OkHttp 源码解析---拦截器

拦截器的执行顺序是是什么？


okhttp3.RealCall#getResponseWithInterceptorChainResponse getResponseWithInterceptorChain() throws IOException {// Build a full stack of interceptors.List<Interceptor> interceptors = new ArrayList<>();interceptors.addAll(client.interceptors());interceptors.add(new RetryAndFollowUpInterceptor(client));interceptors.add(new BridgeInterceptor(client.cookieJar()));interceptors.add(new CacheInterceptor(client.internalCache()));interceptors.add(new ConnectInterceptor(client));if (!forWebSocket) {interceptors.addAll(client.networkInterceptors());}interceptors.add(new CallServerInterceptor(forWebSocket));Interceptor.Chain chain = new RealInterceptorChain(interceptors, transmitter, null, 0,originalRequest, this, client.connectTimeoutMillis(),client.readTimeoutMillis(), client.writeTimeoutMillis());boolean calledNoMoreExchanges = false;try {Response response = chain.proceed(originalRequest);if (transmitter.isCanceled()) {closeQuietly(response);throw new IOException("Canceled");}return response;} catch (IOException e) {calledNoMoreExchanges = true;throw transmitter.noMoreExchanges(e);} finally {if (!calledNoMoreExchanges) {transmitter.noMoreExchanges(null);}}}

这里有定义顺序，我们也可以从调用堆栈里面看到整个拦截器执行的顺序。

调用堆栈

"OkHttp https://www.baidu.com/...@9689" prio=5 tid=0xae nid=NA runnablejava.lang.Thread.State: RUNNABLEat okhttp3.internal.http.CallServerInterceptor.intercept(CallServerInterceptor.java:37)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:43)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117)at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:94)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117)at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:88)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117)at com.example.okhttptest.MainActivity$1.intercept(MainActivity.java:27)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117)at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:229)at okhttp3.RealCall$AsyncCall.execute(RealCall.java:172)at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)at java.lang.Thread.run(Thread.java:919)

如何拦截替换请求

        OkHttpClient okHttpClient = new OkHttpClient.Builder().addInterceptor(new Interceptor() {@Overridepublic Response intercept(Chain chain) throws IOException {Request request = chain.request().newBuilder().url("https://www.sina.com.cn/").build();return chain.proceed(request);}}).build();

如果手机没有网，那么重试拦截器会重试吗？

不会

各层拦截器的作用是什么？

在 RealCall 中会按照顺序添加如下几个默认的 Interceptor 到责任链中用来完成基本功能：

用户设置的 Interceptor
RetryAndFollowUpInterceptor：失败重试及重定向
BridgeInterceptor：处理网络 Header、Cookie、gzip 等
CacheInterceptor：管理缓存
ConnectInterceptor：连接服务器
如果是 WebSocket 请求则添加对应的 Interceptors
CallServerInterceptor：数据发送/接收

networkInterceptors 和 Interceptors 的区别是什么？

执行顺序不一样，如果遇到304 重定向，netWorkInteceptors 能够监听到，而普通的application interceptors监听不到。application interceptors 只调用一次，不会处理到304.

所有的拦截器没有使用for 循环，是怎么进行按照顺序调用的？

RealInterceptorChain 调用第一个 Interceptors 的 process 方法，第一个Interceptors 的process 方法中会调用下一个拦截器的intercept 方法，

okhttp3.internal.http.RealInterceptorChain#proceed() 注定会创建一个新的RealInterceptorChain，然后调用下一个拦截器的intercept 方法，并传入下一个chain,interceptor 处理完就调用chain 的process，chain 的 process 会获取到下一个拦截器，并传递下一次chain,就可以层层传递。

异步任务线程的名字在哪里定义的？

OkHttp https://www.baidu.com/…

public abstract class NamedRunnable implements Runnable {protected final String name;public NamedRunnable(String format, Object... args) {this.name = Util.format(format, args);}@Override public final void run() {String oldName = Thread.currentThread().getName();Thread.currentThread().setName(name);try {execute();} finally {Thread.currentThread().setName(oldName);}}protected abstract void execute();
}

一些参考：

https://zhuanlan.zhihu.com/p/104813091