Service的生命周期 (适用于2.1及以上)
1. 被startService的
无论是否有任何活动绑定到该Service,都在后台运行。onCreate(若需要) -> onStart(int id, Bundle args). 多次startService,则onStart调用多次,但不会创建多个Service实例,只需要一次stop。该Service一直后台运行,直到stopService或者自己的stopSelf()或者资源不足由平台结束。
2. 被bindService的
调用bindService绑定,连接建立服务一直运行。未被startService只是BindService,则onCreate()执行,onStart(int,Bundle)不被调用;这种情况下绑定被解除,平台就可以清除该Service(连接销毁后,会导致解除,解除后就会销毁)。
3. 被启动又被绑定
类似startService的生命周期,onCreate onStart都会调用。
4. 停止服务时
stopService时显式onDestroy()。或不再有绑定(没有启动时)时隐式调用。有bind情况下stopService()不起作用。
以下是一个简单的实现例子,某些部分需要配合logcat观察。
AcMain.java
- package jtapp.myservicesamples;
- import android.app.Activity;
- import android.content.ComponentName;
- import android.content.Context;
- import android.content.Intent;
- import android.content.ServiceConnection;
- import android.os.Bundle;
- import android.os.IBinder;
- import android.util.Log;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.Button;
- import android.widget.Toast;
- public class AcMain extends Activity implements OnClickListener {
- private static final String TAG = "AcMain";
- private Button btnStart;
- private Button btnStop;
- private Button btnBind;
- private Button btnExit;
-
- /** Called when the activity is first created. */
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
-
- findView();
- }
-
- private void findView() {
- btnStart = (Button) findViewById(R.id.Start);
- btnStop = (Button) findViewById(R.id.Stop);
- btnBind = (Button) findViewById(R.id.Bind);
- btnExit = (Button) findViewById(R.id.Exit);
-
- btnStart.setOnClickListener(this);
- btnStop.setOnClickListener(this);
- btnBind.setOnClickListener(this);
- btnExit.setOnClickListener(this);
- }
-
- @Override
- public void onClick(View v) {
- Intent intent = new Intent("jtapp.myservicesamples.myservice");
- switch(v.getId()) {
- case R.id.Start:
- startService(intent);
- Toast.makeText(this,
- "myservice running " + MyService.msec/1000.0 + "s.",
- Toast.LENGTH_LONG).show();
- break;
- case R.id.Stop:
- stopService(intent);
- Toast.makeText(this,
- "myservice running " + MyService.msec/1000.0 + "s.",
- Toast.LENGTH_LONG).show();
- break;
- case R.id.Bind:
- bindService(intent, sc, Context.BIND_AUTO_CREATE);
- break;
- case R.id.Exit:
- this.finish();
- break;
- }
- }
-
- private MyService serviceBinder;
-
- private ServiceConnection sc = new ServiceConnection() {
- @Override
- public void onServiceDisconnected(ComponentName name) {
- Log.d(TAG, "in onServiceDisconnected");
- serviceBinder = null;
- }
- @Override
- public void onServiceConnected(ComponentName name, IBinder service) {
- Log.d(TAG, "in onServiceConnected");
- serviceBinder = ((MyService.MyBinder)service).getService();
- }
- };
-
- @Override
- protected void onDestroy() {
- //this.unbindService(sc);
- //this.stopService(
- // new Intent("jtapp.myservicesamples.myservice"));
- super.onDestroy();
- }
- }
main.xml
- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- android:orientation="vertical" android:layout_width="fill_parent"
- android:layout_height="fill_parent">
- <TextView android:layout_width="fill_parent"
- android:layout_height="wrap_content" android:text="@string/hello" />
- <Button android:text="Start MyService" android:id="@+id/Start"
- android:layout_width="wrap_content" android:layout_height="wrap_content"/>
- <Button android:text="Stop MyService" android:id="@+id/Stop"
- android:layout_width="wrap_content" android:layout_height="wrap_content"/>
- <Button android:text="Bind MyService" android:id="@+id/Bind"
- android:layout_width="wrap_content" android:layout_height="wrap_content"/>
- <Button android:text="Exit AcMain" android:id="@+id/Exit"
- android:layout_width="wrap_content" android:layout_height="wrap_content"/>
- </LinearLayout>
MyService.java
- package jtapp.myservicesamples;
- import android.app.Service;
- import android.content.Intent;
- import android.os.Binder;
- import android.os.IBinder;
- import android.util.Log;
- public class MyService extends Service {
- private static final String TAG = "MyService";
- public static long msec = 0;
- private boolean bThreadRunning = true;
-
-
- private final IBinder binder = new MyBinder();
- public class MyBinder extends Binder {
- MyService getService() {
- return MyService.this;
- }
- }
- @Override
- public IBinder onBind(Intent intent) {
- return binder;
- }
-
- @Override
- public void onCreate() {
- new Thread(new Runnable(){
- @Override
- public void run() {
- while (bThreadRunning) {
- try {
- Thread.sleep(100);
- } catch (InterruptedException e) {
- }
- Log.i(TAG, "myservice running " + (msec+=100) + "ms.");
- }
- }
- }).start();
- }
-
- @Override
- public void onDestroy() {
- bThreadRunning = false;
- super.onDestroy(); // 可以不用
- }
-
- }
复制代码
AnndroidManifest.xml
- <?xml version="1.0" encoding="utf-8"?>
- <manifest xmlns:android="http://schemas.android.com/apk/res/android"
- package="jtapp.myservicesamples" android:versionCode="1"
- android:versionName="1.0">
- <application android:icon="@drawable/icon" android:label="@string/app_name"
- android:debuggable="true">
- <activity android:name=".AcMain" 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="MyService">
- <intent-filter>
- <action android:name="jtapp.myservicesamples.myservice"></action>
- </intent-filter>
- </service>
- </application>
- </manifest>