关系：
IntentService继承service
区别：
IntentService 是一个带有HandlerThread的线程的service，把任务执行完成以后IntentService自动销毁。
Service要手动 调用stopSelf（）来销毁。
IntentService 运行在子线程中，Service运行在主线程中
作用：
IntentService 用于执行一次复杂的场景使用IntentService相对好一点
Service 用于重复执行的场景
代码分析：
IntentService 运行在子线程中，Service运行在主线程中
MyService 继承Service
1 package com.example.activitynate;
2
3 import android.app.Service;
4 import android.content.Intent;
5 import android.os.IBinder;
6
7 public class MyService extends Service {
8
9 @Override
10 public IBinder onBind(Intent intent) {
11 return null;
12 }
13
14 @Override
15 public int onStartCommand(Intent intent, int flags, int startId) {
16 System.out.println("MyService ===== 所在的线程 "+Thread.currentThread());
17 return super.onStartCommand(intent, flags, startId);
18 }
19 }
MyIntentService 继承IntentService
1 package com.example.activitynate;
2
3 import android.app.IntentService;
4 import android.content.Intent;
5
6 public class MyIntentService extends IntentService {
7
8 public MyIntentService(String name) {
9 super(name);
10
11 }
12 public MyIntentService() {
13 this("lihao");
14 }
15
16 @Override
17 protected void onHandleIntent(Intent intent) {
18 System.out.println("MyIntentService ===== 所在的线程 "+Thread.currentThread());
19 }
20
21
22
23 }
运行结果：
04-07 00:41:58.245: I/System.out(5107): MyService ===== 所在的线程 Thread[main,5,main]
04-07 00:41:58.255: I/System.out(5107): MyIntentService ===== 所在的线程 Thread[IntentService[lihao],5,main]
为什么MyIntentService 会在IntentService[lihao]这个线程中
1 public abstract class IntentService extends Service {
2 private volatile Looper mServiceLooper;
3 private volatile ServiceHandler mServiceHandler;
4 private String mName;
5 private boolean mRedelivery;
6
7 private final class ServiceHandler extends Handler {
8 public ServiceHandler(Looper looper) {
9 super(looper);
10 }
11
12 @Override
13 public void handleMessage(Message msg) {
14 onHandleIntent((Intent)msg.obj);
15 stopSelf(msg.arg1);
16 }
17 }
18
19 /**
20 * Creates an IntentService. Invoked by your subclass‘s constructor.
21 *
22 * @param name Used to name the worker thread, important only for debugging.
23 */
24 public IntentService(String name) {
25 super();
26 mName = name;
27 }
28
29
30 public void setIntentRedelivery(boolean enabled) {
31 mRedelivery = enabled;
32 }
33
34 @Override
35 public void onCreate() {
36 // TODO: It would be nice to have an option to hold a partial wakelock
37 // during processing, and to have a static startService(Context, Intent)
38 // method that would launch the service & hand off a wakelock.
39
40 super.onCreate();
41 HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");
42 thread.start();
43
44 mServiceLooper = thread.getLooper();
45 mServiceHandler = new ServiceHandler(mServiceLooper);
46 }
47
48 @Override
49 public void onStart(Intent intent, int startId) {
50 Message msg = mServiceHandler.obtainMessage();
51 msg.arg1 = startId;
52 msg.obj = intent;
53 mServiceHandler.sendMessage(msg);
54 }
55
56
57 @Override
58 public int onStartCommand(Intent intent, int flags, int startId) {
59 onStart(intent, startId);
60 return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;
61 }
62
63 @Override
64 public void onDestroy() {
65 mServiceLooper.quit();
66 }
67
68 /**
69 * Unless you provide binding for your service, you don‘t need to implement this
70 * method, because the default implementation returns null.
71 * @see android.app.Service#onBind
72 */
73 @Override
74 public IBinder onBind(Intent intent) {
75 return null;
76 }
77
78
79 protected abstract void onHandleIntent(Intent intent);
80 }
从源代码的41-45行中 IntentService 中维护了一个HandlerThread 和一个Handler 很容易看到我们继承的IntentService的线程的名字
由于HandlerThread是个子线程start以后生成了loop传给Handler所以Handler运行在子线程里面然后，Handler发送消息，，接收到消息以后
会调用handleMessage（）方法这个方法里面又调用了onHandleIntent（），这个方法执行完成后调用stopSelf() 13-14行代码，Service将自动销毁。