用 okhttp 区分连接超时和读取超时

Question

我正在使用带有 spring 的功能区的 okhttp。 我希望在连接超时而不是读取超时时重试另一个服务实例（原因很明显）。此重试将由自定义功能区重试处理程序处理。但要做到以上几点，我需要区分读取超时和连接超时。 okhttp 的行为如下：

• 读取超时：

  java.net.SocketTimeoutException: timeout
      at okio.Okio$3.newTimeoutException(Okio.java:212)
      at okio.AsyncTimeout.exit(AsyncTimeout.java:288)
      at okio.AsyncTimeout$2.read(AsyncTimeout.java:242)
      at okio.RealBufferedSource.indexOf(RealBufferedSource.java:325)
      at okio.RealBufferedSource.indexOf(RealBufferedSource.java:314)
      at okio.RealBufferedSource.readUtf8LineStrict(RealBufferedSource.java:210)
      at okhttp3.internal.http.Http1xStream.readResponse(Http1xStream.java:184)
      at okhttp3.internal.http.Http1xStream.readResponseHeaders(Http1xStream.java:125)
      at okhttp3.internal.http.HttpEngine.readNetworkResponse(HttpEngine.java:775)
      at okhttp3.internal.http.HttpEngine.access$200(HttpEngine.java:86)
      at okhttp3.internal.http.HttpEngine$NetworkInterceptorChain.proceed(HttpEngine.java:760)
      at okhttp3.internal.http.HttpEngine.readResponse(HttpEngine.java:613)
      at okhttp3.RealCall.getResponse(RealCall.java:244)
      at okhttp3.RealCall$ApplicationInterceptorChain.proceed(RealCall.java:201)
      at com.bluejeans.sample.test.OkHttpConnect$1.intercept(OkHttpConnect.java:25)
      at okhttp3.RealCall$ApplicationInterceptorChain.proceed(RealCall.java:190)
      at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:163)
      at okhttp3.RealCall.execute(RealCall.java:57)
      at com.bluejeans.sample.test.OkHttpConnect.main(OkHttpConnect.java:39)
  Caused by: java.net.SocketTimeoutException: Read timed out
      at java.net.SocketInputStream.socketRead0(Native Method)
      at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
      at java.net.SocketInputStream.read(SocketInputStream.java:170)
      at java.net.SocketInputStream.read(SocketInputStream.java:141)
      at okio.Okio$2.read(Okio.java:140)
      at okio.AsyncTimeout$2.read(AsyncTimeout.java:238)
      ... 16 more
  

• 连接超时：

   java.net.SocketTimeoutException: connect timed out
      at java.net.PlainSocketImpl.socketConnect(Native Method)
      at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
      at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
      at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
      at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
      at java.net.Socket.connect(Socket.java:589)
      at okhttp3.internal.Platform.connectSocket(Platform.java:121)
      at okhttp3.internal.io.RealConnection.connectSocket(RealConnection.java:185)
      at okhttp3.internal.io.RealConnection.buildConnection(RealConnection.java:170)
      at okhttp3.internal.io.RealConnection.connect(RealConnection.java:111)
      at okhttp3.internal.http.StreamAllocation.findConnection(StreamAllocation.java:187)
      at okhttp3.internal.http.StreamAllocation.findHealthyConnection(StreamAllocation.java:123)
      at okhttp3.internal.http.StreamAllocation.newStream(StreamAllocation.java:93)
      at okhttp3.internal.http.HttpEngine.connect(HttpEngine.java:296)
      at okhttp3.internal.http.HttpEngine.sendRequest(HttpEngine.java:248)
      at okhttp3.RealCall.getResponse(RealCall.java:243)
      at okhttp3.RealCall$ApplicationInterceptorChain.proceed(RealCall.java:201)
      at com.bluejeans.sample.test.OkHttpConnect$1.intercept(OkHttpConnect.java:25)
      at okhttp3.RealCall$ApplicationInterceptorChain.proceed(RealCall.java:190)
      at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:163)
      at okhttp3.RealCall.execute(RealCall.java:57)
      at com.bluejeans.sample.test.OkHttpConnect.main(OkHttpConnect.java:39)
  

根据异常消息做出决定似乎不是一个好主意。实现这一目标的推荐方法是什么？

Answer 1

如果您不想依赖消息，您也可以选择以下选项。但是它们都需要 JUnit 覆盖，因为 OkHttp 的开发人员将来可能会更改他们的实现。

1. 使用异常的原因来决定如何处理请求：

   try {
       ...
   } catch (SocketTimeoutException e) {
       if (e.getCause() != null && e.getCause() instanceof SocketTimeoutException) {
           // read timeout
       } else {
           // socket timeout
       }
   }
   

2. 遍历堆栈跟踪：

   try {
       ...
   } catch (SocketTimeoutException e) {
       boolean isConnectException = false;
       for (StackTraceElement elem : e.getStackTrace()) {
           if ("java.net.Socket".equals(elem.getClassName()) &&
                   "connect".equals(elem.getMethodName())) {
               isConnectException = true;
               break;
           }
       }
       ...
   }