Android---Service Timer之执行周期任务

我们有时候需要隔一段时间去做一件事，比如检查邮件，检查网络情况等等。本篇文章简单介绍下如何使用Service Timer 去执行周期任务，程序界面上显示一个数字，每隔一秒钟更新 ，每5秒钟显示一个toast。

1.自定义service

public class MyService extends Service {    private static final long INTERVAL = 5 * 1000;    private Handler handler = new Handler();    private Timer mTimer;    @Override    public IBinder onBind(Intent arg0) {        return null;    }    @Override    public void onCreate() {        super.onCreate();        // 如果已经存在，则先取消        if (mTimer != null) {            mTimer.cancel();        } else {            mTimer = new Timer();        }        mTimer.scheduleAtFixedRate(new MyTimerTask(), 0, INTERVAL);    }    private class MyTimerTask extends TimerTask {        @Override        public void run() {            // 新开一个线程执行            handler.post(runnable);        }    }    private Runnable runnable = new Runnable() {        @Override        public void run() {            Toast.makeText(getApplicationContext(), getTime(),                    Toast.LENGTH_SHORT).show();        }    };    private String getTime() {        return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());    }    @Override    public void onDestroy() {        super.onDestroy();        mTimer.cancel();    }}

2.activity_main.xml文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.refreshdemo.MainActivity" >    <TextView        android:id="@+id/tvNum"        android:layout_width="wrap_content"        android:layout_height="wrap_content"/></RelativeLayout>

3.MainActivity.java

public class MainActivity extends Activity {    private TextView tvNum;    private int count = 0; // 计数    private Handler handler = new Handler();    private Intent serviceIntent;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        tvNum = (TextView) findViewById(R.id.tvNum);        tvNum.setText("0");        handler.postDelayed(runnable, 1000);        serviceIntent = new Intent(this, MyService.class);        this.startService(serviceIntent);    }    private Runnable runnable = new Runnable() {        @Override        public void run() {            update();            handler.postDelayed(this, 1000);        }    };    private void update() {        count++;        tvNum.setText(count + "");    }    @Override    protected void onDestroy() {        super.onDestroy();        handler.removeCallbacks(runnable);        this.stopService(serviceIntent);    }}

4.最后在AndroidManifest.xml文件中添加Service

<application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@android:style/Theme.Holo.Light">        <activity            android:name=".MainActivity"            android:label="@string/app_name" >            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>        **<service android:name="com.example.refreshdemo.MyService"></service>**    </application>

运行截图：

源码下载