自定义ViewGroup 五彩缤纷的流式布局,并且自动填充满整个屏幕

在此文章中将有以下知识点：
1 自定义ViewGroup omeasure()onLayout()的使用；
2 使用代码动态的创建状态选择器
3 随机生成的textview的颜色
3 使用代码创建shape图片

效果如图 就是父View测量子view的宽高后 如果子View已经到达了父View的宽度或者 在父view已经填充了几个子view后剩余的宽度不足以在填充后来再加进来的子view就自动换行 依此类推！
当子view填充后 如果父view还有剩余空间的话 让已经填充的子view平均来分配还剩余的空间，如果当前只有一个子view的话 则填充整个父宽度；

好了 开始帖代码：

自定义viewgroup
FlowLayout.java

package com.example.administrator.myapplication.layout;import android.content.Context;import android.util.AttributeSet;import android.view.View;import android.view.ViewGroup;import com.example.administrator.myapplication.MainActivity;import java.util.ArrayList;import java.util.List;public class FlowLayout extends ViewGroup {    private int horizontolSpacing;    private int verticalSpacing;    public FlowLayout(Context context) {        super(context);        init(context);    }    public FlowLayout(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        init(context);    }    private Line currentline;// 当前的行    private int useWidth = 0;// 当前行使用的宽度    private List<Line> mLines = new ArrayList<FlowLayout.Line>();    private int width;    public FlowLayout(Context context, AttributeSet attrs) {        super(context, attrs);        init(context);    }    private void init(Context context) {        horizontolSpacing = MainActivity.dip2px(13, context);        verticalSpacing = MainActivity.dip2px(13, context);    }    // 测量 当前控件Flowlayout    // 父类是有义务测量每个子View的    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        mLines.clear();        currentline = null;        useWidth = 0;        /**         * 获得此ViewGroup上级容器为其推荐的宽和高，以及计算模式         */        int widthMode = MeasureSpec.getMode(widthMeasureSpec);        int heightMode = MeasureSpec.getMode(heightMeasureSpec);        // 计算出所有的childView的宽和高        measureChildren(widthMeasureSpec, heightMeasureSpec);        width = MeasureSpec.getSize(widthMeasureSpec) - getPaddingLeft() - getPaddingRight();        int height = MeasureSpec.getSize(heightMeasureSpec) - getPaddingBottom() - getPaddingTop(); // 获取到宽和高        int childeWidthMode;        int childeHeightMode;        //  为了测量每个子View 需要指定每个子View测量规则        childeWidthMode = widthMode == MeasureSpec.EXACTLY ? MeasureSpec.AT_MOST : widthMode;        childeHeightMode = heightMode == MeasureSpec.EXACTLY ? MeasureSpec.AT_MOST : heightMode;        int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(childeWidthMode, width);        int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(childeHeightMode, height);        currentline = new Line();// 创建了第一行        for (int i = 0; i < getChildCount(); i++) {            View child = getChildAt(i);            // 测量每个子View            child.measure(childWidthMeasureSpec, childHeightMeasureSpec);            int measuredWidth = child.getMeasuredWidth();            useWidth += measuredWidth;// 让当前行加上使用的长度            if (useWidth <= width) {                currentline.addChild(child);//这时候证明当前的子View是可以放进当前的行里,放进去                useWidth += horizontolSpacing;            } else {                //换行                newLine(child);            }        }        if (!mLines.contains(currentline)) {            mLines.add(currentline);// 添加最后一行        }        int totalheight = 0;        for (Line line : mLines) {            totalheight += line.getHeight();        }        totalheight += verticalSpacing * (mLines.size() - 1) + getPaddingTop() + getPaddingBottom();        System.out.println(totalheight);        setMeasuredDimension(width + getPaddingLeft() + getPaddingRight(), resolveSize(totalheight, heightMeasureSpec));    }    private void newLine(View child) {        mLines.add(currentline);// 记录之前的行        currentline = new Line();// 创建新的一行        currentline.addChild(child);        useWidth = currentline.lineWidth;    }    private class Line {        int height = 0; //当前行的高度        int lineWidth = 0;        private List<View> children = new ArrayList<View>();        /**         * 添加一个子View         *         * @param child         */        public void addChild(View child) {            children.add(child);            if (child.getMeasuredHeight() > height) {                height = child.getMeasuredHeight();            }            lineWidth += child.getMeasuredWidth();        }        public int getHeight() {            return height;        }        /**         * 返回子View的数量         *         * @return         */        public int getChildCount() {            return children.size();        }        public void layout(int l, int t) {            lineWidth += horizontolSpacing * (children.size() - 1);            int surplusChild = 0;            int surplus = width - lineWidth;            if (surplus > 0 && children.size() > 0) {                surplusChild = surplus / children.size();            }            for (int i = 0; i < children.size(); i++) {                View child = children.get(i);                child.layout(l, t, l + child.getMeasuredWidth() + surplusChild, t + child.getMeasuredHeight());                l += child.getMeasuredWidth() + surplusChild;                l += horizontolSpacing;            }        }    }    // 分配每个子View的位置    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        l += getPaddingLeft();        t += getPaddingTop();        for (int i = 0; i < mLines.size(); i++) {            Line line = mLines.get(i);            line.layout(l, t);  //交给每一行去分配            t += line.getHeight() + verticalSpacing;        }    }}

MainActivity.java

package com.example.administrator.myapplication;import android.content.Context;import android.graphics.Color;import android.graphics.drawable.Drawable;import android.graphics.drawable.GradientDrawable;import android.graphics.drawable.StateListDrawable;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.Gravity;import android.view.View;import android.widget.LinearLayout;import android.widget.ScrollView;import android.widget.TextView;import android.widget.Toast;import com.example.administrator.myapplication.layout.FlowLayout;import java.util.Random;public class MainActivity extends AppCompatActivity {    private FlowLayout flowLayout;  private String[] data={"编程语言","让当前行加上使用的长度","孩子的数量:11","12","控件实际的大小","BroadcastQueueInjector","currentline.addChild(child)","笔记本","设置4个角的弧度","范围 0-255","博客资讯","600万技术文章","创建状态选择器","按下显示的图片","默认显示的图片","textView可以被点击"};    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        ScrollView root = (ScrollView) findViewById(R.id.root);        flowLayout = new FlowLayout(this);        int padding=dip2px(13,this);        flowLayout.setPadding(padding, padding, padding, padding);        int backColor = 0xffcecece;        Drawable pressedDrawable = createShape(backColor);// 按下显示的图片        for (int i = 0; i < data.length; i++) {            TextView textView = new TextView(this);            textView.setGravity(Gravity.CENTER_HORIZONTAL);            final String str = data[i];            textView.setText(str);            Random random = new Random();   //创建随机            int red = random.nextInt(200) + 22;            int green = random.nextInt(200) + 22;            int blue = random.nextInt(200) + 22;            int color = Color.rgb(red, green, blue);//范围 0-255            GradientDrawable createShape = createShape(color); // 默认显示的图片            StateListDrawable createSelectorDrawable = createSelectorDrawable(pressedDrawable, createShape);// 创建状态选择器            textView.setBackgroundDrawable(createSelectorDrawable);            textView.setTextColor(Color.WHITE);            //textView.setTextSize(UiUtils.dip2px(14));            int textPaddingV = dip2px(4, this);            int textPaddingH = dip2px(7, this);            textView.setPadding(textPaddingH, textPaddingV, textPaddingH, textPaddingV); //设置padding            textView.setClickable(true);//设置textView可以被点击            textView.setOnClickListener(new View.OnClickListener() {  // 设置点击事件                @Override                public void onClick(View v) {                    Toast.makeText(MainActivity.this, str, Toast.LENGTH_SHORT).show();                }            });            flowLayout.addView(textView,new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, -2));// -2 包裹内容        }        root.addView(flowLayout);    }    public GradientDrawable createShape(int color) {        GradientDrawable drawable = new GradientDrawable();        drawable.setCornerRadius(dip2px(5, this));//设置4个角的弧度        drawable.setColor(color);// 设置颜色        return drawable;    }    public StateListDrawable createSelectorDrawable(Drawable pressedDrawable, Drawable normalDrawable) {        StateListDrawable stateListDrawable = new StateListDrawable();        stateListDrawable.addState(new int[]{android.R.attr.state_pressed}, pressedDrawable);// 按下显示的图片        stateListDrawable.addState(new int[]{}, normalDrawable);// 抬起显示的图片        return stateListDrawable;    }    /**     * dip转换px     */    public static int dip2px(int dip, Context context) {        final float scale = context.getResources().getDisplayMetrics().density;        return (int) (dip * scale + 0.5f);    }    /**     * px转换dip     */    public static int px2dip(int px, Context context) {        final float scale = context.getResources().getDisplayMetrics().density;        return (int) (px / scale + 0.5f);    }}

布局文件相对简单 就一个根布局

<?xml version="1.0" encoding="utf-8"?><ScrollView    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:id="@+id/root"    android:layout_height="match_parent"    tools:context="com.example.administrator.myapplication.MainActivity"></ScrollView>