Android 定时器简单使用及学习

本文，介绍常用定时器实现方式：

1）Handler+Sleep方式

2）Handler+PostDelayed方式

3）Handler+Timer方式

Handler的主要作用就是用来处理接收到的信息，用Handler消息传递机制是为了多个线程 并发 更新U的同时，保证线程安全

1）Handler+Sleep方式

1.1）Handler+Sleep定义

public class HandlerAndSleep {

    public HandlerAndSleep()
    {
    }

    //定义Handler对象，用于处理接收Message
    Handler handler = new Handler(Looper.getMainLooper()){

        @Override
        public void handleMessage(@NonNull Message msg){
            super.handleMessage(msg);
            Log.d("HandlerAndSleep","HandlerAndSleep，时间："+  ToolHelper.GetNowDate());
        }
    };
    //新建一个实现Runnable接口的线程类
    class MyThread implements Runnable{
        @Override
        public void run() {
            while (true){
                try {
                    Thread.sleep(1000);
                    Message message = new Message();
                    message.what = 1;
                    handler.sendMessage(message);

                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    //开启
    public void Start(){
        new Thread(new MyThread()).start();
    }
    //关闭（存在问题，无法使用）
    public void Stop(){
        new Thread(new MyThread()).stop();
    }
}

1.2）Handler+Sleep调用

public class TestActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);

        //HandlerAndSleep实现定时器调用
        HandlerAndSleep handlerAndSleep = new HandlerAndSleep();
        handlerAndSleep.Start();
   }
}

1.3）Handler+Sleep结果

 2）Handler+PostDelayed方式

2.1）Handler+PostDelayed定义

public class HandlerAndPostDelayed {

    public HandlerAndPostDelayed(){

    }

    //定义Handler对象，用于处理接收Message
    Handler handler = new Handler(){

       @Override
        public boolean sendMessageAtTime(@NonNull Message msg,long uptimeMillis){

           Log.d("HandlerAndPostDelayed","HandlerAndPostDelayed，时间："+  ToolHelper.GetNowDate());
           return super.sendMessageAtTime(msg,uptimeMillis);
       }
    };

    Runnable runnable = new Runnable() {
        @Override
        public void run() {

            handler.postDelayed(this,1000);
        }
    };

    //开启定时器
    public void Start(){
        handler.postDelayed(runnable,1000);
    }
    //关闭定时器
    public void Stop(){
        handler.removeCallbacks(runnable);
    }
}

2.2）Handler+PostDelayed调用

public class TestActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);

        //HandlerAndPostDelayed实现定时器调用
        HandlerAndPostDelayed handlerAndPostDelayed = new HandlerAndPostDelayed();
        handlerAndPostDelayed.Start();
   }
}

2.3）Handler+PostDelayed结果

 3）Handler+Timer方式

 3.1）Handler+Timer定义

public class HandlerAndTimer {
    public HandlerAndTimer(){
    }

    private final Timer timer = new Timer();

    Handler handler = new Handler(){
        @Override
        public void handleMessage(@NonNull Message msg){
            Log.d("HandlerAndTimer","HandlerAndTimer，时间："+  ToolHelper.GetNowDate());
            super.handleMessage(msg);
        }
    };

    TimerTask timerTask = new TimerTask() {
        @Override
        public void run() {
            Message message = new Message();
            message.what = 1;
            handler.sendMessage(message);
        }
    };

   public void Start(){
       timer.schedule(timerTask,0,1000);
   }
   public void Stop(){
       timer.cancel();
   }
}

 3.2）Handler+Timer调用

public class TestActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);

       //HandlerAndTimer实现定时器调用
        HandlerAndTimer handlerAndTimer = new HandlerAndTimer();
        handlerAndTimer.Start();
   }
}

3.3）Handler+Timer结果

 附加下获取当前时间方法

public class ToolHelper {

    public static String GetNowDate(){
        //获取当前时间
        Date date = new Date(System.currentTimeMillis());
        //日期格式
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return dateFormat.format(date);
    }
}

参考来源：https://blog.csdn.net/Twan1234/article/details/125050488