Android Jamendo开源在线音乐播放器源码分析三 程序首界面

整个程序的入口Activity从Manifest里面可以找到是SplashscreenActivity，界面截图如下：



程序的代码如下：

public class SplashscreenActivity extends Activity {
	public final static String FIRST_RUN_PREFERENCE = "first_run";
	
	private Animation endAnimation;
	
	private Handler endAnimationHandler;
	private Runnable endAnimationRunnable;
	
	/* (non-Javadoc)
	 * @see android.app.Activity#onCreate(android.os.Bundle)
	 */
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.splashscreen);
		findViewById(R.id.splashlayout);

		endAnimation = AnimationUtils.loadAnimation(this, R.anim.fade_out);
		endAnimation.setFillAfter(true);
		
		endAnimationHandler = new Handler();
		endAnimationRunnable = new Runnable() {
			@Override
			public void run() {
				findViewById(R.id.splashlayout).startAnimation(endAnimation);
			}
		};
		
		endAnimation.setAnimationListener(new AnimationListener() {
			@Override
			public void onAnimationStart(Animation animation) {	}
			
			@Override
			public void onAnimationRepeat(Animation animation) { }
			
			@Override
			public void onAnimationEnd(Animation animation) {
				HomeActivity.launch(SplashscreenActivity.this);
				SplashscreenActivity.this.finish();
			}
		});

		showTutorial();
	}
	
	final void showTutorial() {
		boolean showTutorial = PreferenceManager.getDefaultSharedPreferences(this).getBoolean(FIRST_RUN_PREFERENCE, true);
		if (showTutorial) {
			final TutorialDialog dlg = new TutorialDialog(this);
			dlg.setOnDismissListener(new DialogInterface.OnDismissListener() {
				@Override
				public void onDismiss(DialogInterface dialog) {
					CheckBox cb = (CheckBox) dlg.findViewById(R.id.toggleFirstRun);
					if (cb != null && cb.isChecked()) {
						SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(SplashscreenActivity.this);
						prefs.edit().putBoolean(FIRST_RUN_PREFERENCE, false).commit();
					}
					endAnimationHandler.removeCallbacks(endAnimationRunnable);
					endAnimationHandler.postDelayed(endAnimationRunnable, 2000);
				}
			});
			dlg.show();

		} else {
			endAnimationHandler.removeCallbacks(endAnimationRunnable);
			endAnimationHandler.postDelayed(endAnimationRunnable, 1500);
		}
	}
}

备注一：SharedPreferences的保存

SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(SplashscreenActivity.this);

prefs.edit().putBoolean(FIRST_RUN_PREFERENCE, false).commit();

刚开始的时候以为传入的是SplashscreenActivity，那么生成的那个xml文件的名字应该是和这个activity有关才对，手机没有root权限所以通脱调试看到不是这样的



看以看到是和整个程序的包名有关，现在明白其实这个函数的参数只要是传入的是属于这个程序的context的对象就可以。

再有就是对于何时判断实现这个对话框的判断，刚开始想在onCreate()里面判断是不是显示不是更好，后来发现这样做不好，程序的封装行就被破坏了，我要处理是不是显示对话框，onCreate()只要调用一个函数就可以了,不管你在你在里面是怎样处理的是显示还是不显示。

备注二：动画的处理

如果这个动画让我处理的话可能就是执行动画然后，执行完了跳到对应的activity中去。而在这里是用Handler和Runnable来处理的。

endAnimationHandler.removeCallbacks(endAnimationRunnable);

endAnimationHandler.postDelayed(endAnimationRunnable, 1500);

API中的解释：

void android.os.Handler.removeCallbacks(Runnable r)

Remove any pending posts of Runnable r that are in the message queue.


boolean android.os.Handler.postDelayed(Runnable r, long delayMillis)


Causes the Runnable r to be added to the message queue, to be run after the specified amount of time elapses. The runnable will be run on the thread to which this handler is attached.

Parameters:r The Runnable that will be executed.delayMillis The delay (in milliseconds) until the Runnable will be executed.Returns:Returns true if the Runnable was successfully placed in to the message queue. Returns false on failure, usually because the looper processing the message queue is exiting. Note that a result of true does not mean the Runnable will be processed -- if the
looper is quit before the delivery time of the message occurs then the message will be dropped.
启动这个Runnable后在run()方法里面是findViewById(R.id.splashlayout).startAnimation(endAnimation);可以看出是在view上启动某个动画，动画执行一段时间之后要结束的，结束后要跳到相应的Activity中去，这里使用的是给这个动画加了一个监听事件，当onAnimationEnd的时候：
HomeActivity.launch(SplashscreenActivity.this);

SplashscreenActivity.this.finish();

在HomeActivity里面这个launch是一个静态的函数：

/**
	 * Launch Home activity helper
	 * 
	 * @param c context where launch home from (used by SplashscreenActivity)
	 */
	public static void launch(Context c){
		Intent intent = new Intent(c, HomeActivity.class);
		intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP );
		c.startActivity(intent);
	}

intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP );这里先留一个问题，查了一下还是没能太明白这个的准确意思

备注三：对dialog添加消失的监听事件

dlg.setOnDismissListener(new DialogInterface.OnDismissListener() {}

之前一直不知道有这么一个监听事件，以后可以在程序中使用到