tomcat websocket类型转换异常：org

2401_85124233

于 2024-06-17 01:49:27 发布

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文章标签： tomcat websocket java

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at org.apache.coyote.http11.AbstractHttp11Processor.action(AbstractHttp11Processor.java:842)

at org.apache.coyote.Request.action(Request.java:344)

at org.apache.catalina.connector.Request.doUpgrade(Request.java:2813)

at org.apache.catalina.connector.RequestFacade.doUpgrade(RequestFacade.java:1103)

at org.apache.catalina.websocket.WebSocketServlet.doGet(WebSocketServlet.java:131)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)

at org.apache.coyote.AbstractProtocol A b s t r a c t C o n n e c t i o n H a n d l e r . p r o c e s s ( A b s t r a c t P r o t o c o l . j a v a : 585 ) a t o r g . a p a c h e . t o m c a t . u t i l . n e t . N i o E n d p o i n t AbstractConnectionHandler.process(AbstractProtocol.java:585) at org.apache.tomcat.util.net.NioEndpoint AbstractConnectionHandler.process(AbstractProtocol.java:585)atorg.apache.tomcat.util.net.NioEndpointSocketProcessor.run(NioEndpoint.java:1653)

at java.util.concurrent.ThreadPoolExecutor W o r k e r . r u n T a s k ( T h r e a d P o o l E x e c u t o r . j a v a : 886 ) a t j a v a . u t i l . c o n c u r r e n t . T h r e a d P o o l E x e c u t o r Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor Worker.runTask(ThreadPoolExecutor.java:886)atjava.util.concurrent.ThreadPoolExecutorWorker.run(ThreadPoolExecutor.java:908)

at java.lang.Thread.run(Thread.java:662)

org.apache.coyote.Request无法转换为org.apache.coyote.http11.upgrade.UpgradeInbound。

这个异常时有时无，出现的时候也不会影响系统的正常运行。

问题定位

=======================================================================

首先从异常堆栈定位出现异常的源码位置。

at org.apache.coyote.http11.AbstractHttp11Processor.action(AbstractHttp11Processor.java:842)

at org.apache.coyote.Request.action(Request.java:344)

at org.apache.catalina.connector.Request.doUpgrade(Request.java:2813)

at org.apache.catalina.connector.RequestFacade.doUpgrade(RequestFacade.java:1103)

at org.apache.catalina.websocket.WebSocketServlet.doGet(WebSocketServlet.java:131)

1.org.apache.coyote.http11.AbstractHttp11Processor.action(AbstractHttp11Processor.java:842) ,找到源码AbstractHttp11Processor.action842行，this.upgradeInbound = ((UpgradeInbound)param);，param转为UpgradeInbound出现类型不匹配。在这里插入图片描述

2.这时看看哪里调用了AbstractHttp11Processor.action。继续看异常堆栈org.apache.coyote.Request.action(Request.java:344)，找到org.apache.coyote.Request类第344行：

在这里插入图片描述

343行代码会判断param是否为null，param=null，调用this.hook.action(actionCode, this);第二个参数直接传了一个this，这个this就是org.apache.coyote.Request。从这里就已经看出因为参数param=null，直接把org.apache.coyote.Request本身当作param传给了hook.action()，这个hook就是org.apache.coyote.http11.AbstractHttp11Processor。（AbstractHttp11Processor继承了AbstractProcessor，AbstractProcessor实现了接口ActionHook）

3.继续深究，什么情况下org.apache.coyote.Request.action(ActionCode actionCode, Object param)的第二个参数param等于null呢?

找到org.apache.catalina.connector.Request.doUpgrade(Request.java:2813)代码位置，可以看到该方法第二个参数UpgradeInbound inbound，也就验证了org.apache.coyote.Request cannot be cast to org.apache.coyote.http11.upgrade.UpgradeInbound。

在这里插入图片描述

4.at org.apache.catalina.connector.RequestFacade.doUpgrade(RequestFacade.java:1103)

在这里插入图片描述

5.at org.apache.catalina.websocket.WebSocketServlet.doGet(WebSocketServlet.java:131)，从源码可以看到StreamInbound inbound = createWebSocketInbound(subProtocol, wrapper);，源头找到了，就是因为createWebSocketInbound这个方法创建的inbound可能等于null，然后就出现了后面类型转换的问题。

在这里插入图片描述

protected abstract StreamInbound createWebSocketInbound(String paramString, HttpServletRequest paramHttpServletRequest);

public abstract class StreamInbound

implements UpgradeInbound{…}

createWebSocketInbound是一个静态方法，使用tomcat的webSocket的功能，需要继承org.apache.catalina.websocket.WebSocketServlet，实现createWebSocketInbound，这个跟wesocket三次握手建立连接有关。查看项目代码，自行实现的createWebSocketInbound确实存在返回null的情况。

在这里插入图片描述