Binder系列之AIDL的使用

AIDL是Android進(jìn)程IPC定義語言的縮寫，主要是用來定義進(jìn)程間通信的接口。本文使用一個(gè)Demo程序來說明AIDL的使用，demo工程的分2個(gè)module:

  1. App "客戶端"，發(fā)送網(wǎng)絡(luò)請(qǐng)求到server端，并且在接收到來自于server的數(shù)據(jù)后展示結(jié)果到UI。
  2. Server "服務(wù)端"負(fù)責(zé)執(zhí)行耗時(shí)的網(wǎng)絡(luò)請(qǐng)求。

以上2個(gè)module運(yùn)行于2個(gè)獨(dú)立的進(jìn)程當(dāng)中，進(jìn)程間的通信依靠aidl接口。

Server

首先，所有的aidl接口都由server端定義，目錄結(jié)構(gòu)如下：


server的文件結(jié)構(gòu)

我們服務(wù)進(jìn)程需要提供一個(gè)訪問入口給客戶進(jìn)程，所以首先定義了IPostInterface.aidl，內(nèi)容如下：

Paste_Image.png

post方法接受一個(gè)Request請(qǐng)求，setResponseInterface接受一個(gè)訪問客戶進(jìn)程的接口，該接口是用于上報(bào)網(wǎng)絡(luò)任務(wù)的結(jié)果給客戶進(jìn)程的。
因?yàn)槭褂昧俗远x類Request，所以我們需要?jiǎng)?chuàng)建一個(gè)aidl文件，用于聲明Request，如下 aidl文件名要和Request相同:

Paste_Image.png

接下來，還需要實(shí)現(xiàn)Request，Request必須實(shí)現(xiàn)Parcelable接口，如下:

package www.seven.com.server;

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

/**
 * @author Seven in 2017-01-07
 */

public class Request implements Parcelable {

    public void setRequestId(int requestId) {
        this.mRequestId = requestId;
    }

    public void setUrl(String url) {
        this.mUrl = url;
    }

    public int getRequestId() {
        return mRequestId;
    }

    public String getUrl() {
        return mUrl;
    }

    // 請(qǐng)求的唯一id
    private int mRequestId;

    // 請(qǐng)求的url
    private String mUrl;

    protected Request(Parcel in) {
        mUrl = in.readString();
        mRequestId = in.readInt();
    }

    public Request(int reqId, String url) {
        mRequestId = reqId;
        mUrl = url;
    }

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

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

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

    @Override
    public void writeToParcel(Parcel parcel, int i) {
        parcel.writeString(mUrl);
        parcel.writeInt(mRequestId);
    }
}

上面的實(shí)現(xiàn)過程，都是模板代碼來的，值得注意的地方是從Parcel里面讀取數(shù)據(jù)的順序，也和寫入數(shù)據(jù)的順序一致。

setResponseInterface需要提交一個(gè)aidl接口給服務(wù)進(jìn)程，好讓服務(wù)進(jìn)程能夠及時(shí)反饋網(wǎng)絡(luò)請(qǐng)求的結(jié)果，改aidl接口定義如下:

Paste_Image.png

該接口接受成功和失敗的消息，當(dāng)網(wǎng)絡(luò)任務(wù)執(zhí)行成功時(shí)，需要返回一個(gè)Response實(shí)例給客戶進(jìn)程，類似Request，我們也需要定義Response的aidl聲明：

// Response.aidl
package www.seven.com.server;

parcelable Response;

同樣，我們也需要實(shí)現(xiàn)Response類：

package www.seven.com.server;

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

/**
 * @author Seven in 2017-01-07
 */

public class Response implements Parcelable {

    // 這個(gè)應(yīng)答對(duì)應(yīng)的請(qǐng)求。
    private Request mRequest;

    private int mStatusCode;

    private String mResponseStr;

    public Request getRequest() {
        return mRequest;
    }

    public int getStatusCode() {
        return mStatusCode;
    }

    public String getResponseStr() {
        return mResponseStr;
    }

    protected Response(Parcel in) {
        mRequest = in.readParcelable(getClass().getClassLoader());
        mStatusCode = in.readInt();
        mResponseStr = in.readString();
    }

    public Response(Request request, int code, String resStr) {
        mRequest = request;
        mStatusCode = code;
        mResponseStr = resStr;
    }

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

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

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

    @Override
    public void writeToParcel(Parcel parcel, int i) {
        parcel.writeParcelable(mRequest, i);
        parcel.writeInt(mStatusCode);
        parcel.writeString(mResponseStr);
    }
}

因?yàn)橐粋€(gè)Response會(huì)保存著一個(gè)對(duì)應(yīng)的Request，所以這里需要注意下載Parcelable里面讀寫另外一個(gè)Parcelable的實(shí)現(xiàn)方式。

接下來是網(wǎng)絡(luò)任務(wù)的實(shí)現(xiàn)，在這里，執(zhí)行網(wǎng)絡(luò)請(qǐng)求，可以使用第三方庫，也可以使用系統(tǒng)API實(shí)現(xiàn)，我現(xiàn)在只是模擬一個(gè)耗時(shí)任務(wù)而已。NetworkTask實(shí)現(xiàn)如下，該Task接受一個(gè)Request，并將結(jié)果提交給Handler。

package www.seven.com.server.services;

import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;
import android.util.Log;

import java.lang.ref.WeakReference;

import www.seven.com.server.Request;
import www.seven.com.server.Response;

/**
 * @author Seven in 2017-01-07
 */

public class NetworkTask extends AsyncTask<Request, Integer, Response> {

    private WeakReference<Handler> mWeakRef;

    public NetworkTask(Handler receiver) {
        mWeakRef = new WeakReference<Handler>(receiver);
    }

    @Override
    protected Response doInBackground(Request... requests) {
        Log.d("SevenThread", "[NetworkTask] Current Thread " + Thread.currentThread().getId());
        Response response = null;
        if (requests[0].getRequestId() % 3 == 0) {
            // 失敗的情況
            postFailure(requests[0].getRequestId(), requests[0].getUrl() + "'s response Fail !!!!");

        } else {
            // 成功的情況
            response = new Response(requests[0], 200, requests[0].getUrl() + "'s response");
        }
        return response;
    }

    @Override
    protected void onPostExecute(Response response) {
        if (response != null) {
            postSuccess(response);
        }
    }

    private void postSuccess(Response response) {
        Handler handler = mWeakRef.get();
        if (handler != null) {
            handler.obtainMessage(NetworkService.RESPONSE_SUCCESS, response).sendToTarget();

        }
    }

    private void postFailure(int reqId, String msg) {
        Handler handler = mWeakRef.get();
        if (handler != null) {
            Message message = handler.obtainMessage(NetworkService.RESPONSE_FIAL);
            message.arg1 = reqId;
            message.obj = msg;
            message.sendToTarget();
        }
    }
}

該Handler來自于NetwokService，NetworkService的實(shí)現(xiàn)如下：

package www.seven.com.server.services;

import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.RemoteException;
import android.support.annotation.Nullable;
import android.util.Log;

import java.security.PublicKey;

import www.seven.com.server.IPostInterface;
import www.seven.com.server.IResponseInterface;
import www.seven.com.server.Request;
import www.seven.com.server.Response;

/**
 * @author Seven in 2017-01-07
 */

public class NetworkService extends Service {

    public static final int RESPONSE_SUCCESS = 0;
    public static final int RESPONSE_FIAL    = 1;

    private IResponseInterface mIResponseInterface;

    private NetworkResponseHandler mNetworkResponseHandler = new NetworkResponseHandler();

    private IPostInterface mPostInterface = new IPostInterface.Stub() {

        @Override
        public void setResponseInterface(IResponseInterface responseInterface) throws RemoteException {
            mIResponseInterface = responseInterface;
        }

        @Override
        public boolean post(Request request) throws RemoteException {
            Log.d("SevenThread", "[NetworkService] Current Thread " + Thread.currentThread().getId());
            new NetworkTask(mNetworkResponseHandler).execute(request);
            return true;
        }
    };
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return mPostInterface.asBinder();
    }

    private class NetworkResponseHandler extends Handler {

        @Override
        public void handleMessage(Message msg) {

            switch (msg.what) {
                case RESPONSE_SUCCESS:
                    handleSuccess((Response) msg.obj);
                    break;
                case RESPONSE_FIAL:
                    handleFailure(msg.arg1, (String) msg.obj);
                    break;
            }
        }
    }

    private void handleSuccess(Response response) {
        if (mIResponseInterface != null) {
            try {
                mIResponseInterface.onResponseSuccess(response.getRequest().getRequestId(), response);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    }

    private void handleFailure(int reqId, String msg) {
        if (mIResponseInterface != null) {
            try {
                mIResponseInterface.onResponseFailure(reqId, msg);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    }
}

NetworkService的具體工作是：接受一個(gè)Request，創(chuàng)建一個(gè)NetworkTask，執(zhí)行完畢后，返回給客戶進(jìn)程。

Client

客戶端比較簡單，就一個(gè)ClientActivity，具體實(shí)現(xiàn)如下：

package www.seven.com.aidldemo;

import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.os.RemoteException;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

import www.seven.com.server.IPostInterface;
import www.seven.com.server.IResponseInterface;
import www.seven.com.server.Request;
import www.seven.com.server.Response;
import www.seven.com.server.services.NetworkService;

public class ClientActivity extends AppCompatActivity {

    private static int REQ_CODE = 0;


    private IResponseInterface mIResponseInterface = new IResponseInterface.Stub() {

        @Override
        public void onResponseSuccess(final int requestId, final Response response) throws RemoteException {
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    mResponseSb.append("request " + requestId + " " + response.getResponseStr() + "\n");
                    mResponseTv.setText(mResponseSb.toString());
                }
            });
        }

        @Override
        public void onResponseFailure(final int requestId, final String msg) throws RemoteException {
            // aidl回調(diào)是在獨(dú)立的線程執(zhí)行,所以需要在ui線程更新
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    mResponseSb.append("request " + requestId + " " + msg + "\n");
                    mResponseTv.setText(mResponseSb.toString());
                }
            });
        }
    };

    private IPostInterface mIPostInterface;

    private StringBuilder mResponseSb = new StringBuilder();

    private TextView mResponseTv;

    private ServiceConnection mServiceConnection;


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

        mResponseTv = (TextView) findViewById(R.id.response);
    }

    public void onSend(View view) {

        int reqId = REQ_CODE++;
        Request request = new Request(reqId, "request " + reqId);

        mResponseSb.append("request " + reqId + "\n");
        mResponseTv.setText(mResponseSb.toString());

        if (mIPostInterface == null) {
            Intent service = new Intent(this, NetworkService.class);
            mServiceConnection = new ServerConnection(request);
            bindService(service, mServiceConnection, Context.BIND_AUTO_CREATE);
        } else {
            try {
                mIPostInterface.post(request);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    }

    private class ServerConnection implements ServiceConnection {

        private Request mRequest;

        public ServerConnection(Request request) {
            mRequest = request;
        }

        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            mIPostInterface = IPostInterface.Stub.asInterface(iBinder);

            try {
                mIPostInterface.setResponseInterface(mIResponseInterface);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
            try {
                mIPostInterface.post(mRequest);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            mIPostInterface = null;
            mServiceConnection = null;
        }
    }

    @Override
    protected void onDestroy() {
        unbindService(mServiceConnection);
        super.onDestroy();
    }
}

需要注意的點(diǎn)是：在第一次發(fā)送請(qǐng)求時(shí)，會(huì)先進(jìn)行服務(wù)綁定；IResponseInterface接收到消息時(shí)，需要在將更新view的操作放到ui線程中，因?yàn)閍idl的回調(diào)是在獨(dú)立非UI線程中的。

最后，需要在manifest文件中聲明NetworkService運(yùn)行在獨(dú)立的進(jìn)程中：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="www.seven.com.aidldemo">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name="www.seven.com.aidldemo.ClientActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service android:name="www.seven.com.server.services.NetworkService"
            android:process=":networking"
            />
    </application>

</manifest>
最后編輯于 ：
?著作權(quán)歸作者所有,轉(zhuǎn)載或內(nèi)容合作請(qǐng)聯(lián)系作者
【社區(qū)內(nèi)容提示】社區(qū)部分內(nèi)容疑似由AI輔助生成，瀏覽時(shí)請(qǐng)結(jié)合常識(shí)與多方信息審慎甄別。
平臺(tái)聲明：文章內(nèi)容（如有圖片或視頻亦包括在內(nèi)）由作者上傳并發(fā)布，文章內(nèi)容僅代表作者本人觀點(diǎn)，簡書系信息發(fā)布平臺(tái)，僅提供信息存儲(chǔ)服務(wù)。

相關(guān)閱讀更多精彩內(nèi)容

  • 國家電網(wǎng)公司企業(yè)標(biāo)準(zhǔn)（Q/GDW）- 面向?qū)ο蟮挠秒娦畔?shù)據(jù)交換協(xié)議 - 報(bào)批稿：20170802 前言： 排版 ...
    庭說閱讀 12,360評(píng)論 6贊 13
  • Spring Cloud為開發(fā)人員提供了快速構(gòu)建分布式系統(tǒng)中一些常見模式的工具（例如配置管理，服務(wù)發(fā)現(xiàn)，斷路器，智...
    卡卡羅2017閱讀 136,544評(píng)論 19贊 139
  • Android跨進(jìn)程通信IPC整體內(nèi)容如下 1、Android跨進(jìn)程通信IPC之1——Linux基礎(chǔ)2、Andro...
    隔壁老李頭閱讀 10,970評(píng)論 13贊 43
  • Android 自定義View的各種姿勢(shì)1 Activity的顯示之ViewRootImpl詳解 Activity...
    passiontim閱讀 178,954評(píng)論 25贊 709
  • 和董先生分手，已經(jīng)快三個(gè)月了。每天吃飯睡覺再正常不過的生活。這場(chǎng)失戀里，沒有大醉沒有吵和鬧，甚至安穩(wěn)的不像丟了戀愛...
    小瘋子azj閱讀 361評(píng)論 5贊 2

友情鏈接更多精彩內(nèi)容