ViewManager的Demo

LinearLayout實現了ViewManager接口。

當LinearLayout調用addView (View view, ViewGroup.LayoutParams params)方法後，LinearLayout中會增加一個子視圖，並重新繪制自己。子視圖的布局參數是在addView()方法中指定的params。

LinearLayout調用removeView (View view)方法後，LinearLayout會移除view所引用的實例，並重新繪制自己。view必須是LinearLayout中某個子視圖對象實例的引用。

LinearLayout調用UpdateViewLayout (View view, ViewGroup.LayoutParams params)，會使得view所引用的實例使用params重新繪制自己。iew必須是LinearLayout中某個子視圖對象實例的引用。

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));   //調用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="增加一個TextView" 
        /> 
        <Button 
            android:id="@+id/removeView" 
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content" 
            android:text="刪除一個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> 

效果圖如下：