Android开发之Service与Activity数据交互

    Service想要与Activity进行数据交互，首先Activity先得绑定Service.bound service是service 的实现,它允许其他应用程序绑定到它并与之交互。要提供bound service,我们必须实现onBind()回调方法。这个方法返回一个内部对象定义的编程接口,Activity可以使用与Service进行交互。那么具体该如何实现呢，首先我们还是一样先创建一个MyService继承Service。然后如何设置:呢。（1）在你的Service,创建一个Binder实例,返回当前的Service实例以及一个Activity可以调用公共方法。（2）返回这个实例的Binder在onBind()回调方法。（3）在Activity里创建ServiceConnection,在onServiceConnected()回调方法接受Binder,并得到服务器的实例。讲的比较啰嗦哦，我们还是看代码来细细品味吧。


    Service的代码


    [java] view plaincopy


    package com.example.f22_service02;


    import java.util.Random;


    import android.app.Service;


    import android.content.Intent;


    import android.os.Binder;


    import android.os.IBinder;


    import android.os.Parcel;


    import android.os.RemoteException;


    import android.util.Log;


    public class HelloService extends Service {


    private MyBinder binder=new MyBinder();


    public class MyBinder extends Binder{


    public HelloService getService(){


    return HelloService.this;


    //返回Service实例，使主程序能调用该方法


    }


    @Override


    protected boolean onTransact(int code, Parcel data, Parcel reply,


    int flags) throws RemoteException {


    // TODO Auto-generated method stub


    Log.i("TAG", "------>"+data.readInt());


    Log.i("TAG", "------>"+data.readString());


    reply.writeInt(2);


    reply.writeString("Rose");


    return super.onTransact(code, data, reply, flags);


    }


    }


    @Override


    public IBinder onBind(Intent intent) {


    // TODO Auto-generated method stub


    return binder; //回掉方法


    }


    public int getRandom(){


    return new Random().nextInt(100);


    }


    @Override


    public void onCreate() {


    // TODO Auto-generated method stub


    Log.i("TAG", "------>Create");


    super.onCreate();


    }


    @Override


    public boolean onUnbind(Intent intent) {


    // TODO Auto-generated method stub


    Log.i("TAG", "------>Unbind");


    return super.onUnbind(intent);


    }


    }


    Activity的方法


    [java] view plaincopy


    package com.example.f22_service02;


    import com.example.f22_service02.HelloService.MyBinder;


    import android.os.Bundle;


    import android.os.IBinder;


    import android.os.Parcel;


    import android.os.RemoteException;


    import android.annotation.SuppressLint;


    import android.app.Activity;


    import android.content.ComponentName;


    import android.content.Context;


    import android.content.Intent;


    import android.content.ServiceConnection;


    import android.util.Log;


    import android.view.View;


    import android.view.View.OnClickListener;


    import android.widget.Button;


    @SuppressLint("Recycle")


    public class MainActivity extends Activity implements OnClickListener {


    private Button button, button2, button3;


    private MyBinder binder;


    private HelloService helloService;


    @Override


    protected void onCreate(Bundle savedInstanceState) {


    super.onCreate(savedInstanceState);


    setContentView(R.layout.activity_main);


    button = (Button) this.findViewById(R.id.button1);


    button2 = (Button) this.findViewById(R.id.button2);


    button3 = (Button) this.findViewById(R.id.button3);


    button.setOnClickListener(this);


    button2.setOnClickListener(this);


    button3.setOnClickListener(this);


    }


    private ServiceConnection connection = new ServiceConnection() {


    @Override


    public void onServiceDisconnected(ComponentName name) {


    // TODO Auto-generated method stub


    Log.i("ACTIVITY", "---------〉失去绑定");


    }


    @Override


    public void onServiceConnected(ComponentName name, IBinder service) {


    // TODO Auto-generated method stub


    binder = (MyBinder) service; // 绑定Service，并获得Service实例，接下来就可以调用Service中的方法了


    helloService = binder.getService();


    Log.i("ACTIVITY", "---------〉绑定成功");


    }


    };


    @SuppressLint("Recycle")


    @Override


    public void onClick(View v) {


    // TODO Auto-generated method stub


    switch (v.getId()) {


    case R.id.button1:


    //绑定Service


    Intent intent=new Intent(MainActivity.this,HelloService.class);


    bindService(intent, connection, Context.BIND_AUTO_CREATE);//第三个参数是一个标志显示选项绑定


    break;


    case R.id.button2:


    //实现Activity与Service的数据交互


    //Parcel是一个容器，能包含消息(数据和对象引用),可以通过一个IBinde发送


    Parcel data=Parcel.obtain();


    data.writeInt(helloService.getRandom());


    data.writeString("jack");


    Parcel reply=Parcel.obtain();


    try {


    binder.transact(IBinder.LAST_CALL_TRANSACTION, data, reply, 0);


    } catch (RemoteException e) {


    // TODO Auto-generated catch block


    e.printStackTrace();


    }


    Log.i("ACTIVITY", "----Service回传的值---->"+reply.readInt());


    Log.i("ACTIVITY", "----Service回传的值---->"+reply.readString());


    break;


    case R.id.button3:


    //解除绑定


    unbindService(connection);


    break;


    }


    }


    }