Android AIDL Callback的使用（配源码）

零、示例说明

本示例，完成的功能是：客户端向服务端注册一个回调，服务端是一个商店shop，当商店里的产品 Product 有变化时，调用回调向通知客户端，什么商品更新了。

一、完整源代码

完整源码链接: https://github.com/jx0260/TestGradle

二、实现步骤

2.1 定义实体

定义 Product.aidl

// Product.aidl
package com.example.testgradle;

// Declare any non-default types here with import statements

parcelable Product;
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对应的实体类：

package com.example.testgradle;

import android.os.Parcel;
import android.os.Parcelable;

public class Product implements Parcelable {

    private String no;
    private String name;

    public String getNo() {
        return no;
    }

    public void setNo(String no) {
        this.no = no;
    }

    public String getName() {
        return name;
    }

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

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

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(this.no);
        dest.writeString(this.name);
    }

    public void readFromParcel(Parcel source) {
        this.no = source.readString();
        this.name = source.readString();
    }

    public Product() {
    }

    protected Product(Parcel in) {
        this.no = in.readString();
        this.name = in.readString();
    }

    public static final Creator<Product> CREATOR = new Creator<Product>() {
        @Override
        public Product createFromParcel(Parcel source) {
            return new Product(source);
        }

        @Override
        public Product[] newArray(int size) {
            return new Product[size];
        }
    };
}
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定义Callback AIDL，此 IShopProductCallback 将会注册到服务端去。

// IShopProductCallback.aidl
package com.example.testgradle;
import com.example.testgradle.Product;

// Declare any non-default types here with import statements

interface IShopProductCallback {
    oneway void onProductChanged(in Product product);
}
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定义服务端 IShopAidlInterface.aidl，里面有一个registerCallback的方法

// IShopAidlInterface.aidl
package com.example.testgradle;
import com.example.testgradle.IShopProductCallback;

// Declare any non-default types here with import statements

interface IShopAidlInterface {

    String getProductInfo(int productNo);

    void buyProduct1(int productNo, String address);

    oneway void registerCallback(in IShopProductCallback callback);

}
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2.2 Make project 生成相应的 AIDL实现类

客户端：

服务端：

2.2 编写客户端

Intent serviceIntent = new Intent("com.example.testgradle.ShopService");
serviceIntent.setPackage("com.example.testgradle");
bindService(serviceIntent, new ServiceConnection() {
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        Log.i(TAG, "onServiceConnected() service=" + service);
        iShopAidlInterface = IShopAidlInterface.Stub.asInterface(service);
        try {
            Log.i(TAG, "Client: register Stub to Server!");
            iShopAidlInterface.registerCallback(new IShopProductCallback.Stub() {
                @Override
                public void onProductChanged(Product product) throws RemoteException {
                    Log.i(TAG, "Client: received product changed -- " + product.getNo() + " name:" + product.getName());
                }
            });
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {

    }
}, BIND_AUTO_CREATE);
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bindService() com.example.testgradle.ShopService ，在 onServiceConnected 回调中，使用拿到的 iShopAidlInterface 对象，调用 registerCallback，注意，此处传入的 callback 是 IShopProductCallback.Stub

public interface IShopProductCallback extends android.os.IInterface
{
  /** Local-side IPC implementation stub class. */
  public static abstract class Stub extends android.os.Binder
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IShopProductCallback.Stub 继承了 Binder，实际上此处将 IShopProductCallback 的实现传进了参数，到达服务端。服务端拿到的是 IShopProductCallback.Stub.Proxy，这里就会有一种服务端变成客户端的感觉。实际上确实如此，在使用Callback的时候 服务端对于Callback来说 确实就变成了客户端，将变化的product 提交到服务端（也就是业务上的客户端）
此处，引用的“客户端”，“服务端”是有两套意思，一套是指我们总体业务的 客户端、服务端，另一套是指对于callback来说，程序实现的 客户端、服务端。

2.3 编写服务端

package com.example.testgradle;

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

import javax.security.auth.login.LoginException;

public class ShopService extends Service {
    private String TAG = "ShopService";
    private IShopProductCallback mCallback;

    public ShopService() {
    }

    private IShopAidlInterface.Stub mBinder = new IShopAidlInterface.Stub() {
        @Override
        public void registerCallback(IShopProductCallback callback) throws RemoteException {
            Log.i(TAG, "Server: registerCallback() this callback obj is a proxy!");
            mCallback = callback;

            mHandler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    Product product = new Product();
                    product.setNo("No.0001");
                    product.setName("banana");
                    try {
                        Log.i(TAG, "Server: the proxy obj invoke onProductChanged, pass the product to the client!");
                        mCallback.onProductChanged(product);
                    } catch (RemoteException e) {
                        e.printStackTrace();
                    }
                }
            }, 20000);
        }
    };

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }
}
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服务端 public void registerCallback(IShopProductCallback callback) 拿到客户端传来的 callback其实是一个proxy 存到mCallback 本地变量中，20秒后，创建一个变化的Product 调用 mCallback.onProductChanged(product); 将商品信息回调给客户端。

2.4 运行

日志打印：

com.example.testgradle I/ShopService: Server: registerCallback() this callback obj is a proxy!

com.example.testgradle I/ShopService: Server: the proxy obj invoke onProductChanged, pass the product to the client!
com.example.clientdemo I/ClientActivity: Client: received product changed -- No.0001 name:banana
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