mainActivity部分：

public class MainActivity extends AppCompatActivity {  private int[] imageIds = new int[]{      R.drawable.bac_1,      R.drawable.bac_2,      R.drawable.bac_3,      R.drawable.bac_4  };  private int num = 1;     //num用于确定背景图  private boolean flagI = true;//i 用于控制日期显隐  private ImageView imageView;  private TextView textView;  private TextView textViewDate;  private Handler handler = new Handler(){    @Override    public void handleMessage(Message msg) {      SimpleDateFormat simpleDateFormat = new SimpleDateFormat("HH:mm:ss");// HH:mm:ss      //获取当前时间      Date date = new Date(System.currentTimeMillis());      textView.setText("" + simpleDateFormat.format(date));      simpleDateFormat = new SimpleDateFormat("yyyy年MM月dd日");// HH:mm:ss      textViewDate.setText("" + simpleDateFormat.format(date));    }  };  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);    transparency();//系统状态栏透明    textView = (TextView) findViewById(R.id.txt);    imageView = (ImageView) findViewById(R.id.background);    textViewDate = (TextView) findViewById(R.id.date);    refreshTime();    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);  }  //事件刷新线程  private void refreshTime(){    new Thread(){//每秒更新时间      @Override      public void run() {        while (true){          Message meg = new Message();          handler.sendMessage(meg);          try {            sleep(1000);          } catch (InterruptedException e) {            e.printStackTrace();          }        }      }    }.start();  }  //日期显隐点击事件  public void show(View view){    if(flagI) {      textViewDate.setVisibility(View.GONE);      flagI = false;    }//重新显现方法在背景按钮上  }  //悬浮按钮 更换背景  public void change(View view){    imageView.setImageResource(imageIds[num++]);    num %= 4;    textViewDate.setVisibility(View.VISIBLE);    flagI = true;  }  //设置系统菜单为透明  private void transparency(){    if (Build.VERSION.SDK_INT >= 21) {      View decorView = getWindow().getDecorView();      decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);      getWindow().setStatusBarColor(Color.TRANSPARENT);    }  }}