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用于確定背景圖
  private boolean flagI = true;//i 用于控制日期顯隱
  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
      //獲取當前時間
      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();//系統狀態欄透明
    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);
  }
  //事件刷新線程
  private void refreshTime(){
    new Thread(){//每秒更新時間
      @Override
      public void run() {
        while (true){
          Message meg = new Message();
          handler.sendMessage(meg);
          try {
            sleep(1000);
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
        }
      }
    }.start();
  }
  //日期顯隱點擊事件
  public void show(View view){
    if(flagI) {
      textViewDate.setVisibility(View.GONE);
      flagI = false;
    }//重新顯現方法在背景按鈕上
  }
  //懸浮按鈕 更換背景
  public void change(View view){
    imageView.setImageResource(imageIds[num++]);
    num %= 4;
    textViewDate.setVisibility(View.VISIBLE);
    flagI = true;
  }
  //設置系統菜單為透明
  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);
    }
  }
}