32.         // TODO Auto-generated constructor stub  
  33.     }  
  34.     @Override  
  35.     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
  36.         // TODO Auto-generated method stub  
  37.           
  38.         //父控件传进来的宽度和高度以及对应的测量模式  
  39.         int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);  
  40.         int modeWidth = MeasureSpec.getMode(widthMeasureSpec);  
  41.         int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);  
  42.         int modeHeight = MeasureSpec.getMode(heightMeasureSpec);  
  43.           
  44.         //如果当前ViewGroup的宽高为wrap_content的情况  
  45.         int width = 0;//自己测量的 宽度  
  46.         int height = 0;//自己测量的高度  
  47.         //记录每一行的宽度和高度  
  48.         int lineWidth = 0;  
  49.         int lineHeight = 0;  
  50.           
  51.         //获取子view的个数  
  52.         int childCount = getChildCount();  
  53.         for(int i = 0;i < childCount; i ++){  
  54.             View child = getChildAt(i);  
  55.             //测量子View的宽和高  
  56.             measureChild(child, widthMeasureSpec, heightMeasureSpec);  
  57.             //得到LayoutParams  
  58.             MarginLayoutParams lp = (MarginLayoutParams) getLayoutParams();  
  59.             //子View占据的宽度  
  60.             int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;  
  61.             //子View占据的高度  
  62.             int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;  
  63.             //换行时候  
  64.             if(lineWidth + childWidth > sizeWidth){  
  65.                 //对比得到最大的宽度  
  66.                 width = Math.max(width, lineWidth);  
  67.                 //重置lineWidth  
  68.                 lineWidth = childWidth;  
  69.                 //记录行高  
  70.                 height += lineHeight;  
  71.                 lineHeight = childHeight;  
  72.             }else{//不换行情况  
  73.                 //叠加行宽  
  74.                 lineWidth += childWidth;  
  75.                 //得到最大行高  
  76.                 lineHeight = Math.max(lineHeight, childHeight);  
  77.             }  
  78.             //处理最后一个子View的情况  
  79.             if(i == childCount -1){  
  80.                 width = Math.max(width, lineWidth);  
  81.                 height += lineHeight;  
  82.             }  
  83.         }  
  84.         //wrap_content  
  85.         setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width,  
  86.                 modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height);  
  87.         super.onMeasure(widthMeasureSpec, heightMeasureSpec);  
  88.     }  
  89.       
  90.     @Override  
  91.     protected void onLayout(boolean changed, int l, int t, int r, int b) {  
  92.         // TODO Auto-generated method stub  
  93.         mAllChildViews.clear();  
  94.         mLineHeight.clear();  
  95.         //获取当前ViewGroup的宽度  
  96.         int width = getWidth();  
  97.           
  98.         int lineWidth = 0;  
  99.         int lineHeight = 0;  
  100.         //记录当前行的view  
  101.         List<View> lineViews = new ArrayList<View>();  
  102.         int childCount = getChildCount();  
  103.         for(int i = 0;i < childCount; i ++){  
  104.             View child = getChildAt(i);  
  105.             MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();  
  106.             int childWidth = child.getMeasuredWidth();  
  107.             int childHeight = child.getMeasuredHeight();  
  108.               
  109.             //如果需要换行  
  110.             if(childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width){  
  111.                 //记录LineHeight  
  112.                 mLineHeight.add(lineHeight);  
  113.                 //记录当前行的Views  
  114.                 mAllChildViews.add(lineViews);  
  115.                 //重置行的宽高  
  116.                 lineWidth = 0;  
  117.                 lineHeight = childHeight + lp.topMargin + lp.bottomMargin;  
  118.                 //重置view的集合  
  119.                 lineViews = new ArrayList();  
  120.             }  
  121.             lineWidth += childWidth + lp.leftMargin + lp.rightMargin;  
  122.             lineHeight = Math.max(lineHeight, childHeight + lp.topMargin + lp.bottomMargin);  
  123.             lineViews.add(child);  
  124.         }  
  125.         //处理最后一行  
  126.         mLineHeight.add(lineHeight);  
  127.         mAllChildViews.add(lineViews);  
  128.           
  129.         //设置子View的位置  
  130.         int left = 0;  
  131.         int top = 0;  
  132.         //获取行数  
  133.         int lineCount = mAllChildViews.size();  
  134.         for(int i = 0; i < lineCount; i ++){  
  135.             //当前行的views和高度  
  136.             lineViews = mAllChildViews.get(i);  
  137.             lineHeight = mLineHeight.get(i);  
  138.             for(int j = 0; j < lineViews.size(); j ++){  
  139.                 View child = lineViews.get(j);  
  140.                 //判断是否显示  
  141.                 if(child.getVisibility() == View.GONE){  
  142.                     continue;  
  143.                 }  
  144.                 MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();  
  145.                 int cLeft = left + lp.leftMargin;  
  146.                 int cTop = top + lp.topMargin;  
  147.                 int cRight = cLeft + child.getMeasuredWidth();  
  148.                 int cBottom = cTop + child.getMeasuredHeight();  
  149.                 //进行子View进行布局  
  150.                 child.layout(cLeft, cTop, cRight, cBottom);  
  151.                 left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;  
  152.             }  
  153.             left = 0;  
  154.             top += lineHeight;  
  155.         }  
  156.           
  157.     }  
  158.     /**  
  159.      * 与当前ViewGroup对应的LayoutParams  
  160.      */  
  161.     @Override  
  162.     public LayoutParams generateLayoutParams(AttributeSet attrs) {  
  163.         // TODO Auto-generated method stub  
  164.           
  165.         return new MarginLayoutParams(getContext(), attrs);  
  166.     }  
  167. }  

2.相关的布局文件：

引用自定义控件：

[plain] view plaincopy
  1. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
  2.     xmlns:tools="http://schemas.android.com/tools"  
  3.     android:id="@+id/container"  
  4.     android:layout_width="match_parent"  
  5.     android:layout_height="match_parent" >  
  6.   
  7.     <com.czm.flowlayout.XCFlowLayout  
  8.         android:id="@+id/flowlayout"  
  9.         android:layout_width="match_parent"  
  10.         android:layout_height="match_parent" >  
  11.   
  12.     </com.czm.flowlayout.XCFlowLayout>  
  13.   
  14. </RelativeLayout>  

TextView的样式文件：

[plain] view plaincopy
  1. <?xml version="1.0" encoding="utf-8"?>  
  2. <shape xmlns:android="http://schemas.android.com/apk/res/android" >  
  3.     <solid android:color="#666666" />  
  4.     <corners android:radius="10dp" />  
  5.     <padding   
  6.         android:left="5dp"  
  7.         android:right="5dp"  
  8.         android:top="5dp"  
  9.         android:bottom="5dp"   
  10.         />  
  11.   
  12. </shape>  

三、使用该自定义布局控件类

最后，如何使用该自定义的热门标签控件类呢？很简单，请看下面实例代码：

[plain] view plaincopy
  1. package com.czm.flowlayout;  
  2.   
  3. import android.app.Activity;  
  4. import android.graphics.Color;  
  5. import android.os.Bundle;  
  6. import android.view.ViewGroup.LayoutParams;  
  7. import android.view.ViewGroup.MarginLayoutParams;  
  8. import android.widget.TextView;  
  9. /**  
  10.  *   
  11.  * @author caizhiming  
  12.  * @created on 2015-4-13  
  13.  */  
  14. public class MainActivity extends Activity {  
  15.   
  16.     private String mNames[] = {  
  17.             "welcome","android","TextView",  
  18.             "apple","jamy","kobe bryant",  
  19.             "jordan","layout","viewgroup",  
  20.             "margin","padding","text",  
  21.             "name","type","search","logcat"  
  22.     };  
  23.     private XCFlowLayout mFlowLayout;  
  24.     @Override  
  25.     protected void onCreate(Bundle savedInstanceState) {  
  26.         super.onCreate(savedInstanceState);  
  27.         setContentView(R.layout.activity_main);  
  28.           
  29.         initChildViews();  
  30.           
  31.     }  
  32.     private void initChildViews() {  
  33.         // TODO Auto-generated method stub  
  34.         mFlowLayout = (XCFlowLayout) findViewById(R.id.flowlayout);  
  35.         MarginLayoutParams lp = new MarginLayoutParams(  
  36.                 LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);  
  37.         lp.leftMargin = 5;  
  38.         lp.rightMargin = 5;  
  39.         lp.topMargin = 5;  
  40.         lp.bottomMargin = 5;  
  41.         for(int i = 0; i < mNames.length; i ++){  
  42.             TextView view = new TextView(this);  
  43.             view.setText(mNames[i]);  
  44.             view.setTextColor(Color.WHITE);  
  45.             view.setBackgroundDrawable(getResources().getDrawable(R.drawable.textview_bg));  
  46.             mFlowLayout.addView(view,lp);  
  47.         }  
  48.     }  
  49.   
  50. }  

四、源码下载

最后给出源码的下载：http://download.csdn.net/detail/jdsjlzx/8784571


这里引用另一个高手的实现，

摘要

新项目用到了一种全新布局————Android标签流式布局的功能，正好一直说给大家讲自定义控件的实现，今天就为大家讲一种android流式布局的实现。 
本文原创，转载请注明地址：http://blog.kymjs.com/

正文

在日常的app使用中，我们会在android 的app中看见热门标签等自动换行的流式布局，今天，我们就来看看如何自定义一个类似热门标签那样的流式布局吧（源码下载在下面最后给出）
OpenSourceLaboratory
这个控件并不是我实现的，代码是从网上搜流式布局找到的。我只是为大家讲解一下实现过程以及原理。

先看代码

<code class="language-java"><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="kd"><span class="kwd">class</span></span><span class="pln"> </span><span class="nc"><span class="typ">FlowLayout</span></span><span class="pln"> </span><span class="kd"><span class="kwd">extends</span></span><span class="pln"> </span><span class="n"><span class="typ">ViewGroup</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">    </span><span class="kd"><span class="kwd">private</span></span><span class="pln"> </span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="c1"><span class="com">//每个item纵向间距</span></span><span class="pln">    </span><span class="kd"><span class="kwd">private</span></span><span class="pln"> </span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="c1"><span class="com">//每个item横向间距</span></span><span class="pln">    </span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="nf"><span class="typ">FlowLayout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="typ">Context</span></span><span class="pln"> </span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="kd"><span class="kwd">super</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">);</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="nf"><span class="typ">FlowLayout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="typ">Context</span></span><span class="pln"> </span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="typ">AttributeSet</span></span><span class="pln"> </span><span class="n"><span class="pln">attrs</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="kd"><span class="kwd">super</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">context</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">attrs</span></span><span class="o"><span class="pun">);</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">setHorizontalSpacing</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">;</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="kd"><span class="kwd">public</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">setVerticalSpacing</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">float</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">pixelSize</span></span><span class="o"><span class="pun">;</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="nd"><span class="lit">@Override</span></span><span class="pln">    </span><span class="kd"><span class="kwd">protected</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">onMeasure</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">selfWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">resolveSize</span></span><span class="o"><span class="pun">(</span></span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">);</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingLeft</span></span><span class="o"><span class="pun">();</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingTop</span></span><span class="o"><span class="pun">();</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingRight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingBottom</span></span><span class="o"><span class="pun">();</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="c1"><span class="com">//通过计算每一个子控件的高度，得到自己的高度</span></span><span class="pln">        </span><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">            </span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">            </span><span class="n"><span class="typ">LayoutParams</span></span><span class="pln"> </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getLayoutParams</span></span><span class="o"><span class="pun">();</span></span><span class="pln">            </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">measure</span></span><span class="o"><span class="pun">(</span></span><span class="pln">                    </span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="o"><span class="pun">,</span></span><span class="pln">                            </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">width</span></span><span class="o"><span class="pun">),</span></span><span class="pln">                    </span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="o"><span class="pun">,</span></span><span class="pln">                            </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">height</span></span><span class="o"><span class="pun">));</span></span><span class="pln">            </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">            </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">            </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">            </span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">selfWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">                </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">                </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">                </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">            </span><span class="o"><span class="pun">}</span></span><span class="pln"> </span><span class="k"><span class="kwd">else</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">                </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln">            </span><span class="o"><span class="pun">}</span></span><span class="pln">        </span><span class="o"><span class="pun">}</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">wantedHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="n"><span class="pln">setMeasuredDimension</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">selfWidth</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">resolveSize</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">wantedHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">));</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="nd"><span class="lit">@Override</span></span><span class="pln">    </span><span class="kd"><span class="kwd">protected</span></span><span class="pln"> </span><span class="kt"><span class="kwd">void</span></span><span class="pln"> </span><span class="nf"><span class="pln">onLayout</span></span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">boolean</span></span><span class="pln"> </span><span class="n"><span class="pln">changed</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">l</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">t</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">r</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">b</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">myWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">r</span></span><span class="pln"> </span><span class="o"><span class="pun">-</span></span><span class="pln"> </span><span class="n"><span class="pln">l</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingLeft</span></span><span class="o"><span class="pun">();</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingTop</span></span><span class="o"><span class="pun">();</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getPaddingRight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="c1"><span class="com">//根据子控件的宽高，计算子控件应该出现的位置。</span></span><span class="pln">        </span><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">            </span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">            </span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getVisibility</span></span><span class="o"><span class="pun">()</span></span><span class="pln"> </span><span class="o"><span class="pun">==</span></span><span class="pln"> </span><span class="n"><span class="typ">View</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">GONE</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">                </span><span class="k"><span class="kwd">continue</span></span><span class="o"><span class="pun">;</span></span><span class="pln">            </span><span class="o"><span class="pun">}</span></span><span class="pln">            </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">            </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">            </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">            </span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">myWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">                </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">                </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">                </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">            </span><span class="o"><span class="pun">}</span></span><span class="pln">            </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">layout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">            </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln"></span><span class="o"><span class="pun">}</span></span></code>

从控件创建过程说起

  1. 当这个流式布局在被加载如内存并显示在屏幕上这一过程中，首先会调用view.measure(w,h)这个方法，表示测量view的宽度与高度，其中参数w与h分别表示这个控件的父控件的宽高。
  2. 在view.measure()方法的调用过程中又会调用view本身的一个回调方法,onMeasure()，这个是view自身的一个回调方法，用于让开发者在自定义View的时候重新计算自身的大小。一般会在这个方法中循环遍历，计算出这个控件的全部子孙控件的宽高。
  3. 在View的宽高计算完成以后，考虑将这个控件显示到屏幕的指定位置上，此时view的onLayout()方法会被调用。 一般同时会在这个方法中计算出全部子孙控件在这个控件中的位置。
    可能基本流程有些枯燥，接下来结合代码看看。

流布局的实现

看到onMeasure()方法中的这段： //通过计算每一个子控件的高度，得到自己的高度

<code class="language-java"><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">    </span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">    </span><span class="n"><span class="typ">LayoutParams</span></span><span class="pln"> </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getLayoutParams</span></span><span class="o"><span class="pun">();</span></span><span class="pln">    </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">measure</span></span><span class="o"><span class="pun">(</span></span><span class="pln">            </span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">widthMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="o"><span class="pun">,</span></span><span class="pln">                    </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">width</span></span><span class="o"><span class="pun">),</span></span><span class="pln">            </span><span class="n"><span class="pln">getChildMeasureSpec</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">heightMeasureSpec</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingBottom</span></span><span class="o"><span class="pun">,</span></span><span class="pln">                    </span><span class="n"><span class="pln">childLayoutParams</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">height</span></span><span class="o"><span class="pun">));</span></span><span class="pln">    </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">    </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">    </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">    </span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">selfWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln"> </span><span class="k"><span class="kwd">else</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln"></span><span class="o"><span class="pun">}</span></span></code>

首先通过循环，遍历这个控件的所有子控件，同时调用子控件的measure()方法，这时measure方法的两个参数是控件能给这个子控件的最大宽高(我们都知道的，子控件再大，显示的大小也不能比父控件还大)。这里getChildMeasureSpec()方法的作用是用来计算一个合适子视图的尺寸大小（宽度或者高度)，结合我们从子视图的LayoutParams所给出的MeasureSpec信息来获取最合适的结果。比如，如果这个View知道自己的大小尺寸（因为它本身的MeasureSpec的model为Exactly,）并且子视图的大小恰好跟父窗口一样大，父窗口必须用给定的大小去layout子视图 
参数含义：spec 父窗口传递给子视图的大小和模式
padding 父窗口的边距，也就是xml中的android:padding
childDimension 子视图想要绘制的准确大小，但最终不一定绘制此值

当得到了每一个子控件的大小以后，再要计算自己的宽高就简单了。
int wantedHeight = childTop + lineHeight + paddingBottom;

同理，在onLayout中的这一句

<code class="language-java"><span class="k"><span class="kwd">for</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="mi"><span class="lit">0</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildCount</span></span><span class="o"><span class="pun">();</span></span><span class="pln"> </span><span class="n"><span class="pln">i</span></span><span class="pln"> </span><span class="o"><span class="pun"><</span></span><span class="pln"> </span><span class="n"><span class="pln">childCount</span></span><span class="o"><span class="pun">;</span></span><span class="pln"> </span><span class="o"><span class="pun">++</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">    </span><span class="n"><span class="typ">View</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">getChildAt</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">i</span></span><span class="o"><span class="pun">);</span></span><span class="pln">    </span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getVisibility</span></span><span class="o"><span class="pun">()</span></span><span class="pln"> </span><span class="o"><span class="pun">==</span></span><span class="pln"> </span><span class="n"><span class="typ">View</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">GONE</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="k"><span class="kwd">continue</span></span><span class="o"><span class="pun">;</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredWidth</span></span><span class="o"><span class="pun">();</span></span><span class="pln">    </span><span class="kt"><span class="kwd">int</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">getMeasuredHeight</span></span><span class="o"><span class="pun">();</span></span><span class="pln">    </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="typ">Math</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">max</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">    </span><span class="k"><span class="kwd">if</span></span><span class="pln"> </span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingRight</span></span><span class="pln"> </span><span class="o"><span class="pun">></span></span><span class="pln"> </span><span class="n"><span class="pln">myWidth</span></span><span class="o"><span class="pun">)</span></span><span class="pln"> </span><span class="o"><span class="pun">{</span></span><span class="pln">        </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">paddingLeft</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">mVerticalSpacing</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">lineHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">        </span><span class="n"><span class="pln">lineHeight</span></span><span class="pln"> </span><span class="o"><span class="pun">=</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">;</span></span><span class="pln">    </span><span class="o"><span class="pun">}</span></span><span class="pln">    </span><span class="n"><span class="pln">childView</span></span><span class="o"><span class="pun">.</span></span><span class="na"><span class="pln">layout</span></span><span class="o"><span class="pun">(</span></span><span class="n"><span class="pln">childLeft</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="o"><span class="pun">,</span></span><span class="pln"> </span><span class="n"><span class="pln">childTop</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">childHeight</span></span><span class="o"><span class="pun">);</span></span><span class="pln">    </span><span class="n"><span class="pln">childLeft</span></span><span class="pln"> </span><span class="o"><span class="pun">+=</span></span><span class="pln"> </span><span class="n"><span class="pln">childWidth</span></span><span class="pln"> </span><span class="o"><span class="pun">+</span></span><span class="pln"> </span><span class="n"><span class="pln">mHorizontalSpacing</span></span><span class="o"><span class="pun">;</span></span><span class="pln"></span><span class="o"><span class="pun">}</span></span></code>

首先通过循环遍历，控制每个item子控件的显示位置，如果当前行还能放得下一个item，就放到当前行，如果放不下就放到下一行的最左边。
最终，遍历完成，也就相当于把自己的位置显示完成了。

效果截图

OpenSourceLaboratory

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查看评论
11楼 Focus100 前天 14:08发表 [回复]
我简化了不少代码，效果一样，大家可以参考这篇：

http://blog.csdn.net/u013519989/article/details/50834180
10楼 huidawoxiaozi 2016-02-03 15:36发表 [回复]
放在scrollview冲突 ：算出总高度，重新再设置一遍高度也可解决ViewGroup.LayoutParams params = flowlayout.getLayoutParams();
params.height = totalHeight;
flowlayout.setLayoutParams(params);
在界面加载完在这个方法里得到总高度public void onWindowFocusChanged(boolean hasFocus) {
9楼 路路路lbj 2016-01-05 10:39发表 [回复]
我的上下两行之间没有margin，可能是什么原因
8楼 o2jam0916 2015-11-17 19:56发表 [回复]
你好大神，我想问一下，我把这个标签流放大ListView中 就不显示了 是什么原因呢？求解 多谢
7楼 爱的不落叶 2015-10-26 13:55发表 [回复]
重写onMeasure方法最后不能调用父类的onMeasure方法。否则无法wrap_content。
6楼 yantaossg 2015-10-15 15:34发表 [回复]
非常感谢，提供的代码。
我想请问下，有没有办法。让每次新生成的标签背景颜色都不一样！
5楼 yunuoqzone19 2015-10-12 19:19发表 [回复]
解决自适应高度的方法是在onMeasure方法中 计算出高度调用setMeasuredDimension方法重新设置高度即可
4楼 AlexSucre 2015-09-08 11:11发表 [回复]
我想问一下，如果我想设置里面的文字居中显示怎么办？我现在想把这个每一个标签设置的比较大，然后居中显示
3楼 3kqing 2015-07-30 18:20发表 [回复]
这个布局放到ScrollView中不显示怎么办呢？XCFlowLayout如果高度设为wrap_content就不能显示。设为固定值才显示。有什么办法能让他设为wrap_content也显示呢？
Re: hzp901203 2015-08-18 13:54发表 [回复]
回复3kqing：把super.onMeasure(widthMeasureSpec, heightMeasureSpec);删掉就行了，并且将onMeasure里面的MarginLayoutParams lp = (MarginLayoutParams) getLayoutParams(); 改成MarginLayoutParams lp =(MarginLayoutParams) child.getLayoutParams();，不然高度算的不对
Re: 596174 2015-11-06 15:17发表 [回复]
回复hzp901203：谢谢，这才是正解
2楼 又丑又不读书 2015-07-20 10:50发表 [回复]
这个布局放到ScrollView中不显示怎么办呢？XCFlowLayout如果高度设为wrap_content就不能显示。设为固定值才显示。有什么办法能让他设为wrap_content也显示呢？我是刚毕业的学生，项目中用到这个，弄了几天都解决不了。麻烦帮看下呢，谢谢了
Re: 一叶飘舟 2015-07-20 11:14发表 [回复]
回复又丑又不读书：下载这个代码：http://download.csdn.net/download/jdsjlzx/8784571
Re: yunuoqzone19 2015-10-12 20:11发表 [回复]
回复一叶飘舟：你这个还是没有解决自适应高度的问题 你哪个是设置的最大高度 - -。
1楼 又丑又不读书 2015-07-20 10:49发表 [回复]
这个布局放到ScrollView中不显示怎么办呢？XCFlowLayout如果高度设为wrap_content就不能显示。设为固定值才显示。有什么办法能让他设为wrap_content也显示呢？我是刚毕业的学生，项目中用到这个，弄了几天都解决不了。麻烦帮看下呢，谢谢了
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