看到一个老外做的不错的android启动菜单的动画效果，小结下。

1 首先在drawable目录下放一些动画要用的图片。

2 splash.xml:
  <?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:id="@+id/TheSplashLayout"
  android:layout_gravity="center"
  >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/SplashImageView"
android:layout_gravity="center"
>
</ImageView>
3 点启动窗口动画效果后显示的main.xml
<?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"
    >
<TextView 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
</LinearLayout>

3 SplashScreen.java
  这里是欢迎启动类的核心部分
  public class SplashScreen extends Activity {

    /**
     * The thread to process splash screen events
     */
    private Thread mSplashThread;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Splash screen view
    setContentView(R.layout.splash);
   
        // Start animating the image
    final ImageView splashImageView = (ImageView) findViewById(R.id.SplashImageView);
    splashImageView.setBackgroundResource(R.drawable.flag);
    final AnimationDrawable frameAnimation = (AnimationDrawable)splashImageView.getBackground();
    splashImageView.post(new Runnable(){

public void run() {
frameAnimation.start();
}    
    });
       
   
    final SplashScreen sPlashScreen = this;  
   
    // The thread to wait for splash screen events
    mSplashThread =  new Thread(){
    @Override
    public void run(){
    try {
    synchronized(this){
    // Wait given period of time or exit on touch
    wait(5000);
    }
    }
    catch(InterruptedException ex){   
    }

    finish();
   
    // Run next activity
    Intent intent = new Intent();
    intent.setClass(sPlashScreen, MainActivity.class);
    startActivity(intent);
    stop();    
    }
    };
   
    mSplashThread.start();
   
}

@Override
public boolean onCreateOptionsMenu(Menu menu){
super.onCreateOptionsMenu(menu);
return false;
}
 
    /**
     * Processes splash screen touch events
     */
    @Override
    public boolean onTouchEvent(MotionEvent evt)
    {
    if(evt.getAction() == MotionEvent.ACTION_DOWN)
    {
    synchronized(mSplashThread){
    mSplashThread.notifyAll();
    }
    }
    return true;
    }
4 为了更好看，在values 目录下添加样式文件
  styles.xml:
<resources>
<style name="Animations" parent="@android:Animation" />
<style name="Animations.SplashScreen">
        <item name="android:windowEnterAnimation">@anim/appear</item>
        <item name="android:windowExitAnimation">@anim/disappear</item>
    </style>
<style name="Theme.Transparent" parent="android:Theme">
<item name="android:windowIsTranslucent">true</item>
<item name="android:windowBackground">@android:color/transparent</item>
<item name="android:windowContentOverlay">@null</item>
<item name="android:windowNoTitle">true</item>
<item name="android:windowIsFloating">true</item>
<item name="android:backgroundDimEnabled">false</item>
<item name="android:windowAnimationStyle">@style/Animations.SplashScreen</item>
</style>
</resources>
注意下这里<style name="Animations" parent="@android:Animation" />
<style name="Animations.SplashScreen">
        <item name="android:windowEnterAnimation">@anim/appear</item>
        <item name="android:windowExitAnimation">@anim/disappear</item>
    </style>
定义了当进入和退出时的动画效果是什么。具体的再
在anim目录下分别有显示和消失的两个效果的XML具体定义：
appear.xml:
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha
android:interpolator="@android:anim/accelerate_interpolator"
android:fromAlpha="0.0" android:toAlpha="1.0"
android:duration="800"
/>
</set>
disppear.xml:
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha
android:interpolator="@android:anim/decelerate_interpolator"
android:fromAlpha="1.0" android:toAlpha="0.0"
android:duration="800"
/>
</set>
这里其实就是透明度的设置而已：
然后在manifest.xml中，设置好使用的样式：
<activity
android:name="SplashScreen"
android:theme="@style/Theme.Transparent"
>
<intent-filter>
<action android:name="android.intent.action.MAIN"></action>
<category android:name="android.intent.category.LAUNCHER"></category>
</intent-filter>
</activity>
即可。

5 另外要注意的是，设置动画效果这段：
   splashImageView.setBackgroundResource(R.drawable.flag);
    final AnimationDrawable frameAnimation = (AnimationDrawable)splashImageView.getBackground();
    splashImageView.post(new Runnable(){

public void run() {
frameAnimation.start();
}    
    });
由于动画效果的设置不能在oncreate中直接设置，而是要从GUI线程中创建的，因此
使用imageview类的POST方法，当GUI创建时就显示这个动画

详细代码可以从附件下载

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