学习如何每隔一段时间定时重复执行任务

学习了定时执行任务功能。并写了个demo学习研究下。

demo地址：http://download.csdn.net/detail/violetjack0808/9474145

参考blog：

Android中定时执行任务的3种实现方法

android service 后台执行定时任务

1. 通过Service和BroadcastReceiver实现

写一个Service执行定时发广播操作

public class AlarmService extends Service {

@Override
public IBinder onBind(Intent intent) {
return null;
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// TODO: 16/3/28 如果执行费时操作，可以新起线程，但是觉得线程太多不好
//        new Thread(new Runnable() {
//            @Override
//            public void run() {
//            }
//        }).start();
Log.e("test", "这是一条测试信息");
AlarmManager manager = (AlarmManager) getSystemService(ALARM_SERVICE);
int minute = 1000;
long triggerAtTime = SystemClock.elapsedRealtime() + minute;
Intent i = new Intent(this, AlarmReceiver.class);
PendingIntent pi = PendingIntent.getBroadcast(this, 0, i, 0);
manager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, triggerAtTime, pi);
return super.onStartCommand(intent, flags, startId);
}
}

写一个BroadcastReceiver接收广播启动Service

public class AlarmReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
Intent i = new Intent(context, AlarmService.class);
context.startService(i);
}
}

最后在Activity中实现循环。

/**
* 这个Alarm的循环只能给Service用
* Activity启动Service，Service发送广播，广播接收器接收广播并启动Service，Service再次发送广播，如此重复
*/
public class AlarmActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_alarm);
Intent i = new Intent(this, AlarmService.class);
startService(i);
}

@Override
protected void onDestroy() {
super.onDestroy();
Intent i = new Intent(this, AlarmService.class);
stopService(i);
}
}

最后，假如需要对UI进行操作，完全可以将BroadcastReceiver写在Activity中，来实现定时的UI操作。

一直启动Service我不觉得是一个好的解决方案，个人不喜欢用。

2. 通过Handler和Runnable实现循环

/**
* 通过handler的post方法使用runnable，在runnable中使用handler的post方法post当前runnable,如此循环。
*/
public class HandlerActivity extends AppCompatActivity {

private TextView tvNumber;
private static int number = 0;

private Handler handler = new Handler();
private Runnable runnable = new Runnable() {
@Override
public void run() {
number++;
tvNumber.setText("" + number);
//延时1秒post
handler.postDelayed(this, 1000);
}
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_handler);
tvNumber = (TextView) findViewById(R.id.tvNum01);
findViewById(R.id.btnStart01).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startHandleLoop();
}
});
findViewById(R.id.btnStop01).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
stopHandleLoop();
}
});

}

/**
* 开始循环
*/
private void startHandleLoop(){
//延时1秒post
handler.postDelayed(runnable, 1000);
}

/**
* 停止循环
*/
private void stopHandleLoop(){
handler.removeCallbacks(runnable);
}
}

3. 通过new一个无限循环的线程，设置sleep实现循环

/**
* 通过新建一个线程，无限循环，并设置sleep时间，实现每隔一秒刷新的功能。
*/
public class SleepActivity extends AppCompatActivity {

private static int number = 0;
private TextView tvNumber;
private Handler handler3 = new Handler(){
@Override
public void handleMessage(Message msg) {
number++;
tvNumber.setText("" + number);
super.handleMessage(msg);
}
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sleep);
tvNumber = (TextView) findViewById(R.id.tvNum02);
findViewById(R.id.btnStart02).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
new Thread(new LoopRnuable()).start();
}
});
}

public class LoopRnuable implements Runnable{

@Override
public void run() {
while (true) {
try {
Thread.sleep(1000);
Message msg = new Message();
msg.what = 1;
handler3.sendMessage(msg);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}

4. 通过Timer实现重复循环

/**
* 通过Timer的schedule方法使用TimerTask，TimerTask的内容是Handler发送消息。
* 为啥用Handler呢，因为UI变化只能在UI线程~~
*/
public class TimerActivity extends AppCompatActivity {

private static int number = 0;
private TextView tvNumber;
private Timer timer;
private TimerTask task = new TimerTask() {
@Override
public void run() {
//TODO 这里可以执行定时非UI操作
Message message = new Message();
message.what = 1;
handler.sendMessage(message);
}
};

/**
* 处理UI操作
*/
private Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
number++;
tvNumber.setText("" + number);
}
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_timer);
tvNumber = (TextView) findViewById(R.id.tvNum03);
timer = new Timer();
findViewById(R.id.btnStart03).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startTimmerLoop();
}
});
findViewById(R.id.btnStop03).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
stopTimerLoop();
}
});
}

/**
* TODO 当timer被stop之后再次start会报错 timer is canceled
*/
private void startTimmerLoop() {
timer.schedule(task, 1000, 1000);//第二个参数是等待一秒后执行schedule，第三个参数是每隔一秒重复执行一次
}

private void stopTimerLoop() {
timer.cancel();
}
}

大多分析都用注释的方式写在代码中了~