Android中ViewManager的Demo

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。view必须是LinearLayout中某个子视图对象实例的引用。

ViewManagerDemo.java如下：


package eoe.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 textViews;

boolean isEdited = false;

Context context ;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

textViews = new LinkedList();
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));
}
}
});
}
}
}



android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
android:id="@+id/addView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="增加一个TextView"
/>
android:id="@+id/removeView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="删除一个TextView"
/>

android:id="@+id/liLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation = "vertical">
android:id="@+id/textView_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:text="TextView No.1"/>
android:id="@+id/textView_2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="TextView No.2"/>
android:id="@+id/textView_3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView No.3"/>