Android中一个动态更新时间并显示的小例子

这是一个利用线程和Handler配合更新时间的小例子：

1.主Activity：

public class TestTimeChangedActivity extends Activity{
	private TextView tvTime ;
	private TimeReceiver receiver ;
	Handler mHandler ;
	private static final int FLUSH_TIME_STATE = 100;
	private boolean timeFlush = true ;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.time_layout) ;
		
		tvTime = (TextView) this.findViewById(R.id.tv_times) ;
		
		register() ;
		setHandler();
		new TimeThread().start() ;
	}

	//控制时间更新的线程
	private class TimeThread extends Thread{

		@Override
		public void run() {
			super.run();
			while (timeFlush) {
				mHandler.sendEmptyMessage(FLUSH_TIME_STATE) ;
			}
		}
	}
	//实际更新时间的Handler
	private void setHandler() {
		mHandler = new Handler(){
			public void handleMessage(android.os.Message msg) {
				switch (msg.what) {
				case FLUSH_TIME_STATE:
					updateTime() ;
					break;

				default:
					break;
				}
			};
		} ;
	}
	
	
	//注册时间变化的广播
	private void register() {
		IntentFilter filter = new IntentFilter() ;
		filter.addAction(Intent.ACTION_TIME_CHANGED) ;
		filter.addAction(Intent.ACTION_TIMEZONE_CHANGED) ;
		receiver = new TimeReceiver() ;
		this.registerReceiver(receiver, filter) ;
	}
	
	//时间变化之后更新时间
	private class TimeReceiver extends BroadcastReceiver {

		@Override
		public void onReceive(Context context, Intent intent) {
			updateTime() ;
		}


		
	}
	//更新时间的函数
	private void updateTime() {
		SimpleDateFormat timeFormat = null;
		boolean is24 = DateFormat.is24HourFormat(this);
		if (!is24) {
			timeFormat = new SimpleDateFormat("hh:mm a");
		} else {
			timeFormat = new SimpleDateFormat("HH:mm");
		}
		Date now = Calendar.getInstance().getTime();
		tvTime.setText(timeFormat.format(now));

	}
	
	@Override
	protected void onDestroy() {
		super.onDestroy();
		if (receiver != null) {
			this.unregisterReceiver(receiver) ;
		}
	}
}

2.xml文件：time_layout

<?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:id="@+id/tv_times"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
 />

</LinearLayout>