这里直接用系统Dialog中添加了倒计时的显示，如果用自定义Dialog会更美观；

 private TextView mOffTextView; private Handler mOffHandler; private Timer mOffTime; private Dialog mDialog;//////创建对话框void initDialog(){     mOffTextView = new TextView(this);     mDialog = new AlertDialog.Builder(this)    .setTitle("提示")         .setCancelable(false)         .setView(mOffTextView) ////                  .setPositiveButton("确定", new DialogInterface.OnClickListener() {          public void onClick(DialogInterface dialog, int id) {           mOffTime.cancel();           off();////关闭后的一些操作                   }         })         .setNegativeButton("取消", new DialogInterface.OnClickListener() {             public void onClick(DialogInterface dialog, int id) {              dialog.cancel();              mOffTime.cancel();             }         })         .create();   mDialog.show();   mDialog.setCanceledOnTouchOutside(false);    mOffHandler = new Handler() {     public void handleMessage(Message msg) {      if (msg.what > 0) {        ////动态显示倒计时       mOffTextView.setText("    即将关闭："+msg.what);      } else {      ////倒计时结束自动关闭       if(mDialog!=null){        mDialog.dismiss();       }       off();////关闭后的操作       mOffTime.cancel();      }      super.handleMessage(msg);     }    };          //////倒计时         mOffTime = new Timer(true);      TimerTask tt = new TimerTask() {       int countTime = 10;       public void run() {        if (countTime > 0) {         countTime--;        }        Message msg = new Message();        msg.what = countTime;        mOffHandler.sendMessage(msg);       }      };      mOffTime.schedule(tt, 1000, 1000);     }

效果图

Dialog中显示倒计时,到时自动关闭