Question

根据Servlet 3.1容器上的documentation ，ServletHttpHandlerAdapter可以注册为Servlet并可以支持nio。我需要将请求转发到如下所示的其他资源

asyncContext.getRequest().getServletContext().getRequestDispatcher("/OtherResource")
                .forward(asyncContext.getRequest(), asyncContext.getResponse());

在致电时我遇到了错误。

java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:624)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:211)
at com.nucleus.OtherServlet.doGet(OtherServlet.java:30)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:728)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:470)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:395)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:316)
at com.nucleus.AsyncRequestProcessor.run(AsyncRequestProcessor.java:55)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

当spring创建org.springframework.http.server.reactive.ServletServerHttpResponse并最初调用response.getOutputStream（）时，这是正确的，现在如何支持请求转发？

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Answer 1

借助于ServletHttpHandlerAdapter，Spring WebFlux可以部署在Servlet 3.1容器上-但这并不意味着您可以在该应用程序中使用Servlet特定的API。

首先，一旦使用了异步I / O Servlet功能，就不允许将它们与Servlet API（see this presentation about Servlet 3.1 async IO）上阻止I / O调用混合使用。

因此，一般而言，您永远不要尝试从ServerWebExchange获取特定于Servlet的对象，而应针对Spring WebFlux中这种新的HTTP基础进行编码。

There is an issue about supporting forwarding at the WebFlux level，但我不确定这最终能否解决您的问题。我不了解您遇到的问题的具体细节，但是Spring WebFlux已经支持使用阻塞I / O（see Freemarker support here）的模板引擎。

如果您要支持的模板引擎与Servlet绑定，那么您将无法获得适当的WebFlux支持，因为可以在非Servlet环境中运行Spring WebFlux应用程序。

Servlet 3.1容器中的ServletHttpHandlerAdapter spring web-flux请求转发

1 个答案: