Service的onServiceConnected没有被调用

Service是一种运行在后台的服务，一般很少与用户交互，所以没有可视化界面。
我们可以通过startService() 或者使用bindService()方法来绑定一个存在的service。

bindService是异步调用和Service进行绑定,
如果绑定成功, 则会调用ServiceConnection的onServiceConnected。

当调用bindService方法后就会回调Activity的onServiceConnected，在这个方法中会向Activity中传递一个IBinder的实例，Acitity需要保存这个实例。

在Service中需要创建一个实现IBinder的内部类(这个内部类不一定在Service中实现，但必须在Service中创建它)。

在OnBind（）方法中需返回一个IBinder实例，不然onServiceConnected方法不会调用。

import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class ServiceActivity extends Activity {
/** Called when the activity is first created. */
private Button start;
private Button stop;
private Button bind;
private Button unbind;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
start =(Button) findViewById(R.id.start);
stop = (Button) findViewById(R.id.stop);
bind = (Button) findViewById(R.id.bind);
unbind = (Button) findViewById(R.id.unbind);
//启动一个service
start.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent();
System.out.println("start....");
intent.setAction("com.shao.service.action.MyService");
startService(intent);
}
});
//结束一个service
stop.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent();
System.out.println("stop....");
intent.setAction("com.shao.service.action.MyService");
stopService(intent);
}
});

//绑定一个service
bind.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent();
System.out.println("bind..");
intent.setAction("com.shao.service.action.MyService");
bindService(intent, conn, BIND_AUTO_CREATE);
}
});
//解除绑定的service
unbind.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent();
System.out.println("unbind..");
intent.setAction("com.shao.service.action.MyService");
unbindService(conn);
}
});
}

private ServiceConnection conn = new ServiceConnection() {

@Override
public void onServiceDisconnected(ComponentName arg0) {
// TODO Auto-generated method stub
Toast.makeText(ServiceActivity.this,"disconn successful" ,Toast.LENGTH_LONG);
}

@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// TODO Auto-generated method stub
Toast.makeText(ServiceActivity.this,"conn successful" ,Toast.LENGTH_LONG);
}
};
}

MyService文件：

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.os.Parcel;
import android.widget.Toast;

public class MyService extends Service {
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
System.out.println("onBind.....");
IBinder result = null;
if ( null == result ) result = new MyBinder() ;
Toast.makeText(this, "onBind",Toast.LENGTH_LONG);
return result;
}

@Override
public void onCreate() {
// TODO Auto-generated method stub
super.onCreate();
System.out.println("onCreate.....");
Toast.makeText(this, "onCreate",Toast.LENGTH_LONG);
}

@Override
public void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
System.out.println("onDestory.....");
Toast.makeText(this, "onDestroy",Toast.LENGTH_LONG);
}

@Override
public void onStart(Intent intent, int startId) {
// TODO Auto-generated method stub
super.onStart(intent, startId);
System.out.println("onStart...");
Toast.makeText(this, "onStart",Toast.LENGTH_LONG);
}
public class MyBinder extends Binder {
//此方法是为了可以在Acitity中获得服务的实例
public MyService getService() {
return MyService.this;
}

}
}

Service需在mainifest文件中声明:

<service android:name="MyService">

<intent-filter>

<action android:name="com.shao.service.action.MyService"/>

</intent-filter>

</service>