Android-贪吃蛇（三）- Mainactivity

package com.example.administrator.eatingjj;import android.media.MediaPlayer;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.KeyEvent;import android.view.WindowManager;import android.widget.Toast;public class MainActivity extends AppCompatActivity {    MediaPlayer mediaPlayer1;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //设置成无状态栏        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,                WindowManager.LayoutParams.FLAG_FULLSCREEN);        setContentView(R.layout.activity_main);        //播放背景音乐        mediaPlayer1 = null;        mediaPlayer1 = MediaPlayer.create(this, R.raw.snake);        mediaPlayer1.start();        //设置循环播放        mediaPlayer1.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {            @Override            public void onCompletion(MediaPlayer mp) {                mediaPlayer1.start();                mediaPlayer1.setLooping(true);            }        });    }    //实现再按一次退出程序    private long exitTime = 0;    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {        if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN){            if((System.currentTimeMillis()-exitTime) > 2000){                Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();                exitTime = System.currentTimeMillis();            } else {                finish();                System.exit(0);            }            return true;        }        return super.onKeyDown(keyCode, event);    }}