[Android]Android布局优化之 ViewStub

转载请标注：转载于http://www.cnblogs.com/Liuyt-61/p/6602926.html 

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>使用ViewStub惰性加载

作用：ViewStub标签同include标签一样可以用来引入一个外部布局，不同的是，ViewStub引入的布局默认不会扩张，既不会占用显示，也不会占用位置，从而在解析layout时节省cpu和内存。

common_text.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="隐藏内容" />

</LinearLayout>

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main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <include layout="@layout/common_title" />

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <TextView
            android:id="@+id/textView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="正文内容"
            android:textSize="16sp" />

        <include layout="@layout/common_progress" />
    </FrameLayout>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="显示隐藏内容" />

    <ViewStub
        android:id="@+id/viewStub"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout="@layout/common_text" />

</LinearLayout>
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MainActivity.java

package com.Liuyt.s03_e22_include;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewStub;
import android.widget.Button;

public class MainActivity extends Activity {

    private Button btn;
    private ViewStub viewStub;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = (Button) findViewById(R.id.button);
        viewStub = (ViewStub) findViewById(R.id.viewStub);
        btn.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                viewStub.inflate();
            }
        });
    }
}