OKhttp攔截器實現(xiàn)實踐環(huán)節(jié)源碼解析

更新時間：2023年01月05日 11:35:46 作者：itbird01

這篇文章主要為大家介紹了OKhttp攔截器實現(xiàn)實踐環(huán)節(jié)源碼解析，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進步，早日升職加薪

正文

本節(jié)我們開始自我實現(xiàn)我們自己okhttp框架中的每個攔截器。

先簡單回顧一下各個攔截器的作用：

RetryAndFollowUpInterceptor：重試攔截器

處理重試的一個攔截器，會去處理一些異常，根據(jù)底層返回的響應數(shù)據(jù)，先進行一些特殊狀態(tài)碼的判斷，例如：如果底層返回307，則根據(jù)服務端返回的最新location，重新構建新的請求，交由底層攔截器，重新發(fā)起請求。如果底層返回路由異常、某些IO異常，則會continue，重新發(fā)起請求。

BridgeInterceptor：基礎的攔截器

給我們平常發(fā)起的請求，添加通用和請求首部信息，做一個簡單的處理，設置一些通用的請求頭，Cookie、Connection、Content-Type、Content-Length，做一些返回的處理，如果返回的數(shù)據(jù)被壓縮了，采用 ZipSource，保存Cookie。

CacheInterceptor：緩存攔截器

緩存存儲策略、緩存過期策略、緩存對比策略的具體實現(xiàn)。

ConnectInterceptor：連接的攔截器

ConnectInterceptor負責連接復用、建立socket連接，okio與socket輸入輸出流綁定。

CallServerInterceptor：具體與服務器通信，給服務器寫數(shù)據(jù)和讀取數(shù)據(jù)；

攔截器的自我實現(xiàn)

好了，接下來，把我們之前寫的框架的代碼，重新梳理一下，新增一下幾個攔截器。 RealCall.java

package com.itbird.okhttpstudy.okhttp;
import android.util.Log;
import com.itbird.okhttpstudy.interceptor.BridgeInterceptor;
import com.itbird.okhttpstudy.interceptor.CacheInterceptor;
import com.itbird.okhttpstudy.interceptor.CallServerInterceptor;
import com.itbird.okhttpstudy.interceptor.ConnectInterceptor;
import com.itbird.okhttpstudy.interceptor.Interceptor;
import com.itbird.okhttpstudy.interceptor.RetryAndFollowUpInterceptor;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
 * Created by itbird on 2022/11/21
 */
public class RealCall implements Call {
    private Request request;
    private OkhttpClient okhttpClient;
    public RealCall(Request request, OkhttpClient okhttpClient) {
        this.request = request;
        this.okhttpClient = okhttpClient;
    }
    @Override
    public void enqueue(Callback callback) {
        okhttpClient.dispatcher().enqueue(new AsyncCall(callback));
    }
    @Override
    public Response execute() {
        return getResponseWithInterceptorChain();
    }
    @Override
    public Request request() {
        return request;
    }
    private Response getResponseWithInterceptorChain() {
        List<Interceptor> interceptors = new ArrayList<Interceptor>();
        interceptors.add(new BridgeInterceptor());// 基礎
        interceptors.add(new CacheInterceptor());// 緩存
        interceptors.add(new ConnectInterceptor());// 建立連接
        interceptors.add(new CallServerInterceptor());// 寫數(shù)據(jù)
        interceptors.add(new RetryAndFollowUpInterceptor());// 重試
        Interceptor.Chain chain = new RealInterceptorChain(this, interceptors, request);
        try {
            return chain.proceed(request);
        } catch (IOException e) {
            //處理過程被中斷時，通過錯誤碼返回
            return null;
        }
    }
    class AsyncCall extends NamedRunnable {
        private Callback callback;
        public AsyncCall(Callback callback) {
            this.callback = callback;
        }
        @Override
        public void execute() {
            Log.d(Constants.TAG, "AsyncCall execute");
            //這里有問題的
            Response response = getResponseWithInterceptorChain();
            if (callback != null) {
                try {
                    callback.onResponse(RealCall.this, response);
                } catch (IOException e) {
                }
            }
        }
    }
}

接下來還是老辦法，按照AS提示，新建這些類。

RetryAndFollowUpInterceptor

package com.itbird.okhttpstudy.interceptor;
import android.util.Log;
import com.itbird.okhttpstudy.okhttp.Constants;
import com.itbird.okhttpstudy.okhttp.Request;
import com.itbird.okhttpstudy.okhttp.Response;
import java.io.IOException;
/**
 * Created by itbird on 2022/11/24
 */
public class RetryAndFollowUpInterceptor implements Interceptor {
    @Override
    public Response intercept(Chain chain) throws IOException {
        Log.d(Constants.TAG, "RetryAndFollowUpInterceptor");
        Request request = chain.request();
        //okhttp表現(xiàn)為，此處，去根據(jù)底層拋出的異常，決定是否為關鍵錯誤異常，如果不是，則while true循環(huán)，去執(zhí)行重試請求
        return chain.proceed(request);
    }
}

BridgeInterceptor

package com.itbird.okhttpstudy.interceptor;
import android.util.Log;
import com.itbird.okhttpstudy.okhttp.Constants;
import com.itbird.okhttpstudy.okhttp.Request;
import com.itbird.okhttpstudy.okhttp.RequsetBody;
import com.itbird.okhttpstudy.okhttp.Response;
import java.io.IOException;
/**
 * Created by itbird on 2022/11/24
 */
public class BridgeInterceptor implements Interceptor {
    public BridgeInterceptor() {
    }
    @Override
    public Response intercept(Chain chain) throws IOException {
        Log.d(Constants.TAG, "BridgeInterceptor");
        Request request = chain.request();
        // 添加一些請求頭
//        request.addParam("Connection", "keep-alive");
        // 做一些其他處理
        if (request.requsetBody() != null) {
            RequsetBody requestBody = request.requsetBody();
            request.addParam("Content-Type", requestBody.getContentType());
            request.addParam("Content-Length", Long.toString(requestBody.getContentLength()));
        }
        //GZIP數(shù)據(jù)流轉換
        return chain.proceed(request);
    }
}

CacheInterceptor

package com.itbird.okhttpstudy.interceptor;
import android.util.Log;
import com.itbird.okhttpstudy.okhttp.CacheControl;
import com.itbird.okhttpstudy.okhttp.Constants;
import com.itbird.okhttpstudy.okhttp.Request;
import com.itbird.okhttpstudy.okhttp.Response;
import java.io.IOException;
/**
 * Created by itbird on 2022/11/24
 */
public class CacheInterceptor implements Interceptor {
    public CacheInterceptor() {
    }
    @Override
    public Response intercept(Chain chain) throws IOException {
        Log.d(Constants.TAG, "CacheInterceptor");
        Request request = chain.request();
        if (request.cache() == CacheControl.FORCE_CACHE) {
            //本地緩存有沒有，緩存過期了沒有，緩存對比服務器返回307
        }
        return chain.proceed(request);
    }
}

ConnectInterceptor

package com.itbird.okhttpstudy.interceptor;
import android.util.Log;
import com.itbird.okhttpstudy.okhttp.Constants;
import com.itbird.okhttpstudy.okhttp.Request;
import com.itbird.okhttpstudy.okhttp.Response;
import java.io.IOException;
/**
 * Created by itbird on 2022/11/24
 */
public class ConnectInterceptor implements Interceptor {
    public ConnectInterceptor() {
    }
    @Override
    public Response intercept(Chain chain) throws IOException {
        Log.d(Constants.TAG, "ConnectInterceptor");
        Request request = chain.request();
        //表現(xiàn)為okhttp的話，這里就是socket簡歷連接，并且將socket輸入輸出流與okio綁定在一起
        return chain.proceed(request);
    }
}

CallServerInterceptor

package com.itbird.okhttpstudy.interceptor;
import android.util.Log;
import com.itbird.okhttpstudy.okhttp.Constants;
import com.itbird.okhttpstudy.okhttp.Request;
import com.itbird.okhttpstudy.okhttp.Response;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
/**
 * Created by itbird on 2022/11/24
 */
public class CallServerInterceptor implements Interceptor {
    public CallServerInterceptor() {
    }
    @Override
    public Response intercept(Chain chain) throws IOException {
        Log.d(Constants.TAG, "CallServerInterceptor");
        Request request = chain.request();
        try {
            //獲取連接請求
            URL url = new URL(request.url());
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            //設置連接超時
            httpURLConnection.setConnectTimeout(3000);
            //設置方法
            httpURLConnection.setRequestMethod(request.method());
            if (request.requsetBody() != null) {
                httpURLConnection.setRequestProperty("Content-Type", request.requsetBody().getContentType());
                httpURLConnection.setRequestProperty("Content-Length", String.valueOf(request.requsetBody().getContentLength()));
                Log.d(Constants.TAG, httpURLConnection.getRequestProperty("Content-Length"));
                Log.d(Constants.TAG, httpURLConnection.getRequestProperty("Content-Type"));
            }
            //開始連接
            httpURLConnection.connect();
            //插入，如果requsetbody不為空，則繼續(xù)寫入內容
            if (request.requsetBody() != null) {
                request.requsetBody().writeBodyData(httpURLConnection.getOutputStream());
            }
            //判斷返回的狀態(tài)碼
            if (httpURLConnection.getResponseCode() == 200) {
                //獲取返回的數(shù)據(jù)
                InputStream inputStream = httpURLConnection.getInputStream();
                //將返回的數(shù)據(jù)，封裝為response
                Response response = new Response(inputStream);
                return response;
            }
        } catch (MalformedURLException e) {
            throw e;
        } catch (IOException e) {
            throw e;
        }
        return null;
    }
}