Android 实现定时器的三种方法

本文介绍 Android 实现定时器的三种方法，分别是：方法一 Handler + Thread，方法二 Handler 自带的 postDelyed 方法，方法三 Handler + Timer + TimerTask。

方法一：Handler + Thread

package com.example.qidong;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
public class HanderDemoActivity extends Activity {
  TextView tvShow;
  private int i = 0;
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tvShow = (TextView) findViewById(R.id.tv_show);
    new Thread(new ThreadShow()).start();
  }
  // handler 类接收数据更新 UI
  Handler handler = new Handler() {
    public void handleMessage(Message msg) {
      if (msg.what == 1) {
        tvShow.setText(Integer.toString(i++));
        System.out.println("receive....");
      }
    };
  };
  // 线程类发送消息给主线程
  class ThreadShow implements Runnable {
    @Override
    public void run() {
      // TODO Auto-generated method stub
      while (true) {
        try {
          Thread.sleep(1000);
          Message msg = new Message();
          msg.what = 1;
          handler.sendMessage(msg);
          System.out.println("send...");
        } catch (Exception e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
          System.out.println("thread error...");
        }
      }
    }
  }
}

方法二：Handler 自带的 postDelyed 方法

package com.example.timer;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;
public class HanderDemoActivity extends Activity {
  TextView tvShow;
  private int i = 0;
  private int TIME = 1000; // 每隔1s执行
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tvShow = (TextView) findViewById(R.id.tv_show);
    handler.postDelayed(runnable, TIME); // 开启定时器更新 UI
  }
  Handler handler = new Handler();
  Runnable runnable = new Runnable() {
    @Override
    public void run() {
      // handler 自带方法实现定时器
      try {
        handler.postDelayed(this, TIME);
        tvShow.setText(Integer.toString(i++));
        System.out.println("do...");
      } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("exception...");
      }
    }
  };
}

方法三：Handler + Timer + TimerTask

package com.example.timer;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
public class HanderDemoActivity extends Activity {
  TextView tvShow;
  private int i = 0;
  private int TIME = 1000;
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tvShow = (TextView) findViewById(R.id.tv_show);
    timer.schedule(task, 1000, 1000); // 1s后执行task,经过1s再次执行
  }
  Handler handler = new Handler() {
    public void handleMessage(Message msg) {
      if (msg.what == 1) {
        tvShow.setText(Integer.toString(i++));
      }
      super.handleMessage(msg);
    };
  };
  Timer timer = new Timer();
  TimerTask task = new TimerTask() {
    @Override
    public void run() {
      // 定时任务发送消息
      Message message = new Message();
      message.what = 1;
      handler.sendMessage(message);
    }
  };
}

（完）