实现应用程序在Notification在标题栏提醒

public class Main extends Activity
{
?private NotificationManager notificationManager;
?private Notification notification;
??? @Override
??? public void onCreate(Bundle savedInstanceState)
??? {
??????? super.onCreate(savedInstanceState);
??????? setContentView(R.layout.main);
??????? notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
??????? notification = new Notification(R.drawable.ic_launcher, "", System.currentTimeMillis());

??????? Log.d("11111111111", "Oncreate");??????????
??? }
??
?public boolean onKeyDown(int keyCode, KeyEvent event)
?{

???? if(keyCode == KeyEvent.KEYCODE_BACK )
???? {
???? ?showDialog();//调用退出对话框
????? Log.d("back", "back");
???? }
???? return super.onKeyDown(keyCode, event);
?}

??? /**如果用户按下home键，会调用onStop()。发送一个通知。通过这个通知就可以回到原来的界面，而不会调用onCreate方法*/
??? @Override
?protected void onStop()
?{
??Intent notificationIntent = new Intent(Main.this, Main.class);//这个实际上只是指定启动一个Activity，这里选择本身
??notificationIntent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
??PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT);
??notification.flags = Notification.FLAG_ONGOING_EVENT;//这个表示“正在进行的”，而不是“通知”
??notification.setLatestEventInfo(this, "哇哈哈","哥在运行中...", contentIntent);
??notificationManager.notify(R.drawable.ic_launcher, notification);
??
??Log.d("111111111", "onStop");

??super.onStop();
?}
?
??? /**? 重新获得焦点的时候清理notification*/
??? @Override
?protected void onResume()
?{
??notificationManager.cancelAll();
??super.onResume();
?}

?/**? 创建一个对话框，确认是否退出*/
?private void showDialog()
?{
??new AlertDialog.Builder(this).setTitle("是否退出应用程序？")
??.setPositiveButton("确定", new DialogInterface.OnClickListener(){
???
???@Override
???public void onClick(DialogInterface dialog, int which) {
?????//finish();//如果这里执行的是finish(),则也会调用onStop()
????android.os.Process.killProcess(android.os.Process.myPid());//整个结束掉，这样就不会执行onStop()
???}
??}).setNegativeButton("取消", new DialogInterface.OnClickListener() {
???
???@Override
???public void onClick(DialogInterface dialog, int which) {
????
???}
??}).show();
?}

?
}