websocket 服务使用 Nginx 反向代理后，发现会自动断开，查看日志如下
java.io.EOFException
at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1231)
at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.read(NioEndpoint.java:1141)
at org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:72)
at org.apache.tomcat.websocket.server.WsFrameServer.doOnDataAvailable(WsFrameServer.java:171)
at org.apache.tomcat.websocket.server.WsFrameServer.notifyDataAvailable(WsFrameServer.java:151)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.upgradeDispatch(WsHttpUpgradeHandler.java:148)
at org.apache.coyote.http11.upgrade.UpgradeProcessorInternal.dispatch(UpgradeProcessorInternal.java:54)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:59)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
原因：使用了 Nginx 反向代理后，超过60S没有数据传输的连接会自动断开。
解决方法有两个：
- 修改nginx配置,
proxy_read_timeout默认60s断开，修改即可，比如60分钟
proxy_pass http://itoa-server:8080/apiv2/websocket;
proxy_read_timeout 3600s;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
- 前端或者后端加个定时任务发个心跳包就好了，例如：
timer=setInterval(function() {
if (websocket.readyState == 1) {
websocket.send("心跳包检测");
} else {
//IM连接已断开
}
}, 50 * 1000);