OkHttp源码学习和应用
OkHttp是由Square创建的一个开源项目，旨在成为一个高效的HTTP和HTTP/2客户端。它可以有效地执行HTTP请求，加快请求的负载和节省带宽。它提供了几个强大的功能，如同一主机的所有HTTP/2请求共享一个套接字；HTTP/2不可用时，连接池减少请求时延；Transparent GZIP减少下载大小；响应缓存可以完全避免重复网络请求。此外，OkHttp有一个很好的机制来管理常见的连接问题。现在，它也支持WebSocket。
拦截器是OkHttp中提供一种强大机制，它可以实现网络监听、请求以及响应重写、请求失败重试等功能。恰当地使用拦截器非常重要，笔者目前正在开发维护的项目中的诸多功能都与OkHttp的拦截器相关，比如App本地缓存，移动流量免流，容灾，域名劫持等，同时，OkHttp拦截器的设计思路也非常值得开发者学习，比如开屏广告，播放器播放条件判断等。因此，我决定写一篇OkHttp拦截器的文章，通过源码分析介绍几个tips。
拦截器设计--一语道破
OkHttp的多个拦截器可以链接起来，形成一个链条。拦截器会按照在链条上的顺序依次执行。 拦截器在执行时，可以先对请求的 Request 对象进行修改；在得到响应的 Response 对象之后，可以进行修改之后再返回。见官方介绍 拦截器拦截顺序图 ，问题来了，请问：为何这个顺序是这样的？
import java.io.IOException;
//拦截器接口
public interface Interceptor {
MyResponse intercept(Chain chain) throws IOException;
interface Chain {
MyRequest request();
MyResponse proceed(MyRequest request) throws IOException;
}
}
复制代码
/**
* Created by guokun on 2018/12/4.
* Description: 模仿OkHttp Interceptor 责任链设计模式
*/
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public final class MyInterceptorChain implements Interceptor.Chain {
private final List<Interceptor> interceptors;
private final MyRequest myRequest;
// private int calls;
private int index;
public MyInterceptorChain(List<Interceptor> interceptors, int index, MyRequest myRequest) {
this.interceptors = interceptors;
this.index = index;
this.myRequest = myRequest;
}
public static void main(String[] args) {
OneInterceptor oneInterceptor = new OneInterceptor("one_Request", "one_response");
TwoInterceptor twoInterceptor = new TwoInterceptor("two_request", "two_response");
ThreeInterceptor threeInterceptor = new ThreeInterceptor("three_request", " three_response");
final List<Interceptor> interceptors = new ArrayList<>();
interceptors.add(oneInterceptor);
interceptors.add(twoInterceptor);
interceptors.add(threeInterceptor);
final MyRequest mainRequest = new MyRequest("main ");
MyInterceptorChain myInterceptorChain = new MyInterceptorChain(interceptors, 0, mainRequest);
try {
System.out.println(myInterceptorChain.proceed(mainRequest).getResponseDiscription());
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public MyRequest request() {
return myRequest;
}
@Override
public MyResponse proceed(MyRequest request) throws IOException {
if (index >= interceptors.size()) throw new AssertionError();
// calls++;
//递归调用每个拦截器
MyInterceptorChain next = new MyInterceptorChain(interceptors, index + 1, request);
Interceptor interceptor = interceptors.get(index);
MyResponse response = interceptor.intercept(next);
return response;
}
}
复制代码
public class MyRequest {
private String requestdiscription;
public MyRequest() {
System.out.println("request construct enter");
}
public MyRequest(String discription) {
this.requestdiscription = discription;
}
public String getRequestdiscription() {
return requestdiscription;
}
public void setRequestdiscription(String requestdis) {
this.requestdiscription = this.requestdiscription + " " + requestdis;
}
}
复制代码
public class MyResponse {
private String responseDiscription;
public MyResponse() {
System.out.println("response construct enter");
}
public MyResponse(String discription) {
this.responseDiscription = discription;
}
public String getResponseDiscription() {
return responseDiscription;
}
public void setResponseDiscription(String responseDis) {
this.responseDiscription = this.responseDiscription + " " + responseDis;
}
}
复制代码
import java.io.IOException;
public final class OneInterceptor implements Interceptor {
private String oneRequest;
private String oneResponse;
public OneInterceptor(String oneRequest, String oneResponse) {
this.oneRequest = oneRequest;
this.oneResponse = oneResponse;
}
@Override
public MyResponse intercept(Chain chain) throws IOException {
MyRequest myRequest = chain.request();
myRequest.setRequestdiscription(oneRequest);
System.out.println("one interceptor --------------request====" + myRequest.getRequestdiscription());
MyResponse myResponse = chain.proceed(myRequest);
myResponse.setResponseDiscription(oneResponse);
System.out.println("one interceptor -----------------response=======" + myResponse.getResponseDiscription());
return myResponse;
}
}
复制代码
import java.io.IOException;
public final class TwoInterceptor implements Interceptor {
private String twoRequest;
private String twoResponse;
public TwoInterceptor(String oneRequest, String oneResponse) {
this.twoRequest = oneRequest;
this.twoResponse = oneResponse;
}
@Override
public MyResponse intercept(Chain chain) throws IOException {
MyRequest myRequest = chain.request();
myRequest.setRequestdiscription(twoRequest);
System.out.println("two interceptor-----------request=======" + myRequest.getRequestdiscription());
MyResponse myResponse = chain.proceed(myRequest);
// MyResponse myResponse = testFor(null, chain);
myResponse.setResponseDiscription(twoResponse);
System.out.println("two interceptor---------response===" + myResponse.getResponseDiscription());
return myResponse;
}
private MyResponse testFor(MyResponse myResponse, Chain chain) throws IOException {
MyRequest myRequest = chain.request();
MyResponse response = null;
for (int i = 0; i < 2; i++) {
MyRequest myRequest1 = new MyRequest(myRequest + "----" + i + " " + myRequest.getRequestdiscription());
response = chain.proceed(myRequest1);
}
return response;
}
}
复制代码
import java.io.IOException;
public final class ThreeInterceptor implements Interceptor {
private String threeRequest;
private String threeResponse;
public ThreeInterceptor(String oneRequest, String oneResponse) {
this.threeRequest = oneRequest;
this.threeResponse = oneResponse;
}
@Override
public MyResponse intercept(Chain chain) throws IOException {
MyRequest myRequest = chain.request();
myRequest.setRequestdiscription(threeRequest);
System.out.println("three interceptor ------------request=====" + myRequest.getRequestdiscription());
MyResponse myResponse = new MyResponse("threeResponse ");
System.out.println("three interceptor ------------response ======" + myResponse.getResponseDiscription());
return myResponse;
}
}
复制代码
one interceptor --------------request====main one_Request two interceptor-----------request=======main one_Request two_request three interceptor ------------request=====main one_Request two_request three_request three interceptor ------------response ======threeResponse two interceptor---------response===threeResponse two_response one interceptor -----------------response=======threeResponse two_response one_response threeResponse two_response one_response 复制代码
理解上述代码调用逻辑就不难理解OkHttp的拦截器的调用逻辑，源码RealInterceptorChain对应MyInterceptorChain
package okhttp3.internal.http;
import java.io.IOException;
import java.util.List;
import okhttp3.Connection;
import okhttp3.HttpUrl;
import okhttp3.Interceptor;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.internal.connection.StreamAllocation;
/**
* A concrete interceptor chain that carries the entire interceptor chain: all application
* interceptors, the OkHttp core, all network interceptors, and finally the network caller.
*/
public final class RealInterceptorChain implements Interceptor.Chain {
private final List<Interceptor> interceptors;
private final StreamAllocation streamAllocation;
private final HttpCodec httpCodec;
private final Connection connection;
private final int index;
private final Request request;
private int calls;
public RealInterceptorChain(List<Interceptor> interceptors, StreamAllocation streamAllocation,
HttpCodec httpCodec, Connection connection, int index, Request request) {
this.interceptors = interceptors;
this.connection = connection;
this.streamAllocation = streamAllocation;
this.httpCodec = httpCodec;
this.index = index;
this.request = request;
}
@Override public Connection connection() {
return connection;
}
public StreamAllocation streamAllocation() {
return streamAllocation;
}
public HttpCodec httpStream() {
return httpCodec;
}
@Override public Request request() {
return request;
}
//关键方法
@Override public Response proceed(Request request) throws IOException {
return proceed(request, streamAllocation, httpCodec, connection);
}
//关键方法
public Response proceed(Request request, StreamAllocation streamAllocation, HttpCodec httpCodec,
Connection connection) throws IOException {
if (index >= interceptors.size()) throw new AssertionError();
calls++;
// If we already have a stream, confirm that the incoming request will use it.
if (this.httpCodec != null && !sameConnection(request.url())) {
throw new IllegalStateException("network interceptor " + interceptors.get(index - 1)
+ " must retain the same host and port");
}
// If we already have a stream, confirm that this is the only call to chain.proceed().
if (this.httpCodec != null && calls > 1) {
throw new IllegalStateException("network interceptor " + interceptors.get(index - 1)
+ " must call proceed() exactly once");
}
//关键代码
// Call the next interceptor in the chain.
RealInterceptorChain next = new RealInterceptorChain(
interceptors, streamAllocation, httpCodec, connection, index + 1, request);
Interceptor interceptor = interceptors.get(index);
Response response = interceptor.intercept(next);
// Confirm that the next interceptor made its required call to chain.proceed().
if (httpCodec != null && index + 1 < interceptors.size() && next.calls != 1) {
throw new IllegalStateException("network interceptor " + interceptor
+ " must call proceed() exactly once");
}
// Confirm that the intercepted response isn't null.
if (response == null) {
throw new NullPointerException("interceptor " + interceptor + " returned null");
}
return response;
}
private boolean sameConnection(HttpUrl url) {
return url.host().equals(connection.route().address().url().host())
&& url.port() == connection.route().address().url().port();
}
}
复制代码
应用拦截器VS网络拦截器
OkHttp有两类拦截器--应用拦截器和网络拦截器，两者有很大的区别。
import static okhttp3.internal.platform.Platform.INFO;
final class RealCall implements Call {
......
Response getResponseWithInterceptorChain() throws IOException {
// Build a full stack of interceptors.
List<Interceptor> interceptors = new ArrayList<>();
//应用拦截器
interceptors.addAll(client.interceptors());
interceptors.add(retryAndFollowUpInterceptor);
interceptors.add(new BridgeInterceptor(client.cookieJar()));
interceptors.add(new CacheInterceptor(client.internalCache()));
interceptors.add(new ConnectInterceptor(client));
if (!forWebSocket) {
//网络拦截器
interceptors.addAll(client.networkInterceptors());
}
interceptors.add(new CallServerInterceptor(forWebSocket));
Interceptor.Chain chain = new RealInterceptorChain(
interceptors, null, null, null, 0, originalRequest);
return chain.proceed(originalRequest);
}
}
复制代码
官网上有一段两者区别的解释和示例，笔者能力有限暂无法从代码给出相关的答案。
Application interceptors
- 无法操作中间的响应结果，比如当URL重定向发生以及请求重试等，只能操作客户端主动第一次请求以及最终的响应结果。
- 在任何情况下只会调用一次，即使这个响应来自于缓存。
- 可以监听观察这个请求的最原始未经改变的意图（请求头，请求体等），无法操作OkHttp为我们自动添加的额外的请求头，比如If-None-Match。
- 允许short-circuit (短路)并且允许不去调用Chain.proceed()。（编者注：这句话的意思是Chain.proceed()不需要一定要调用去服务器请求，但是必须还是需要返回Respond实例。那么实例从哪里来？答案是缓存。如果本地有缓存，可以从本地缓存中获取响应实例返回给客户端。这就是short-circuit (短路)的意思。。囧）
- 允许请求失败重试以及多次调用Chain.proceed()。
Network Interceptors
- 允许操作中间响应，比如当请求操作发生重定向或者重试等。
- 不允许调用缓存来short-circuit (短路)这个请求。（编者注：意思就是说不能从缓存池中获取缓存对象返回给客户端，必须通过请求服务的方式获取响应，也就是Chain.proceed()）
- 可以监听数据的传输
- 允许Connection对象装载这个请求对象。（编者注：Connection是通过Chain.proceed()获取的非空对象）
APP本地缓存
在无网络的情况下打开App，App会加载本地缓存的数据；那么问题来了，既然缓存了本地数据，我们如何去缓存数据呢？
很简单，网络数据请求成功后立即保存一份在本地。问题来了，保存数据的逻辑写在那里？
- 加在每个请求方法里；
- 加在http请求里；
方法2显然是更好的方式，既简单又利于扩展和维护。OkHttp拦截器加一个缓存Interceptor即可。
import android.text.TextUtils;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import okhttp3.Headers;
import okhttp3.Interceptor;
import okhttp3.MediaType;
import okhttp3.Protocol;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
import tingshu.bubei.netwrapper.CacheProcessor;
import static tingshu.bubei.netwrapper.CacheStrategy.BEFORE_NET_CACHE;
import static tingshu.bubei.netwrapper.CacheStrategy.IF_NET_FAIL_CACHE;
import static tingshu.bubei.netwrapper.CacheStrategy.IF_NET_SUCCEED_FORCE_CACHE;
import static tingshu.bubei.netwrapper.CacheStrategy.IF_NET_SUCCEED_RETURN_CACHE;
import static tingshu.bubei.netwrapper.CacheStrategy.SAVE_NET_CACHE;
public class CacheInterceptor implements Interceptor {
public static final String FORCE_CACHE_WITHOUT_NO_NET_DATA = "force_cache_without_no_net_data";
private int cacheStrategy;
private CacheProcessor cacheProcessor;
public CacheInterceptor(int strategy, CacheProcessor cacheProcessor) {
this.cacheStrategy |= strategy;
this.cacheProcessor = cacheProcessor;
if(cacheProcessor==null){
throw new RuntimeException("cacheProcessor not be null");
}
}
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Response response;
String cache = null;
if((cacheStrategy&BEFORE_NET_CACHE) == BEFORE_NET_CACHE){//预先读取缓存
cache = cacheProcessor.findCache(false);
}
if(!TextUtils.isEmpty(cache)){//读取缓存成功
ResponseBody responseBody = ResponseBody.create(MediaType.parse("application/json; charset=utf-8"), cache);
response = new Response.Builder()
.message(" ")
.request(request)
.code(200)
.protocol(Protocol.HTTP_1_1)
.body(responseBody)
.build();
}else{//缓存没有,读取网络数据
ResponseBody body = null;
IOException ioException = null;
try {
response = chain.proceed(request);
body = response.newBuilder().build().body();
} catch (IOException exception) {
response = null;
ioException = exception;
}
if(body!=null&&response.code()==200){//访问网络成功
MediaType mediaType = body.contentType();
String json = null;
try{
json = response.body().string();
}catch(IllegalStateException e){
e.printStackTrace();
}
if(!TextUtils.isEmpty(json) && !"".equals(json) &&((cacheStrategy&SAVE_NET_CACHE)==SAVE_NET_CACHE)){//网络读取成功,并且需要存缓存
try {
JSONObject jsonObject = new JSONObject(json);
int status = jsonObject.optInt("status");
if(status == 0){
cacheProcessor.saveCache(json);
}
} catch (JSONException e) {
e.printStackTrace();
}
//cacheProcessor.saveCache(json);
if((cacheStrategy&IF_NET_SUCCEED_RETURN_CACHE) == IF_NET_SUCCEED_RETURN_CACHE){//请求成功还是使用缓存中的数据
json = cacheProcessor.findCache(false);
} else if ((cacheStrategy&IF_NET_SUCCEED_FORCE_CACHE) == IF_NET_SUCCEED_FORCE_CACHE) {//请求网络成功强制读缓存
json = cacheProcessor.findCache(true);
}
}else if(TextUtils.isEmpty(json)&&((cacheStrategy&IF_NET_FAIL_CACHE)==IF_NET_FAIL_CACHE)){//网络读取失败,并且需要强制使用缓存
json = cacheProcessor.findCache(true);
}
if(json==null){
json = "";
}
body = ResponseBody.create(mediaType, json);
Headers headers = response.headers().newBuilder().build();
response = response.newBuilder().headers(headers).body(body).build();
}else if((cacheStrategy&IF_NET_FAIL_CACHE)==IF_NET_FAIL_CACHE){//网络访问不成功,并且需要强制读取缓存
cache = cacheProcessor.findCache(true);
if(!TextUtils.isEmpty(cache)){
ResponseBody responseBody = ResponseBody.create(MediaType.parse("application/json; charset=utf-8"), cache);
response = new Response.Builder()
.message(" ")
.request(request)
.code(200)
.protocol(Protocol.HTTP_1_1)
.body(responseBody)
.addHeader(FORCE_CACHE_WITHOUT_NO_NET_DATA, "true")
.build();
}
}
if (response == null) {
if (ioException == null) {
throw new IOException("访问服务器失败,页没有获取到缓存");
} else {
throw ioException;
}
}
}
return response;
}
}
复制代码
缓存处理器：获取数据和保存数据
//缓存处理器接口
public interface CacheProcessor {
//获取缓存数据
String findCache(boolean forceFind);
//保存缓存数据
void saveCache(String json);
}
复制代码
JsonCache缓存处理器
public class JsonCacheProcessor implements CacheProcessor {
public static int DEFAULT_CACHE_TIME = 24;//默认缓存时长是24小时
private String key;
private float cacheHour;
public JsonCacheProcessor(String key) {
this.key = key;
this.cacheHour = DEFAULT_CACHE_TIME;
}
public JsonCacheProcessor(String key, float cacheHour) {
this.key = key;
this.cacheHour = cacheHour;
}
@Override
public String findCache(boolean forceFind) {
MiniDataCache miniDataCache = LocalDataBaseHelper.getInstance().queryMiniCache(key);
if (miniDataCache == null) return null;
long version = Utils.getCurrentHourVersion(cacheHour);
if (forceFind || miniDataCache.getVersion() == version) {
return miniDataCache.getJsonData();
}
return null;
}
@Override
public void saveCache(String json) {
LocalDataBaseHelper.getInstance().insertOrReplaceMiniCache(new MiniDataCache(key, json, Utils.getCurrentHourVersion(cacheHour)));
}
}
复制代码
免流服务--OkHttpClient配置
- 代理请求：设置代理服务器，http请求添加头部信息。
return okHttpClient.newBuilder()
.proxy(new Proxy(Proxy.Type.HTTP, InetSocketAddress.createUnresolved(/*"101.95.47.98"*/teleHttpHostName, TingshuTypeCast.intParseInt(teleHttpPort, TELEHTTPPORT_DEFAULT))))
// .addInterceptor(new RetryInterceptor())
.addInterceptor(new Interceptor() {
@Override
public Response intercept(Chain chain) throws IOException {
final String timestamp = String.valueOf(System.currentTimeMillis() / 1000);
final String token = MD5(spid + spkey + chain.request().url().host() + timestamp + telephone);
/* Log.i("hgk", " tele http----------------teleHttpHostName ===" + teleHttpHostName +
"------host =====" + chain.request().url().host() +
"------token = " + token);*/
Request newRequest = chain.request().newBuilder()
.addHeader("spid", spid)
.addHeader("x-up-calling-line-id", telephone)
.addHeader("timestamp", timestamp)
.addHeader("token", token)
.build();
Log.d(DEBUG_TEL_TAG, "telecom free traffic service has open (get method), http url ==" + newRequest.url().toString());
Response response = chain.proceed(newRequest);
if (response.code() != 200) {
Log.d(DEBUG_TEL_TAG, "Error code! telecom free traffic service has open (get method), http url response code ==" + response.code());
}
return response;
}
}).build();
复制代码
- 代理鉴权
final String timestamp = String.valueOf(System.currentTimeMillis() / 1000);
String url = Uri.parse(uri).getHost();
final String token = MD5(spid + spkey + url + timestamp + telephone);
final StringBuilder authenticatorStr = new StringBuilder("SPID=" + spid + "&");
authenticatorStr.append("URL=" + url + "&");
authenticatorStr.append("UID=" + telephone + "&");
authenticatorStr.append("TIMESTAMP=" + timestamp + "&"); //免流时长有限制
authenticatorStr.append("TOKEN=" + token);
String stringrs = authenticatorStr.toString();
// Log.i("hgk", " tele https-------------------authenticatorStr ==" + stringrs);
final String str = Base64.encodeToString(stringrs.getBytes(), Base64.NO_WRAP); //参数很重要，不要换成其它。试出来的！
Log.d(DEBUG_TEL_TAG, "telecom free traffic service has open (get method), https url ==" + uri);
Authenticator authenticator = new Authenticator() {
@Nullable
@Override
public Request authenticate(Route route, Response response) throws IOException {
return response.request().newBuilder()
.header("Proxy-Authorization", str)
.build();
}
};
return okHttpClient.newBuilder()
.proxy(new Proxy(Proxy.Type.HTTP, InetSocketAddress.createUnresolved(teleHttpsHostName, TingshuTypeCast.intParseInt(teleHttpsPort, TELEHTTPPORT_DEFAULT))))
.proxyAuthenticator(authenticator)
.addInterceptor(new Interceptor() {
@Override
public Response intercept(Chain chain) throws IOException {
Response response = chain.proceed(chain.request());
if (response.code() != 200) {
Log.d(DEBUG_TEL_TAG, "Error code! telecom free traffic service has open (init method), https response code ==" + response.code()
+ " url ===" + response.request().url());
}
return response;
}
})
.build();
复制代码
-替换请求： http://:/?xyz=:
参考文档
OkHttp3-拦截器（Interceptor） Chain of Responsibility Design Pattern OkHttp使用进阶 译自OkHttp Github官方教程 OkHttp3源码分析之拦截器Interceptor 深入理解OkHttp源码及设计思想
正文到此结束
- 本文标签： 开源项目 App 参数 主机 Service equals tab description IDE 域名 list core 处理器 ArrayList 递归 authenticate find 数据 设计模式 value client Authorization token tag 源码 Full Stack key build message bug stream 服务器 js 开发者 代码 json Connection 下载 id retry web https UI GitHub 实例 开源 文章 IO 缓存 zip git 配置 HTTP/2 parse final ACE cache Proxy java struct cat 管理 Android 开发 http ORM 连接池 ip 广告
- 版权声明： 本文为互联网转载文章，出处已在文章中说明(部分除外)。如果侵权，请联系本站长删除，谢谢。
- 本文海报： 生成海报一 生成海报二
热门推荐
相关文章
近期评论
-
文章和留言都翻到11页了 没有OOM
-
-
朋友，翻页到11页，及以后，会出现OOM，无法访问
-
-
搞个gitee的项目
-
-
版本号是多少，你可以下载哪个代码仓库，jdk选1.8 直接跑就行
-
-
-
Loading...
![[HBLOG]公众号](https://www.liuhaihua.cn/img/qrcode_gzh.jpg)
