Android中使用Retrofit2请求出现SocketTimeoutException的原因

问题描述 #

在Android中使用Retrofit2调用服务时，抛出**SocketTimeoutException: 连接超时**错误，请求的服务地址为 http://182.20.1.14:2020/api/MainAppExternal/UpdateFcmId。

相关代码实现：

private Retrofit retrofit(String url, boolean addLogInterceptor, int timeout) {
    return new Retrofit.Builder()
            .baseUrl(url).client(getOkHttpClient(addLogInterceptor, timeout))
            .addConverterFactory(GsonConverterFactory.create(LocalGsonBuilder.getInstance().getGson()))
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .build();
}

private OkHttpClient getOkHttpClient(boolean addLogInterceptor, int timeout) {
    OkHttpClient.Builder httpClient = new OkHttpClient.Builder()
            .connectTimeout(CONNECTION_TIMEOUT, TimeUnit.SECONDS);

    setupInterceptor(httpClient, addLogInterceptor);
    setupTimeout(httpClient, timeout);

    return httpClient.build();
}

private void setupInterceptor(OkHttpClient.Builder httpClient, boolean addLogInterceptor) {
    if (addLogInterceptor) {
        httpClient.addInterceptor(new ConnectionInterceptor());
    }
}

完整异常堆栈信息：

exception : connect timed outjava.net.SocketTimeoutException: connect timed out at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:341)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:196)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:178)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:356)
at java.net.Socket.connect(Socket.java:650)
at okhttp3.internal.platform.AndroidPlatform.connectSocket(AndroidPlatform.java:63)
at okhttp3.internal.connection.RealConnection.connectSocket(RealConnection.java:223)
at okhttp3.internal.connection.RealConnection.connect(RealConnection.java:149)
at okhttp3.internal.connection.StreamAllocation.findConnection(StreamAllocation.java:192)
at okhttp3.internal.connection.StreamAllocation.findHealthyConnection(StreamAllocation.java:121)
at okhttp3.internal.connection.StreamAllocation.newStream(StreamAllocation.java:100)
at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:42)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:93)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:120)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at com.dgpays.mpos.common.common.ConnectionInterceptor.intercept(ConnectionInterceptor.java:84)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:185)
at okhttp3.RealCall.execute(RealCall.java:69)
at retrofit2.OkHttpCall.execute(OkHttpCall.java:180)
at retrofit2.adapter.rxjava2.CallExecuteObservable.subscribeActual(CallExecuteObservable.java:41)
at io.reactivex.Observable.subscribe(Observable.java:12267)
at retrofit2.adapter.rxjava2.BodyObservable.subscribeActual(BodyObservable.java:34)
at io.reactivex.Observable.subscribe(Observable.java:12267)
at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeTask.run(ObservableSubscribeOn.java:96)
at io.reactivex.Scheduler$DisposeTask.run(Scheduler.java:578)
at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:66)
at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:57)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:272)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)

异常原因解析 #

SocketTimeoutException: connect timed out表示客户端在设定的时间内无法与目标服务器完成TCP连接建立，常见诱因分为以下几类：

1. 网络环境层面 #

• 设备当前网络信号弱（如偏远地区移动数据、Wi-Fi信号不稳定），导致TCP三次握手无法完成
• 设备处于代理网络环境，代理配置错误或代理服务器自身不可用
• 本地防火墙、路由器或运营商网络拦截了对目标IP和端口的连接请求

2. 服务器端层面 #

• 目标服务器182.20.1.14未启动，或2020端口对应的服务已崩溃
• 服务器的防火墙/安全组未开放2020端口，拒绝外部设备的连接请求
• 服务器负载过高，线程池已满，无法及时处理新的连接请求

3. 客户端配置层面 #

• 代码中CONNECTION_TIMEOUT常量设置过短，TCP连接还未完成握手就触发超时
• setupTimeout方法可能覆盖了初始设置的连接超时参数，导致实际超时时间不符合预期
• 自定义的ConnectionInterceptor可能修改了请求头、URL或拦截了连接流程，影响正常连接

排查建议 #

1. 验证网络连通性：在设备或电脑上执行ping 182.20.1.14测试能否连通服务器，用telnet 182.20.1.14 2020测试端口是否开放
2. 确认服务器状态：联系后端人员确认服务是否正常运行，2020端口是否在监听，安全组是否允许当前设备的IP访问
3. 调整超时配置：临时将CONNECTION_TIMEOUT调至30秒，观察是否还会出现超时
4. 排查自定义拦截器：暂时移除ConnectionInterceptor，测试请求是否正常，排除拦截器的影响
5. 切换网络测试：将设备切换到其他网络（如从Wi-Fi切换到移动数据），确认是否是当前网络的问题

内容的提问来源于stack exchange，提问作者ridvan