AudioManager am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);

static {
    ......
    // 将AudioManager加入SYSTEM_SERVICE_MAP中，调用getSystemService时，
    // 就会从SYSTEM_SERVICE_MAP得到AudioManager
    registerService(AUDIO_SERVICE, new ServiceFetcher() {
        public Object createService(ContextImpl ctx) {
          return new AudioManager(ctx);
        }});
    ......
}

private static IAudioService getService()
{
    if (sService != null) {
      return sService;
    }
    // 从ServiceManager中获取Binder
    IBinder b = ServiceManager.getService(Context.AUDIO_SERVICE);
    // 将Binder转化成IAudioService,方便调用
    sService = IAudioService.Stub.asInterface(b);
    return sService;
}

package com.test.lib;
interface IMyService {
  void setValue(int val);
  int getValue();
}

package com.test.myservice;
import android.os.RemoteException;
import com.test.lib.IMyService;
public class MyService extends IMyService.Stub {
  private int value;
  @Override
  public void setValue(int val) throws RemoteException {
    this.value = val;
  }
  @Override
  public int getValue() throws RemoteException {
    return value;
  }
}

package com.test.myservice;
import android.app.Application;
import android.os.ServiceManager;
public class MyServiceApplication extends Application{
  @Override
  public void onCreate() {
    super.onCreate();
    ServiceManager.addService("MYSERVICE", new MyService());
  }
}

<application
    android:name=".MyServiceApplication"  //指定Application为我们创建的MyServiceApplication
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:persistent="true"       // 加上persistent=ture，ActivityManager创建的时候，就会创建该应用的进程，并调用MyServiceApplication的onCreate方法
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

package com.test.lib;
import android.os.RemoteException;
import android.os.ServiceManager;
public class MyManager {
  private static MyManager instance;
  private IMyService myservice;
  public static MyManager getInstance() {
    if (instance == null) {
      instance = new MyManager();
    }
    return instance;
  }
  private MyManager() {
    // 从ServiceManager中获取服务
    myservice = IMyService.Stub.asInterface(ServiceManager.getService("MYSERVICE"));
  }
  public void setValue(int value) throws RemoteException {
    myservice.setValue(value);
  }
  public int getValue() throws RemoteException {
    return myservice.getValue();
  }
}

package com.test.client;
import java.util.Random;
import android.app.Activity;
import android.content.Context;
import android.media.AudioManager;
import android.os.Bundle;
import android.os.RemoteException;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import com.test.binder.client.R;
import com.test.lib.MyManager;
public class MainActivity extends Activity implements OnClickListener {
  MyManager myManager;
  Button btnSetValue;
  Button btnGetValue;
  TextView tvValue;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    AudioManager am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
    setContentView(R.layout.activity_main);
    btnSetValue = (Button) findViewById(R.id.btn_set_value);
    btnGetValue = (Button) findViewById(R.id.btn_get_value);
    tvValue = (TextView) findViewById(R.id.tv_value);
    // 获取MyManager
    myManager = MyManager.getInstance();
  }
  @Override
  public void onClick(View view) {
    switch (view.getId()) {
    case R.id.btn_set_value:
      int value = new Random().nextInt();
      try {
        myManager.setValue(value);
        Toast.makeText(this, "set value to "+value+ " success!", 0).show();
      } catch (RemoteException e) {
        e.printStackTrace();
        Toast.makeText(this, "set value fail!", 0).show();
      }
      break;
    case R.id.btn_get_value:
      try {
        tvValue.setText("value:"+myManager.getValue());
      } catch (RemoteException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
      break;
    default:
      break;
    }
  }
}