public class LocalService extends Service {
@Override
public IBinder onBind(Intent intent) {
return new LocalBinder();
}
public void sayHelloWorld(){
Toast.makeText(this.getApplicationContext(), "Hello World Local Service!", Toast.LENGTH_SHORT).show();
}
public class LocalBinder extends Binder {
LocalService getService() {
// Return this instance of LocalService so clients can call public methods
return LocalService.this;
}
}
}
local servcie 的代码如上，在onBinder方法中返回binder，binder包含了service的句柄，客户端得到句柄以后就可以调用servcie的公共方法了，这种调用方式是最常见的。
public class LocalServiceTestActivity extends Activity {
static final String TAG = "LocalBinderTestActivity";
ServiceConnection mSc;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mSc = new ServiceConnection(){
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.d(TAG, "service connected");
LocalService ss = ((LocalBinder)service).getService();
ss.sayHelloWorld();
}
@Override
public void onServiceDisconnected(ComponentName name) {
Log.d(TAG, "service disconnected");
}
};
}
@Override
protected void onStart() {
super.onStart();
Log.d(TAG, this.getApplicationContext().getPackageCodePath());
Intent service = new Intent(this.getApplicationContext(),LocalService.class);
this.bindService(service, mSc, Context.BIND_AUTO_CREATE);
}
@Override
protected void onStop() {
super.onStop();
//must unbind the service otherwise the ServiceConnection will be leaked.
<span style="color: rgb(255, 0, 0); ">this.unbindService(mSc);</span>
}
}
需要注意的是在onStop中要解绑定service, 否则会造成内存泄露的问题。
2. 我们再看一下与另外一个进程中的service进行通信的问题（跨进程通信！）。
如何将servcie运行在另外一个进程呢？在manifest 里面配置个属性就行了。
android:process=":remote" , 代表这个service运行在同一个应用程序的不同进程中。
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.ckt.wangxin"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".LocalServiceTestActivity"
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=".LocalService"></service>
<!-- android:process=":remote" specify this service run in
another process in the same application. -->
<service android:name=".RemoteService" android:process=":remote"></service>
<activity android:name="RemoteServiceTestActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
public class RemoteServiceTestActivity extends Activity {
static final String TAG = "RemoteServiceTestActivity";
ServiceConnection mSc;
public static final int SAY_HELLO_TO_CLIENT = 0;
/**
* Handler of incoming messages from service.
*/
class IncomingHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case SAY_HELLO_TO_CLIENT:
Toast.makeText(RemoteServiceTestActivity.this.getApplicationContext(), "Hello World Remote Client!",
Toast.LENGTH_SHORT).show();
break;
default:
super.handleMessage(msg);
}
}
}
Messenger messenger_reciever = new Messenger(new IncomingHandler());
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mSc = new ServiceConnection(){
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.d(TAG, "service connected");
<span style="color: rgb(204, 0, 0); ">Messenger messenger = new Messenger(service);
Message msg = new Message();
msg.what = RemoteService.MSG_SAY_HELLO;</span>
msg.replyTo = messenger_reciever;
try {
<span style="color: rgb(255, 0, 0); ">messenger.send(msg);</span>
} catch (RemoteException e) {
e.printStackTrace();
}
}
@Override
public void onServiceDisconnected(ComponentName name) {
Log.d(TAG, "service disconnected");
}
};
}
@Override
protected void onStart() {
super.onStart();
Log.d(TAG, this.getApplicationContext().getPackageCodePath());
Intent service = new Intent(this.getApplicationContext(),RemoteService.class);
this.bindService(service, mSc, Context.BIND_AUTO_CREATE);
}
@Override
protected void onStop() {
super.onStop();
//must unbind the service otherwise the ServiceConnection will be leaked.
this.unbindService(mSc);
}
}
获得service端传来的binder，用来构建一个Messenger向service发送消息。
public class RemoteService extends Service {
public static final int MSG_SAY_HELLO = 0;
@Override
public IBinder onBind(Intent intent) {
<span style="color: rgb(204, 0, 0); "> return messager.getBinder();</span>
}
Handler IncomingHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
if(msg.replyTo != null){
Message msg_client = this.obtainMessage();
msg.what = RemoteServiceTestActivity.SAY_HELLO_TO_CLIENT;
try {
((Messenger)msg.replyTo).send(msg_client);
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
switch (msg.what) {
case MSG_SAY_HELLO:
Toast.makeText(RemoteService.this.getApplicationContext(), "Hello World Remote Service!",
Toast.LENGTH_SHORT).show();
break;
default:
super.handleMessage(msg);
}
}
};
Messenger messager = new Messenger (IncomingHandler);
}
构建一个Messenger，包含一个handler，然后将messenger的binder传给客户端，客户端可以通过handler再构造一个messenger与service通信，消息在handler里面被处理。
现在是service端单向响应客户端的消息，同理可以做成双向发送消息，实现双向通信。