两个Service之间相互监视的实现

在实际开发中可能需要用到两个Service相互监视的情况，本示例就是实现此功能以作参考。

服务A：

 public class ServiceA extends Service {
 
     private static final String TAG = ServiceA.class.getSimpleName();
     MyBinder mBinder;
     MyServiceConnection mServiceConnection;
     PendingIntent mPendingIntent;
 
     @Override
     public void onCreate() {
         super.onCreate();
 
         if(mBinder==null)
         {
             mBinder=new MyBinder();
         }
         mServiceConnection=new MyServiceConnection();
     }
 
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
         ServiceA.this.bindService(new Intent(ServiceA.this,ServiceB.class),mServiceConnection, Context.BIND_IMPORTANT);
         mPendingIntent=PendingIntent.getService(this,0,intent,0);
         Notification.Builder builder=new Notification.Builder(this);
         builder.setTicker("守护服务A启动中")
                 .setContentText("我是来守护服务B的")
                 .setContentTitle("守护服务A")
                 .setSmallIcon(R.mipmap.ic_launcher)
                 .setContentIntent(mPendingIntent)
                 .setWhen(System.currentTimeMillis());
         Notification notification=builder.build();
 
         startForeground(startId,notification);
 
         return START_STICKY;
     }
 
     @Override
     public IBinder onBind(Intent intent) {
         return mBinder;
     }
 
     public class MyBinder extends IBridgeInterface.Stub {
 
         @Override
         public String getName() throws RemoteException {
             return "name:"+TAG;
         }
     }
 
     class MyServiceConnection implements ServiceConnection {
 
         @Override
         public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
             String name=null;
             try {
                 name= IBridgeInterface.Stub.asInterface(iBinder).getName();
             } catch (RemoteException e) {
                 e.printStackTrace();
             }
 
             Toast.makeText(ServiceA.this,name+"连接成功",Toast.LENGTH_SHORT).show();
         }
 
         @Override
         public void onServiceDisconnected(ComponentName componentName) {
             Toast.makeText(ServiceA.this,TAG+"断开连接",Toast.LENGTH_SHORT).show();
 
             ServiceA.this.startService(new Intent(ServiceA.this,ServiceB.class));
 
             ServiceA.this.bindService(new Intent(ServiceA.this,ServiceB.class),mServiceConnection, Context.BIND_IMPORTANT);
 
         }
     }
 
 }

服务B：

 public class ServiceB extends Service {
 
     private static final String TAG = ServiceB.class.getSimpleName();
     private PendingIntent mPendingIntent;
     private MyBinder mBinder;
     private MyServiceConnection mServiceConnection;
 
     @Override
     public IBinder onBind(Intent intent) {
         return mBinder;
     }
 
     @Override
     public void onCreate() {
         super.onCreate();
         if (mBinder == null) {
             mBinder = new MyBinder();
         }
 
         mServiceConnection = new MyServiceConnection();
     }
 
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
         this.bindService(new Intent(ServiceB.this, ServiceA.class), mServiceConnection, Context.BIND_IMPORTANT);
         mPendingIntent = PendingIntent.getService(this, 0, intent, 0);
         Notification.Builder builder = new Notification.Builder(this);
 
         builder.setTicker("守护服务B启动中")
                 .setContentText("我是来守护服务A的")
                 .setContentTitle("守护服务B")
                 .setSmallIcon(R.mipmap.ic_launcher)
                 .setContentIntent(mPendingIntent)
                 .setWhen(System.currentTimeMillis());
         Notification notification = builder.build();
         startForeground(startId, notification);
 
         return START_STICKY;
     }
 
     public class MyBinder extends IBridgeInterface.Stub {
 
         @Override
         public String getName() throws RemoteException {
             return "name:"+TAG;
         }
     }
 
     class MyServiceConnection implements ServiceConnection {
 
         @Override
         public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
             String name=null;
             try {
                 name=IBridgeInterface.Stub.asInterface(iBinder).getName();
             } catch (RemoteException e) {
                 e.printStackTrace();
             }
             Toast.makeText(ServiceB.this, name + "连接成功", Toast.LENGTH_SHORT).show();
         }
 
         @Override
         public void onServiceDisconnected(ComponentName componentName) {
             Toast.makeText(ServiceB.this, TAG + "断开连接", Toast.LENGTH_SHORT).show();
 
             ServiceB.this.startService(new Intent(ServiceB.this, ServiceA.class));
             ServiceB.this.bindService(new Intent(ServiceB.this, ServiceA.class), mServiceConnection, Context.BIND_IMPORTANT);
         }
     }
 
 }

IBridgeInterface.aidl

 interface IBridgeInterface {
     String getName();
 }

界面：

 public class MainActivity extends Activity {
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
         startService(new Intent(this, ServiceA.class));
         startService(new Intent(this, ServiceB.class));
     }
 
 }

AndroidManifest.xml

         <service android:name=".services.ServiceA" />
         <service
             android:name=".services.ServiceB"
             android:process=":remote" />

由于涉及到跨进程，onServiceConnected() 方法中使用

IBridgeInterface.Stub.asInterface(iBinder).getName();

而不能直接类型转换

((ServiceA.MyBinder)iBinder).getName();

onStartCommand

onStartCommand() 方法必须返回整型数。整型数是一个值，用于描述系统应该如何在服务终止的情况下继续运行服务。

返回的值必须是以下常量之一：

START_NOT_STICKY

　　如果系统在 onStartCommand() 返回后终止服务，则除非有挂起 Intent 要传递，否则系统不会重建服务。

START_STICKY

　　如果系统在 onStartCommand() 返回后终止服务，则会重建服务并调用 onStartCommand()，但绝对不会重新传递最后一个 Intent。相反，除非有挂起 Intent 要启动服务（在这种情况下，将传递这些 Intent ），否则系统会通过空 Intent 调用 onStartCommand()。这适用于不执行命令、但无限期运行并等待作业的媒体播放器（或类似服务）。

START_REDELIVER_INTENT

　　如果系统在 onStartCommand() 返回后终止服务，则会重建服务，并通过传递给服务的最后一个 Intent 调用 onStartCommand()。任何挂起 Intent 均依次传递。这适用于主动执行应该立即恢复的作业（例如下载文件）的服务。