service小结（一）

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service

服务的生命周期

onCreate

onStartCommand

onstart

onBind

onUnbind

onDestory

可以有两种方式来开启service

1.startService(intent);

我们可以多次使用startService(intent)开启服务，但是服务只会创建一次，

也就是说如果服务，如果服务没被创建，当我们以startService(intent)开

启服务时，此时系统会帮我们创建我们要开启的服务，也就会走onCreate()方法；

如果已经存在的话，我们以startService(intent)开启服务，系统不会再从新创

建service,所以此时不会走onCreate()方法。同时我们也可以通过stopService(service)的方法来停止一个service，如果此service存在，即未被销毁，此时系统会调用此service的onDeatory()方法，销毁此service

以startService(intent)方式开启服务，当开启者推出后，服务还是可以再后台继续运行的，所以服务非常适合做没有界面的长期的后台操作的事情，比如：播放音乐，上传数据等

2.bindService()

服务只能被绑定一次，也就是说当服务一旦被宿主（activity,recivier等能与service发生绑定关系的组件）a绑定，就不能再被其他宿主绑定，一直到与a解除绑定关系。此服务才能被其他宿主绑定。另外当a通过bindService(intent)绑定服务时，当调用过一次bindService()方法后

，并且绑定成功后，a在调用bindService()方法是不起作用的。

并且宿主和服务端的生命周期是相关联的，如果宿主销毁了（调用了onDestory方法），服务也会跟着销毁（调用了onDestory 方法），但是如果服务挂了，宿主不一定挂，这个容易理解，因为宿主可以通过unBindService()的方法来解除绑定并销毁service,而服务去没有这种能力。当我们已绑定的方式开启了服务，如果宿主销毁了（调用了onDestory方法），而没有显示的调用unBindService()解除绑定，系统会抛异常，所以必须要求显示调用unBindService()方法进行解绑，而且最好是在宿主的onDestodyf方法中调用此方法比较好。而且显示解绑也只能显示解绑一次，多次显示解绑，也会抛异常。

如果服务被创建了，我们还想调用服务的方法，此时我们需要用到bindservice的方法了

测试代码

MainActivity.java

package com.example.servicedemo;import android.app.Service;import android.content.Intent;import android.os.IBinder;import android.util.Log;public class MyService extends Service {private static final String TAG = "MyService";@Overridepublic IBinder onBind(Intent intent) {Log.e(TAG, "onBind(Intent intent)" + System.currentTimeMillis());return null;}@Overridepublic void onCreate() {super.onCreate();Log.e(TAG, "onCreate()" + System.currentTimeMillis());}@Overridepublic void onStart(Intent intent, int startId) {super.onStart(intent, startId);Log.e(TAG, "onStart(Intent intent, int startId)" + System.currentTimeMillis());}@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {Log.e(TAG, "onStartCommand(Intent intent, int flags, int startId)" + System.currentTimeMillis());return super.onStartCommand(intent, flags, startId);}@Overridepublic void onDestroy() {super.onDestroy();Log.e(TAG, "onDestroy()" + System.currentTimeMillis());}@Overridepublic boolean onUnbind(Intent intent) {Log.e(TAG, "onUnbind(Intent intent)" + System.currentTimeMillis());return super.onUnbind(intent);}}

MyService.java

package com.example.servicedemo;import android.os.Bundle;import android.os.IBinder;import android.app.Activity;import android.content.ComponentName;import android.content.Intent;import android.content.ServiceConnection;import android.view.Menu;import android.view.View;public class MainActivity extends Activity {Intent intent ;private ServiceConnection conn;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);intent = new Intent(this, MyService.class);conn =new MyServiceConnection();}public void startservice(View view) {startService(intent);}public void stopservice(View view) {stopService(intent);}public void bindservice(View view) {bindService(intent, conn, BIND_AUTO_CREATE);}public void unbindservice(View view) {unbindService(conn);}    @Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.activity_main, menu);return true;}private class MyServiceConnection implements ServiceConnection{@Overridepublic void onServiceConnected(ComponentName name, IBinder service) {// TODO Auto-generated method stub}@Overridepublic void onServiceDisconnected(ComponentName name) {// TODO Auto-generated method stub}}}

运行程序：

点击startservice按钮

再点击点击startservice按钮

02-07 18:49:55.732: E/MyService(27318): onCreate()1423306195742
02-07 18:49:55.732: E/MyService(27318): onStartCommand(Intent intent, int flags, int startId)1423306195742
02-07 18:49:55.732: E/MyService(27318): onStart(Intent intent, int startId)1423306195742
02-07 18:49:56.242: E/MyService(27318): onStartCommand(Intent intent, int flags, int startId)1423306196246
02-07 18:49:56.242: E/MyService(27318): onStart(Intent intent, int startId)1423306196246
02-07 18:49:56.822: E/MyService(27318): onStartCommand(Intent intent, int flags, int startId)1423306196833
02-07 18:49:56.822: E/MyService(27318): onStart(Intent intent, int startId)1423306196833

点击stopservice按钮

再点击stopservice按钮

无相关log输出

清空log后

点击bindservice按钮

02-07 18:52:36.322: E/MyService(27318): onCreate()1423306356331
02-07 18:52:36.322: E/MyService(27318): onBind(Intent intent)1423306356331

再点击bindservice按钮

无相关log输出

点击unbindservice按钮

再点击unbindservice按钮

抛异常，程序有可能会停止运行

02-07 18:52:36.322: E/MyService(27318): onCreate()1423306356331
02-07 18:52:36.322: E/MyService(27318): onBind(Intent intent)1423306356331
02-07 18:52:48.692: E/MyService(27318): onUnbind(Intent intent)1423306368702
02-07 18:52:48.692: E/MyService(27318): onDestroy()1423306368702
02-07 18:52:49.882: E/AndroidRuntime(27318): FATAL EXCEPTION: main
02-07 18:52:49.882: E/AndroidRuntime(27318): Process: com.example.servicedemo, PID: 27318
02-07 18:52:49.882: E/AndroidRuntime(27318): java.lang.IllegalStateException: Could not execute method of the activity
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.view.View$1.onClick(View.java:3982)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.view.View.performClick(View.java:4597)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.view.View$PerformClick.run(View.java:18750)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.os.Handler.handleCallback(Handler.java:733)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.os.Handler.dispatchMessage(Handler.java:95)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.os.Looper.loop(Looper.java:136)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.app.ActivityThread.main(ActivityThread.java:5061)
02-07 18:52:49.882: E/AndroidRuntime(27318): at java.lang.reflect.Method.invokeNative(Native Method)
02-07 18:52:49.882: E/AndroidRuntime(27318): at java.lang.reflect.Method.invoke(Method.java:515)
02-07 18:52:49.882: E/AndroidRuntime(27318): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
02-07 18:52:49.882: E/AndroidRuntime(27318): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:603)
02-07 18:52:49.882: E/AndroidRuntime(27318): at dalvik.system.NativeStart.main(Native Method)
02-07 18:52:49.882: E/AndroidRuntime(27318): Caused by: java.lang.reflect.InvocationTargetException
02-07 18:52:49.882: E/AndroidRuntime(27318): at java.lang.reflect.Method.invokeNative(Native Method)
02-07 18:52:49.882: E/AndroidRuntime(27318): at java.lang.reflect.Method.invoke(Method.java:515)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.view.View$1.onClick(View.java:3977)
02-07 18:52:49.882: E/AndroidRuntime(27318): ... 11 more
02-07 18:52:49.882: E/AndroidRuntime(27318): Caused by: java.lang.IllegalArgumentException: Service not registered: com.example.servicedemo.MainActivity$MyServiceConnection@426e7e30
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.app.LoadedApk.forgetServiceDispatcher(LoadedApk.java:922)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.app.ContextImpl.unbindService(ContextImpl.java:1611)
02-07 18:52:49.882: E/AndroidRuntime(27318): at android.content.ContextWrapper.unbindService(ContextWrapper.java:529)
02-07 18:52:49.882: E/AndroidRuntime(27318): at com.example.servicedemo.MainActivity.unbindservice(MainActivity.java:38)
02-07 18:52:49.882: E/AndroidRuntime(27318): ... 14 more

清空logcat

点击startservice按钮，bindservice按钮，unbindservice按钮，stopservice按钮

startservice按钮

bindservice按钮

02-07 18:54:19.922: E/MyService(9919): onCreate()1423306459929
02-07 18:54:19.942: E/MyService(9919): onStartCommand(Intent intent, int flags, int startId)1423306459950
02-07 18:54:19.942: E/MyService(9919): onStart(Intent intent, int startId)1423306459950
02-07 18:54:21.492: E/MyService(9919): onBind(Intent intent)1423306461502

unbindservice按钮

stopservice按钮

清空logcat

依次点击startservice按钮，bindservice按钮，stopservice按钮，unbindservice按钮

startservice按钮

bindservice按钮

02-07 18:55:43.152: E/MyService(9919): onCreate()1423306543161
02-07 18:55:43.152: E/MyService(9919): onStartCommand(Intent intent, int flags, int startId)1423306543164
02-07 18:55:43.152: E/MyService(9919): onStart(Intent intent, int startId)1423306543164
02-07 18:55:44.082: E/MyService(9919): onBind(Intent intent)1423306544093

stopservice按钮(注意确实是按下了stopservice按钮的)

unbindservice按钮

清空logcat

依次点击bindservice按钮，startservice按钮，unbindservice按钮，stopservice按钮

bindservice按钮

02-07 18:56:47.942: E/MyService(9919): onCreate()1423306607951
02-07 18:56:47.942: E/MyService(9919): onBind(Intent intent)1423306607951

startservice按钮

02-07 18:56:47.942: E/MyService(9919): onCreate()1423306607951
02-07 18:56:47.942: E/MyService(9919): onBind(Intent intent)1423306607951
02-07 18:56:48.752: E/MyService(9919): onStartCommand(Intent intent, int flags, int startId)1423306608760
02-07 18:56:48.752: E/MyService(9919): onStart(Intent intent, int startId)1423306608760

unbindservice按钮

stopservice按钮

清空logcat

依次点击bindservice按钮，startservice按钮，stopservice按钮，unbindservice按钮

bindservice按钮

02-07 18:57:58.852: E/MyService(9919): onCreate()1423306678864
02-07 18:57:58.862: E/MyService(9919): onBind(Intent intent)1423306678867

startservice按钮

02-07 18:57:58.852: E/MyService(9919): onCreate()1423306678864
02-07 18:57:58.862: E/MyService(9919): onBind(Intent intent)1423306678867
02-07 18:57:59.662: E/MyService(9919): onStartCommand(Intent intent, int flags, int startId)1423306679668
02-07 18:57:59.662: E/MyService(9919): onStart(Intent intent, int startId)1423306679669

stopservice按钮(注意确实是按下了stopservice按钮的)

unbindservice按钮

清空logcat,

点击startservice,然后按后退键退出应用

02-07 18:47:53.652: E/MyService(27318): onCreate()1423306073659
02-07 18:47:53.652: E/MyService(27318): onStartCommand(Intent intent, int flags, int startId)1423306073659
02-07 18:47:53.652: E/MyService(27318): onStart(Intent intent, int startId)1423306073660

清空logcat,

点击bindservice按钮,然后按后退键退出应用（说明service的生命周期受宿主约束）

02-07 18:37:08.872: E/MyService(27318): onCreate()1423305428876
02-07 18:37:08.872: E/MyService(27318): onBind(Intent intent)1423305428876
02-07 18:37:14.692: E/MyService(27318): onUnbind(Intent intent)1423305434699
02-07 18:37:14.692: E/MyService(27318): onDestroy()1423305434699
02-07 18:37:14.692: E/ActivityThread(27318): Activity com.example.servicedemo.MainActivity has leaked ServiceConnection com.example.servicedemo.MainActivity$MyServiceConnection@426b9a58 that was originally bound here
02-07 18:37:14.692: E/ActivityThread(27318): android.app.ServiceConnectionLeaked: Activity com.example.servicedemo.MainActivity has leaked ServiceConnection com.example.servicedemo.MainActivity$MyServiceConnection@426b9a58 that was originally bound here
02-07 18:37:14.692: E/ActivityThread(27318): at android.app.LoadedApk$ServiceDispatcher.<init>(LoadedApk.java:970)
02-07 18:37:14.692: E/ActivityThread(27318): at android.app.LoadedApk.getServiceDispatcher(LoadedApk.java:864)
02-07 18:37:14.692: E/ActivityThread(27318): at android.app.ContextImpl.bindServiceCommon(ContextImpl.java:1577)
02-07 18:37:14.692: E/ActivityThread(27318): at android.app.ContextImpl.bindService(ContextImpl.java:1560)
02-07 18:37:14.692: E/ActivityThread(27318): at android.content.ContextWrapper.bindService(ContextWrapper.java:517)
02-07 18:37:14.692: E/ActivityThread(27318): at com.example.servicedemo.MainActivity.bindservice(MainActivity.java:34)
02-07 18:37:14.692: E/ActivityThread(27318): at java.lang.reflect.Method.invokeNative(Native Method)
02-07 18:37:14.692: E/ActivityThread(27318): at java.lang.reflect.Method.invoke(Method.java:515)
02-07 18:37:14.692: E/ActivityThread(27318): at android.view.View$1.onClick(View.java:3977)
02-07 18:37:14.692: E/ActivityThread(27318): at android.view.View.performClick(View.java:4597)
02-07 18:37:14.692: E/ActivityThread(27318): at android.view.View$PerformClick.run(View.java:18750)
02-07 18:37:14.692: E/ActivityThread(27318): at android.os.Handler.handleCallback(Handler.java:733)
02-07 18:37:14.692: E/ActivityThread(27318): at android.os.Handler.dispatchMessage(Handler.java:95)
02-07 18:37:14.692: E/ActivityThread(27318): at android.os.Looper.loop(Looper.java:136)
02-07 18:37:14.692: E/ActivityThread(27318): at android.app.ActivityThread.main(ActivityThread.java:5061)
02-07 18:37:14.692: E/ActivityThread(27318): at java.lang.reflect.Method.invokeNative(Native Method)
02-07 18:37:14.692: E/ActivityThread(27318): at java.lang.reflect.Method.invoke(Method.java:515)
02-07 18:37:14.692: E/ActivityThread(27318): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
02-07 18:37:14.692: E/ActivityThread(27318): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:603)
02-07 18:37:14.692: E/ActivityThread(27318): at dalvik.system.NativeStart.main(Native Method)

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