ViewManager的Demo

LinearLayout实现了ViewManager接口。

当LinearLayout调用addView (View view, 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 (View view)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 (View view, 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addView
					if(!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View
					if(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"
    >
    <LinearLayout
		android: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>
	<LinearLayout
		android:id="@+id/liLayout"
		android:layout_width="fill_parent"
		android:layout_height="fill_parent"
		android:orientation = "vertical">
		<TextView
			android:id="@+id/textView_1"
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:gravity="center"
			android:text="TextView No.1"/>
		<TextView
			android:id="@+id/textView_2"
			android:layout_width="fill_parent"
			android:layout_height="wrap_content"
			android:gravity="center"
			android:text="TextView No.2"/>
		<TextView
			android: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：