Android 应用启动渐变效果

/**
 * 应用程序启动类：显示欢迎界面并跳转到主界面
 * @author liux (http://my.oschina.net/liux)
 * @version 1.0
 * @created 2012-3-21
 */
public class AppStart extends Activity {
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        View view = View.inflate(this, R.layout.start, null);
        setContentView(view);
        
        //渐变展示启动屏
        AlphaAnimation aa = new AlphaAnimation(0.3f,1.0f);
        aa.setDuration(2000);
        view.startAnimation(aa);
        aa.setAnimationListener(new AnimationListener()
        {
            @Override
            public void onAnimationEnd(Animation arg0) {
                redirectTo();
            }
            @Override
            public void onAnimationRepeat(Animation animation) {}
            @Override
            public void onAnimationStart(Animation animation) {}
            
        });
    }
    
    /**
     * 跳转到...
     */
    private void redirectTo(){        
        Intent intent = new Intent(this, Main.class);
        startActivity(intent);
        finish();
    }
}