Android中的Service使用

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

1. package jtapp.myservicesamples;
2. import android.app.Activity;
3. import android.content.ComponentName;
4. import android.content.Context;
5. import android.content.Intent;
6. import android.content.ServiceConnection;
7. import android.os.Bundle;
8. import android.os.IBinder;
9. import android.util.Log;
10. import android.view.View;
11. import android.view.View.OnClickListener;
12. import android.widget.Button;
13. import android.widget.Toast;
14. public class AcMain extends Activity implements OnClickListener {
15. private static final String TAG = "AcMain";
16. private Button btnStart;
17. private Button btnStop;
18. private Button btnBind;
19. private Button btnExit;
20. /** Called when the activity is first created. */
21. @Override
22. public void onCreate(Bundle savedInstanceState) {
23. super.onCreate(savedInstanceState);
24. setContentView(R.layout.main);
25. findView();
26. }
27. private void findView() {
28. btnStart = (Button) findViewById(R.id.Start);
29. btnStop = (Button) findViewById(R.id.Stop);
30. btnBind = (Button) findViewById(R.id.Bind);
31. btnExit = (Button) findViewById(R.id.Exit);
32. btnStart.setOnClickListener(this);
33. btnStop.setOnClickListener(this);
34. btnBind.setOnClickListener(this);
35. btnExit.setOnClickListener(this);
36. }
37. @Override
38. public void onClick(View v) {
39. Intent intent = new Intent("jtapp.myservicesamples.myservice");
40. switch(v.getId()) {
41. case R.id.Start:
42. startService(intent);
43. Toast.makeText(this,
44. "myservice running " + MyService.msec/1000.0 + "s.",
45. Toast.LENGTH_LONG).show();
46. break;
47. case R.id.Stop:
48. stopService(intent);
49. Toast.makeText(this,
50. "myservice running " + MyService.msec/1000.0 + "s.",
51. Toast.LENGTH_LONG).show();
52. break;
53. case R.id.Bind:
54. bindService(intent, sc, Context.BIND_AUTO_CREATE);
55. break;
56. case R.id.Exit:
57. this.finish();
58. break;
59. }
60. }
61. private MyService serviceBinder;
62. private ServiceConnection sc = new ServiceConnection() {
63. @Override
64. public void onServiceDisconnected(ComponentName name) {
65. Log.d(TAG, "in onServiceDisconnected");
66. serviceBinder = null;
67. }
68. @Override
69. public void onServiceConnected(ComponentName name, IBinder service) {
70. Log.d(TAG, "in onServiceConnected");
71. serviceBinder = ((MyService.MyBinder)service).getService();
72. }
73. };
74. @Override
75. protected void onDestroy() {
76. //this.unbindService(sc);
77. //this.stopService(
78. //                new Intent("jtapp.myservicesamples.myservice"));
79. super.onDestroy();
80. }
81. }

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main.xml

1. <?xml version="1.0" encoding="utf-8"?>
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
3. android:orientation="vertical" android:layout_width="fill_parent"
4. android:layout_height="fill_parent">
5. <TextView android:layout_width="fill_parent"
6. android:layout_height="wrap_content" android:text="@string/hello" />
7. <Button android:text="Start MyService" android:id="@+id/Start"
8. android:layout_width="wrap_content" android:layout_height="wrap_content"/>
9. <Button android:text="Stop MyService" android:id="@+id/Stop"
10. android:layout_width="wrap_content" android:layout_height="wrap_content"/>
11. <Button android:text="Bind MyService" android:id="@+id/Bind"
12. android:layout_width="wrap_content" android:layout_height="wrap_content"/>
13. <Button android:text="Exit AcMain" android:id="@+id/Exit"
14. android:layout_width="wrap_content" android:layout_height="wrap_content"/>
15. </LinearLayout>

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MyService.java

1. package jtapp.myservicesamples;
2. import android.app.Service;
3. import android.content.Intent;
4. import android.os.Binder;
5. import android.os.IBinder;
6. import android.util.Log;
7. public class MyService extends Service {
8. private static final String TAG = "MyService";
9. public static long msec = 0;
10. private boolean bThreadRunning = true;
11. private final IBinder binder = new MyBinder();
12. public class MyBinder extends Binder {
13. MyService getService() {
14. return MyService.this;
15. }
16. }
17. @Override
18. public IBinder onBind(Intent intent) {
19. return binder;
20. }
21. @Override
22. public void onCreate() {
23. new Thread(new Runnable(){
24. @Override
25. public void run() {
26. while (bThreadRunning) {
27. try {
28. Thread.sleep(100);
29. } catch (InterruptedException e) {
30. }
31. Log.i(TAG, "myservice running " + (msec+=100) + "ms.");
32. }
33. }
34. }).start();
35. }
36. @Override
37. public void onDestroy() {
38. bThreadRunning = false;
39. super.onDestroy(); // 可以不用
40. }
41. }

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AnndroidManifest.xml

1. <?xml version="1.0" encoding="utf-8"?>
2. <manifest xmlns:android="http://schemas.android.com/apk/res/android"
3. package="jtapp.myservicesamples" android:versionCode="1"
4. android:versionName="1.0">
5. <application android:icon="@drawable/icon" android:label="@string/app_name"
6. android:debuggable="true">
7. <activity android:name=".AcMain" android:label="@string/app_name">
8. <intent-filter>
9. <action android:name="android.intent.action.MAIN" />
10. <category android:name="android.intent.category.LAUNCHER" />
11. </intent-filter>
12. </activity>
13. <service android:name="MyService">
14. <intent-filter>
15. <action android:name="jtapp.myservicesamples.myservice"></action>
16. </intent-filter>
17. </service>
18. </application>
19. </manifest>

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