android中aidl

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AIDL是一个缩写，全称是Android Interface Definition Language，也就是Android接口定义语言.
设计这门语言的目的是为了实现进程间通信，尤其是在涉及多进程并发情况下的进程间通信。
学习这个是在Service的远程服务调用时会遇到这个问题。

service的调用分本地调用和远程服务调用。本地其实就是同一个应用之间的调用，远程服务调用就是不同应用之间的调用。比如淘宝里的芭芭农场调用支付宝里的芭芭农场，是两个应用之间的调用。

案例：
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:id="@+id/button1"
        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="match_parent"
        android:layout_height="wrap_content"
       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>

服务端，由于是暴露服务，是不用界面的，只要编写好AIDL文件，拷贝一份到客户端，就可以进行调用了。在我们的服务端项目中，同时演示了调用本地的Service

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1. 测试启动本地服务"
        android:textSize="25sp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/button1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="startMyService"
            android:text="启动服务" />

        <Button
            android:id="@+id/button2"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="stopMyService"
            android:text="停止服务" />
    </LinearLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="2.  测试绑定本地服务"
        android:textSize="25sp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="bindMyService"
            android:text="绑定服务" />

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="unbindMyService"
            android:text="解绑服务" />
    </LinearLayout>

</LinearLayout>

处理MainActivity.java

package com.hbk.servicedemo;

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.util.Log;
import android.view.View;
import android.widget.Toast;

import com.hbk.servicedemo.local.MyService;

public class MainActivity extends Activity {
    
    

	@Override
	protected void onCreate(Bundle savedInstanceState) {
    
    
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}
	
	//启动服务
	public void startMyService(View v) {
    
    
		Intent intent = new Intent(this, MyService.class);
		startService(intent);
		Toast.makeText(this, "start service", 0).show();
	}
	
	public void stopMyService(View v) {
    
    
		Intent intent = new Intent(this, MyService.class);
		stopService(intent);
		Toast.makeText(this, "stop service", 0).show();
	}
	
	private ServiceConnection conn;
	//绑定服务
	public void bindMyService(View v) {
    
    
		Intent intent = new Intent(this, MyService.class);
		//创建连接对象
		if(conn==null) {
    
    
			conn = new ServiceConnection() {
    
    
				@Override
				public void onServiceDisconnected(ComponentName name) {
    
    
					Log.e("TAG", "onServiceDisconnected()");
				}
				@Override
				public void onServiceConnected(ComponentName name, IBinder service) {
    
    
					Log.e("TAG", "onServiceConnected()");
				}
			};
			//绑定Service
			bindService(intent, conn, Context.BIND_AUTO_CREATE);
			
			Toast.makeText(this, "bind service", 0).show();
		} else {
    
    
			Toast.makeText(this, "已经bindservice", 0).show();
		}
		
	}
	
	//解绑服务
	public void unbindMyService(View v) {
    
    
		if(conn!=null) {
    
    
			unbindService(conn);
			conn = null;
			Toast.makeText(this, "unbind service", 0).show();
		} else {
    
    
			Toast.makeText(this, "还没有bindservice", 0).show();
		}
		
	}
	
	//在Activity死亡之前调用
	@Override
	protected void onDestroy() {
    
    
		super.onDestroy();
		if(conn!=null) {
    
    
			unbindService(conn);
			conn = null;
		}
	}
}

本地Service,主要重点掌握如下API即可
.startService(Intent service)
stopService(Intent name)
bindService(Intent service, ServiceConnection conn, int flags)
unbindService(ServiceConnection conn)

远程Service,先定义AIDL文件，如我们新建IStudentService.aidl(可以新建interface，然后重命名)
IStudentService.aidl，同包下的类也需要import(注意)

package com.hbk.servicedemo.remote;
import com.hbk.servicedemo.remote.Student;
interface IStudentService {
    
    

	 Student getStudentById(int id);
}

第二步，实体类需要实现Parcelable接口
Student.java

package com.hbk.servicedemo.remote;

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;

	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 + "]";
	}

	public Student(int id, String name, double price) {
    
    
		super();
		this.id = id;
		this.name = name;
		this.price = price;
	}

	public Student() {
    
    
		super();
		// TODO Auto-generated constructor stub
	}

	@Override
	public int describeContents() {
    
    
		return 0;
	}

	@Override
	public void writeToParcel(Parcel dest, int flags) {
    
    
		Log.e("TAG", "打包 writeToParcel()");
		dest.writeInt(id);
		dest.writeString(name);
		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>() {
    
    

		@Override
		public Student createFromParcel(Parcel source) {
    
    
			// id
			int id = source.readInt();
			// name
			String name = source.readString();
			// price
			double price = source.readDouble();
			return new Student(id, name, price);
		}

		@Override
		public Student[] newArray(int size) {
    
    
			return new Student[size];
		}

	};
}

固定模式，public static final Parcelable.Creator<Student> CREATOR，名字一定叫CREATOR，注意序列化的顺序，即打包读写顺序要一致。
第三步，新建Student.aidl文件

package com.hbk.servicedemo.remote;
parcelable Student;

清单文件中注册service

<service android:name="com.hbk.servicedemo.local.MyService"/>
        <service android:name="com.hbk.servicedemo.remote.MyRemoteService">
            <intent-filter>
                <action android:name="com.hbk.servicedemo.remote.MyRemoteService.Action"/>
            </intent-filter>
        </service>

定义Action，主要是为了给客户端进行调用
客户端处理Activity

package com.hbk.servicedemoclient;

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.hbk.servicedemo.remote.IStudentService;
import com.hbk.servicedemo.remote.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;
	// 绑定远程服务
	public void bindRemoteService(View v){
    
    
		Intent intent = new Intent("com.hbk.servicedemo.remote.MyRemoteService.Action");
		if(conn == null){
    
    
			conn = new ServiceConnection() {
    
    
				
				@Override
				public void onServiceDisconnected(ComponentName name) {
    
    
					// TODO Auto-generated method stub
					
				}
				
				@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();
		}
	}
	
	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();
		}
	}
}

绑定的时候，传入服务端的action
Intent intent = new Intent(“com.hbk.servicedemo.remote.MyRemoteService.Action”);
服务连接的时候，初始化业务服务

@Override
public void onServiceConnected(ComponentName name, IBinder service) {
    
    
	Log.e("TAG", "onServiceConnected()");
	studentService = IStudentService.Stub.asInterface(service);
}

测试