Question

service 能activity交互吗

Answer 1

service 能activity交互,Activity与Service之间交互并播放歌曲

MService：

package com.tiantian.test;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Binder;
import android.os.Environment;
import android.os.IBinder;
import android.util.Log;

public class MService extends Service{
    MyBinder myBinder = new MyBinder();
    private MediaPlayer mediaPlayer;
    
    public class MyBinder extends Binder{
        MService getService(){
            return MService.this;
        }
    }
    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        Log.v("CAT", "onBind");
        return myBinder;
    }

    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
        Log.v("CAT", "onCreate");
        try {
            mediaPlayer = new MediaPlayer();
            mediaPlayer.setDataSource(Environment.getExternalStorageDirectory() + "/mp3/trhxn.mp3");
            mediaPlayer.prepare();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            Log.v("CAT", "fail");
            e.printStackTrace();
        } 
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        Log.v("CAT", "onDestroy");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // TODO Auto-generated method stub
        Log.v("CAT", "onStartCommand");
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public boolean onUnbind(Intent intent) {
        // TODO Auto-generated method stub
        Log.v("CAT", "onUnbind");
        return false;
    }
    
    public void start(){
        mediaPlayer.start();
    }
    public void pause(){
        mediaPlayer.pause();
    }
    public void stop(){
        mediaPlayer.stop();
        mediaPlayer.release();
    }
    public int getDuration(){
        return mediaPlayer.getDuration();
    }
    public int getCurrentPosition(){
        return mediaPlayer.getCurrentPosition();
    }
    public void seekTo(int position){
        mediaPlayer.seekTo(position);
    }
}

MusicPlayActivity：

package com.tiantian.test;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.SeekBar;

public class MusicPlayActivity extends Activity {
    /** Called when the activity is first created. */
    MService mService;
    private ServiceConnection conn = new ServiceConnection(){

        @Override
        public void onServiceConnected(ComponentName arg0, IBinder arg1) {
            // TODO Auto-generated method stub
            mService = ((MService.MyBinder)arg1).getService();
            Log.v("CAT", "getServiced");
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            // TODO Auto-generated method stub
            mService = null;
        }
        
    };
    
    private SeekBar seekBar;
    private Button playBT;
    
    private boolean isPlaying = false;
    private boolean isBinded = false;
    
    private Handler mHandler;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Intent intent = new Intent(MusicPlayActivity.this, MService.class);
        if(!isBinded){
            bindService(intent, conn, BIND_AUTO_CREATE);
            isBinded = true;
        }
        seekBar = (SeekBar) findViewById(R.id.seekBar);
        playBT = (Button) findViewById(R.id.startBT);
        mHandler = new Handler();
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            
            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {}
            
            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {}
            
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress,
                    boolean fromUser) {
                if(fromUser){
                    mService.seekTo((progress*mService.getDuration())/100);
                }
            }
        });
        playBT.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                if(!isPlaying){
                    mService.start();
                    isPlaying = true;
                    playBT.setText("暂停");
                    mHandler.post(seekBarThread);
                }else{
                    mService.pause();
                    isPlaying = false;
                    playBT.setText("播放");
                    mHandler.removeCallbacks(seekBarThread);
                }
            }
        });
        
    }
    
    Runnable seekBarThread = new Runnable() {
        
        @Override
        public void run() {
            // TODO Auto-generated method stub
            seekBar.setProgress((mService.getCurrentPosition()*100)/mService.getDuration());
            mHandler.postDelayed(seekBarThread, 200);
        }
    };
    
}

Answer 2

Activity访问service有两种方式，第一种是通过Ibinder接口实现步骤如下
在Service类中
public class PlayerService extends Service {

private final IBinder binder = new MyBinder();

@Override

public IBinder onBind(Intent intent) {

return binder;

}

public class MyBinder extends Binder {

public PlayerService getService() {

return PlayerService.this;

}

}

}

通过MyBinder内部类得到当前service的实例
在要访问service的activity中

/**
* 在PlayerService类中定义了一个MyBinder类，该类实际上是为了获得PlayerService的对象实例的。
* 在ServiceConnection接口的onServiceConnected方法中的第2个参数是一个IBinder类型的变量，
* 将该参数转换成PlayerService.MyBinder对象，并使用MyBinder类中的getService方法获得PlayerService对象。
* 在获得PlayerService对象后，就可以在Activity中随意操作PlayerService了。
*/

public class PlayerActivity extends Activity{

private PlayerService serviceBinder;

ServiceConnection connection = new ServiceConnection() {

public void onServiceDisconnected(ComponentName name) {

serviceBinder = null;

}

public void onServiceConnected(ComponentName name, IBinder service) {

serviceBinder = ((PlayerService.MyBinder)service).getService();

}

};

}

然后调用bindService() 建立连接。
这里的代码是跳转并绑定service

Intent i=new Intent();
i.setClass(PlayerActivity.this, PlayerService.class);
i.putExtra("mp3info", mp3Info);
i.putExtra("MSG", AppConstant.PalyerMsg.PRE_MSG);
startService(i);
bindService(i, connection, Context.BIND_AUTO_CREATE);

得到serviceBinder后，就可以通过serviceBinder调用service里面的方法了。
第二种方式是通过aidl，具体实现如下
1．建立aidl文件，如果aidl文件的内容是正确的话，ADT会自动生成一个java接口文件(*.java)

2．建立服务类（Service的子类）
3．实现由aidl文件生成的java接口
4．在AndroidManifest.xml文件中配置aidl服务。要注意的是<action>标签中android:name的属性值就是要引用该服务的ID,也就是Intent类的参数值.

1.Aidl文件内容
package net.blogjava.mobile.aidl;

interface IMyService

{

String getValue();

}

2.编写完后会生成一个同名的java文件,这里是IMyService.java我们不需要管这个java文件
3.编写一个MyService类. MyService是Service的子类,在MyService类中定义了一个内嵌类(MyServiceImpl)该类是IMyService.Stub的子类.

package net.blogjava.mobile.aidl;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;

public class MyService extends Service {

public class MyServiceImpl extends IMyService.Stub {
@Override
public String getValue() throws RemoteException {
// TODO Auto-generated method stub
return "Android/OPhone开发讲义";
}

}
@Override
public IBinder onBind(Intent intent) {
return new MyServiceImpl();
}

}
4.在AndroidManifest.xml文件中配置MyService类,因为这里是跨进程访问service所以是用指定action的方式.如果在同一个进程中可以不用过滤的intent-filter,只写一个
<service android:name=".MyService" >这样的就可以了,此处是跨进程所以代码写成这样:

<service android:name=".MyService" >
<intent-filter>
<action android:name="net.blogjava.mobile.aidl.IMyService" />
</intent-filter>
</service>

下面是客户端的代码
1. 将自动生成的IMyService.java文件连同包一起复制到客户端工程项目中
2. 客户端的代码如下(可以参考android 项目示例src目录下ch08_aidlclient和ch08_aidl)

package net.blogjava.mobile;

import net.blogjava.mobile.aidl.IMyService;

import android.app.Activity;

import android.content.ComponentName;

import android.content.Context;

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.TextView;

public class Main extends Activity implements OnClickListener {

private IMyService myService = null;

private Button btnInvokeAIDLService;

private Button btnBindAIDLService;

private TextView textView;

private ServiceConnection serviceConnection = new ServiceConnection() {

@Override

public void onServiceConnected(ComponentName name, IBinder service) {

myService = IMyService.Stub.asInterface(service);

btnInvokeAIDLService.setEnabled(true);

}

@Override

public void onServiceDisconnected(ComponentName name) {

// TODO Auto-generated method stub

}

};

@Override

public void onClick(View view) {

switch (view.getId()) {

case R.id.btnBindAIDLService:

bindService(new Intent("net.blogjava.mobile.aidl.IMyService"),

serviceConnection, Context.BIND_AUTO_CREATE);

break;

case R.id.btnInvokeAIDLService:

try {

textView.setText(myService.getValue());

} catch (Exception e) {

}

break;

}

}

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

btnInvokeAIDLService = (Button) findViewById(R.id.btnInvokeAIDLService);

btnBindAIDLService = (Button) findViewById(R.id.btnBindAIDLService);

btnInvokeAIDLService.setEnabled(false);

textView = (TextView) findViewById(R.id.textview);

btnInvokeAIDLService.setOnClickListener(this);

btnBindAIDLService.setOnClickListener(this);

}

}