Android四大组件之Service:远程service

远程service

AIDL

每个应用程序都运行在自己的独立进程中，
并且可以启动另一个应用进程的服务，
而且经常需要在不同的进程间传递数据对象。

在Android平台，一个进程不能直接访问另一个进程的内存空间，
所以要想对话，需要将对象分解成操作系统可以理解的基本单元(例如基本数据类型)，
并且有序的通过进程边界。

AIDL (Android Interface Definition Language) 
  用于生成可以在Android设备上两个进程之间
  进行进程间通信(interprocess communication, IPC)的代码。

如果在一个进程中（例如Activity）要调用另一个
进程中（例如Service）对象的操作，就可以使用AIDL生成可序列化的参数。

练习例子

首先定义AIDL接口
这个AIDL接口和接口的类很像,我们可以先定义一个这样的接口
然后再进行适当的修改就可以了

创建文件：IStudentService.aidl

  package com.example.service;
  import com.example.service.Student;
  interface IStudentService 
  {
    Student getStudentById(int id);
  }

编写AIDL需要注意:
1.接口名和aidl文件名相同.
2.接口和方法前不用加访问权限修饰符public,private,protected等,也不能用final,static.
3.aidl默认支持的类型包话java基本类型(int,long,boolean等)和(String,List,Map,CharSequence),
  使用这些类型时不需要import声明.对于List和Map中的元素类型必须是aidl支持的类型.
  如果使用自定义类型作为参数或返回值,自定义类型必须实现Parcelable接口.
4.自定义类型和aidl生成的其它接口类型在aidl描述文件中,应该显式import,
  即便在该类和定义的包在同一个包中.
5.在aidl文件中所有非Java基本类型参数必须加上in、out、inout标记,
  以指明参数是输入参数、输出参数还是输入输出参数.
6.Java原始类型默认的标记为in,不能为其它标记.

然后创建自定义类型Student

package com.example.service;

import android.os.Parcel;
import android.os.Parcelable;
import android.util.Log;

public class Student implements Parcelable
{

  private int id;
  private String name;
  private double price;

  @Override
  public int describeContents()
  {
    return 0;
  }
  
  // 将当前对象的属性数据打成包: 写到包对象中
  @Override
  public void writeToParcel(Parcel dest, int flags)
  {
    Log.e("TAG", "打包 writeToParcel()");
    // id
    dest.writeInt(id);
    // name
    dest.writeString(name);
    // price
    dest.writeDouble(price);
  }
  
  // 添加一个静态成员,名为CREATOR,该对象实现了Parcelable.Creator接口
  public static final Parcelable.Creator<Student> CREATOR = new Parcelable.Creator<Student>()
  {
    
    // 解包: 读取包中的数据并封装成对象
    @Override
    public Student createFromParcel(Parcel source)
    {
      Log.e("TAG", "解包 createFromParcel()");
      // id
      int id = source.readInt();
      // name
      String name = source.readString();
      // price
      double price = source.readDouble();
      
      return new Student(id, name, price);
    }
    
    // 返回一个指定大小的对象容器
    @Override
    public Student[] newArray(int size)
    {
      return new Student[size];
    }
  };
  
  public Student(int id, String name, double price)
  {
    super();
    this.id = id;
    this.name = name;
    this.price = price;
  }

  public Student()
  {
    super();
  }

  public int getId()
  {
    return id;
  }

  public void setId(int id)
  {
    this.id = id;
  }

  public String getName()
  {
    return name;
  }

  public void setName(String name)
  {
    this.name = name;
  }

  public double getPrice()
  {
    return price;
  }

  public void setPrice(double price)
  {
    this.price = price;
  }

  @Override
  public String toString()
  {
    return "Student [id=" + id + ", name=" + name + ", price=" + price+ "]";
  }
}

然后定义自定义类型的AIDL接口 

创建文件：Student.aidl

package com.example.service;
parcelable Student;

然后会自动生成一个通信接口类
粘出来给看看吧

/*
 * This file is auto-generated.  DO NOT MODIFY.
 * Original file: E:\\Android\\WorkSpace\\Service\\src\\com\\example\\service\\IStudentService.aidl
 */
package com.example.service;

public interface IStudentService extends android.os.IInterface
{
  /** Local-side IPC implementation stub class. */
  public static abstract class Stub extends android.os.Binder implements
      com.example.service.IStudentService
  {
    private static final java.lang.String DESCRIPTOR = "com.example.service.IStudentService";

    /** Construct the stub at attach it to the interface. */
    public Stub()
    {
      this.attachInterface(this, DESCRIPTOR);
    }

    /**
     * Cast an IBinder object into an com.example.service.IStudentService
     * interface, generating a proxy if needed.
     */
    public static com.example.service.IStudentService asInterface(
        android.os.IBinder obj)
    {
      if ((obj == null))
      {
        return null;
      }
      android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
      if (((iin != null) && (iin instanceof com.example.service.IStudentService)))
      {
        return ((com.example.service.IStudentService) iin);
      }
      return new com.example.service.IStudentService.Stub.Proxy(obj);
    }

    @Override
    public android.os.IBinder asBinder()
    {
      return this;
    }

    @Override
    public boolean onTransact(int code, android.os.Parcel data,
        android.os.Parcel reply, int flags)
        throws android.os.RemoteException
    {
      switch (code)
      {
      case INTERFACE_TRANSACTION:
      {
        reply.writeString(DESCRIPTOR);
        return true;
      }
      case TRANSACTION_getStudentById:
      {
        data.enforceInterface(DESCRIPTOR);
        int _arg0;
        _arg0 = data.readInt();
        com.example.service.Student _result = this
            .getStudentById(_arg0);
        reply.writeNoException();
        if ((_result != null))
        {
          reply.writeInt(1);
          _result.writeToParcel(reply,
              android.os.Parcelable.PARCELABLE_WRITE_RETURN_VALUE);
        } else
        {
          reply.writeInt(0);
        }
        return true;
      }
      }
      return super.onTransact(code, data, reply, flags);
    }

    private static class Proxy implements
        com.example.service.IStudentService
    {
      private android.os.IBinder mRemote;

      Proxy(android.os.IBinder remote)
      {
        mRemote = remote;
      }

      @Override
      public android.os.IBinder asBinder()
      {
        return mRemote;
      }

      public java.lang.String getInterfaceDescriptor()
      {
        return DESCRIPTOR;
      }

      @Override
      public com.example.service.Student getStudentById(int id)
          throws android.os.RemoteException
      {
        android.os.Parcel _data = android.os.Parcel.obtain();
        android.os.Parcel _reply = android.os.Parcel.obtain();
        com.example.service.Student _result;
        try
        {
          _data.writeInterfaceToken(DESCRIPTOR);
          _data.writeInt(id);
          mRemote.transact(Stub.TRANSACTION_getStudentById, _data,
              _reply, 0);
          _reply.readException();
          if ((0 != _reply.readInt()))
          {
            _result = com.example.service.Student.CREATOR
                .createFromParcel(_reply);
          } else
          {
            _result = null;
          }
        } finally
        {
          _reply.recycle();
          _data.recycle();
        }
        return _result;
      }
    }

    static final int TRANSACTION_getStudentById = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
  }

  public com.example.service.Student getStudentById(int id)
      throws android.os.RemoteException;
}

下一步是:
  在Service类中使用生成的类实现业务方法
  
package com.example.service;

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

public class MyRemoteService extends Service
{

  @Override
  public IBinder onBind(Intent intent)
  {
    Log.e("TAG", "onBind()");
    return new StudentService();
  }

  @Override
  public boolean onUnbind(Intent intent)
  {
    Log.e("TAG", "onUnbind()");
    return super.onUnbind(intent);
  }

  // 处理Student相关的业务逻辑类
  class StudentService extends IStudentService.Stub
  {
    @Override
    public Student getStudentById(int id) throws RemoteException
    {
      Log.e("TAG", "Service getStudentById() " + id);
      return new Student(id, "jane", 10000000);
    }
  }

}

然后再到客户端进行编码的了
首先复制服务端AIDL的相关定义
自动生成一个通信接口类
在Activity中bind远程Service，并调用业务方法

  public void bindRemoteService(View v)
  {

    Intent intent = new Intent("com.example.service.MyRemoteService.Action");
    if (conn == null)
    {
      conn = new ServiceConnection()
      {
        @Override
        public void onServiceDisconnected(ComponentName name)
        {

        }

        @Override
        public void onServiceConnected(ComponentName name,IBinder service)
        {
          Log.e("TAG", "onServiceConnected()");
          studentService = IStudentService.Stub.asInterface(service);
        }
      };
      bindService(intent, conn, Context.BIND_AUTO_CREATE);
      Toast.makeText(this, "绑定Service", 0).show();
    } else
    {
      Toast.makeText(this, "已经绑定Service", 0).show();
    }
  }

到这里是终于结束了

总的代码

服务端

package com.example.service;

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

public class MyRemoteService extends Service
{

  @Override
  public IBinder onBind(Intent intent)
  {
    Log.e("TAG", "onBind()");
    return new StudentService();
  }

  @Override
  public boolean onUnbind(Intent intent)
  {
    Log.e("TAG", "onUnbind()");
    return super.onUnbind(intent);
  }

  // 处理Student相关的业务逻辑类
  class StudentService extends IStudentService.Stub
  {
    @Override
    public Student getStudentById(int id) throws RemoteException
    {
      Log.e("TAG", "Service getStudentById() " + id);
      return new Student(id, "jane", 10000000);
    }
  }

}

package com.example.service;

import android.os.Parcel;
import android.os.Parcelable;
import android.util.Log;

public class Student implements Parcelable
{

  private int id;
  private String name;
  private double price;

  @Override
  public int describeContents()
  {
    return 0;
  }
  
  // 将当前对象的属性数据打成包: 写到包对象中
  @Override
  public void writeToParcel(Parcel dest, int flags)
  {
    Log.e("TAG", "打包 writeToParcel()");
    // id
    dest.writeInt(id);
    // name
    dest.writeString(name);
    // price
    dest.writeDouble(price);
  }
  
  // 添加一个静态成员,名为CREATOR,该对象实现了Parcelable.Creator接口
  public static final Parcelable.Creator<Student> CREATOR = new Parcelable.Creator<Student>()
  {
    
    // 解包: 读取包中的数据并封装成对象
    @Override
    public Student createFromParcel(Parcel source)
    {
      Log.e("TAG", "解包 createFromParcel()");
      // id
      int id = source.readInt();
      // name
      String name = source.readString();
      // price
      double price = source.readDouble();
      
      return new Student(id, name, price);
    }
    
    // 返回一个指定大小的对象容器
    @Override
    public Student[] newArray(int size)
    {
      return new Student[size];
    }
  };
  
  public Student(int id, String name, double price)
  {
    super();
    this.id = id;
    this.name = name;
    this.price = price;
  }

  public Student()
  {
    super();
  }

  public int getId()
  {
    return id;
  }

  public void setId(int id)
  {
    this.id = id;
  }

  public String getName()
  {
    return name;
  }

  public void setName(String name)
  {
    this.name = name;
  }

  public double getPrice()
  {
    return price;
  }

  public void setPrice(double price)
  {
    this.price = price;
  }

  @Override
  public String toString()
  {
    return "Student [id=" + id + ", name=" + name + ", price=" + price+ "]";
  }
}

package com.example.service;
import com.example.service.Student;
interface IStudentService 
{
  Student getStudentById(int id);
}

package com.example.service;
parcelable Student;

对应下面四个文件

客户端

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="bindRemoteService"
        android:text="bind remote Service" />

    <EditText
        android:id="@+id/et_aidl_id"
        android:layout_width="fill_parent"
        android:layout_height="50dip"
        android:hint="学员ID"
        android:text="3" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="invokeRemote"
        android:text="调用远程服务端的方法" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="unbindRemoteService"
        android:text="unbind remote Service" />

</LinearLayout>

package com.example.client;

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.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import com.example.service.IStudentService;
import com.example.service.Student;

public class MainActivity extends Activity
{
  private EditText et_aidl_id;

  @Override
  protected void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    et_aidl_id = (EditText) findViewById(R.id.et_aidl_id);
  }

  private ServiceConnection conn;
  private IStudentService studentService;

  public void bindRemoteService(View v)
  {

    Intent intent = new Intent("com.example.service.MyRemoteService.Action");
    if (conn == null)
    {
      conn = new ServiceConnection()
      {
        @Override
        public void onServiceDisconnected(ComponentName name)
        {

        }

        @Override
        public void onServiceConnected(ComponentName name,IBinder service)
        {
          Log.e("TAG", "onServiceConnected()");
          studentService = IStudentService.Stub.asInterface(service);
        }
      };
      bindService(intent, conn, Context.BIND_AUTO_CREATE);
      Toast.makeText(this, "绑定Service", 0).show();
    } else
    {
      Toast.makeText(this, "已经绑定Service", 0).show();
    }
  }

  public void invokeRemote(View v) throws RemoteException
  {
    if (studentService != null)
    {
      int id = Integer.parseInt(et_aidl_id.getText().toString());
      Student student = studentService.getStudentById(id);
      Toast.makeText(this, student.toString(), 0).show();
    }
  }

  public void unbindRemoteService(View v)
  {
    if (conn != null)
    {
      unbindService(conn);
      conn = null;
      studentService = null;
      Toast.makeText(this, "解绑Service", 0).show();
    } else
    {
      Toast.makeText(this, "还未绑定Service", 0).show();
    }
  }
}

还需要导入服务端AIDL的相关定义
比如
  Student.java
  IStudentService.aidl
  Student.aidl

Android四大组件之Service:远程service

远程service

AIDL

练习例子

总的代码

服务端

客户端

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