ViewManager的Demo

LinearLayout实现了ViewManager接口。

 

当LinearLayout调用addView (Viewview, ViewGroup.LayoutParams params)方法后，LinearLayout中会增加一个子视图，并重新绘制自己。子视图的布局参数是在addView()方法中指定的params。

 

LinearLayout调用removeView (Viewview)方法后，LinearLayout会移除view所引用的实例，并重新绘制自己。view必须是LinearLayout中某个子视图对象实例的引用。

LinearLayout调用UpdateViewLayout (Viewview, ViewGroup.LayoutParams params)，会使得view所引用的实例使用params重新绘制自己。iew必须是LinearLayout中某个子视图对象实例的引用。

 

ViewManagerDemo.java如下：

package com.cnAndroid.api;import java.util.LinkedList;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.view.Gravity;import android.view.View;import android.view.ViewGroup;import android.view.ViewGroup.LayoutParams;import android.widget.Button;import android.widget.LinearLayout;import android.widget.TextView;public class ViewManagerDemo extends Activity { /** Called when the activity is first created. */Button addViewButton;Button removeViewButton;LinearLayout myLayout;private LinkedList<TextView> textViews; boolean isEdited = false;Context context ; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); textViews = new LinkedList<TextView>(); findViews(); setListeners(); context = this; } private void findViews(){ addViewButton = (Button)this.findViewById(R.id.addView); removeViewButton = (Button)this.findViewById(R.id.removeView); myLayout = (LinearLayout)this.findViewById(R.id.liLayout); textViews.addFirst((TextView)this.findViewById(R.id.textView_1)); textViews.addFirst((TextView)this.findViewById(R.id.textView_2)); textViews.addFirst((TextView)this.findViewById(R.id.textView_3)); } private void setListeners(){ if(addViewButton != null){ this.addViewButton.setOnClickListener(new View.OnClickListener() {public void onClick(View v) {TextView myTextView = new TextView(context);myTextView.setText("I am new TextView.");myTextView.setGravity(Gravity.CENTER);textViews.addFirst(myTextView);myLayout.addView(myTextView, new ViewGroup.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));//调用addViewif(!isEdited){isEdited = true;myLayout.updateViewLayout(textViews.getLast(),new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));}}}); } if(removeViewButton != null){ this.removeViewButton.setOnClickListener(new View.OnClickListener() {public void onClick(View v) {TextView tView = textViews.remove();myLayout.removeView(tView);//移除Viewif(isEdited){isEdited = false;myLayout.updateViewLayout(textViews.getLast(),new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));}}}); } }} 

 

main.xml如下：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <LinearLayoutandroid:layout_width="fill_parent"android:layout_height="wrap_content"android:orientation="horizontal"> <Button android:id="@+id/addView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="增加一个TextView" /> <Button android:id="@+id/removeView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="删除一个TextView" /> </LinearLayout><LinearLayoutandroid:id="@+id/liLayout"android:layout_width="fill_parent"android:layout_height="fill_parent"android:orientation = "vertical"><TextViewandroid:id="@+id/textView_1"android:layout_width="wrap_content"android:layout_height="wrap_content"android:gravity="center"android:text="TextView No.1"/><TextViewandroid:id="@+id/textView_2"android:layout_width="fill_parent"android:layout_height="wrap_content"android:gravity="center"android:text="TextView No.2"/><TextViewandroid:id="@+id/textView_3"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="TextView No.3"/></LinearLayout></LinearLayout> 

 

效果图如下：