eclipse Filter web.xml 问题解决异步请求@WebServlet

2021-08-26 00:09:24

<filter>

   <filter-name>AsynServlete</filter-name>

   <filter-class>com.kad.app.action.AsynServletT</filter-class>

    <async-supported>true</async-supported>

     <init-param>

            <param-name>encoding</param-name>

            <param-value>UTF-</param-value>

        </init-param>

</filter>

<filter-mapping>

    <filter-name>AsynServlete</filter-name>

   <url-pattern>/</url-pattern>

</filter-mapping>

http://localhost:8080/AppService/asyncServlet/testAsyn?

用上边地址请求, 爆错,

严重: Servlet.service() for servlet [applicationContext] in context with path [/AppService] threw exception [Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.servlet.FilterChain]: Specified class is an interface] with root cause

org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.servlet.FilterChain]: Specified class is an interface

    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:)

    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:)

    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:)

奇怪了这个异步以前用着很正常的, 就因为我注释了一下再打开, 出了问题......这个问题磨蹭到下午..............

起先是部署到resin 里边,程序爆错. 中间担心resin 的支持servlet 3.0 跟tomcat 有区别. 我想换成另一种不在web.xml filter 的方式,
@WebServlet(asyncSupported=true,urlPatterns="/asyncComplete") 这种多方便不用一个个写过滤的, 结果这种方式也也需要继承一个接口HttpServlet.

还是换成webserlet的方式吧...

后来发现web filter 过滤的方式,过滤url-pattern 后边的/需要加上*号 .还是建议用webservlet的方式

这种异步有两种实现方式,一个是另起一个异步线程,另一种是线程池,请求过来的链接放到线程池里边处理,这种一般应用于并发比较大的情况.

为了保留过滤的方式在此记录上过滤的方式先配置web.xml 设置一条过滤规则

com.kad.app.action.AsynServlet  这个是项目内接受异步请求的类

<filter>

   <filter-name>AsynServlete</filter-name>

   <filter-class>com.kad.app.action.AsynServlet</filter-class>

    <async-supported>true</async-supported>

     <init-param>

            <param-name>encoding</param-name>

            <param-value>UTF-</param-value>

        </init-param>

</filter>

<filter-mapping>

    <filter-name>AsynServlete</filter-name>

   <url-pattern>/*</url-pattern>

</filter-mapping>

还得把servlet 下加上

<servlet>
<servlet-name>applicationContext</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-common.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<async-supported>true</async-supported>
</servlet>

下边

/*package com.kad.app.action;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.AsyncContext;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.annotation.WebServlet;

import org.springframework.context.event.EventListener;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import com.google.common.eventbus.Subscribe;

import com.google.gson.Gson;

import com.kad.app.action.eventregservice.MessageEventReg;

import com.kad.app.redis.impl.RedisImpl;

import com.kad.dev.manage.DevNoOne;

import com.kad.guavaevents.messge.RTUnLockMessage;

import com.kad.netty.service.kdNettyServer;

@Controller

@RequestMapping("/asyncServlet")

public class AsynServlet implements Filter

{

    @Override

    public void init(FilterConfig filterConfig) throws ServletException {

        // TODO Auto-generated method stub

    }

 @RequestMapping(value="/testAsyn")

  @Override

    public void doFilter(ServletRequest request, ServletResponse response,

            FilterChain chain) throws IOException, ServletException {

  request.setAttribute("org.apache.catalina.ASYNC_SUPPORTED", true);

    //    System.out.println("start");

            PrintWriter out = response.getWriter();

            AsyncContext asyncContext = request.startAsync();

            asyncContext.setTimeout(5000);

            asyncContext.addListener(new MyAsyncListener());

            Work work=new Work(asyncContext,request);

            new Thread(work).start();

               response = asyncContext.getResponse();

            // PrintWriter  out1 = response.getWriter();

           out.print("异步执行中");

    }

    @Override

    public void destroy() {

   }

class Work  implements Runnable

{

    private AsyncContext asyncContext;

    private ServletRequest request;

    public Work(AsyncContext asyncContext,ServletRequest request)

    {

        this.asyncContext = asyncContext;

        this.request = request;

      //  EventBusCenter.register(this);

    }

    @Override

    public void run()

    {

          ServletResponse   response = asyncContext.getResponse();

             PrintWriter out;

            try {

                out = response.getWriter();

                 out.println("后台线程执行完成");

                    out.close();

            } catch (IOException e2) {

                // TODO Auto-generated catch block

                e2.printStackTrace();

            }

        String devid =request.getParameter("devid");

        //   PrintWriter  out = response.getWriter();

                boolean sign=false;

                DevNoOne dev=    DevNoOne.devone;

                 RedisImpl redis =new RedisImpl();

            while(true){

               try {

                 //  out.println("后台线程执行完成");

                Thread.sleep(100);

            } catch (InterruptedException e1) {

                // TODO Auto-generated catch block

                e1.printStackTrace();

            }

               String mess=null;

               mess=    redis.get(devid);

               if(mess!=null) {

                    if(request.getAsyncContext() != null && asyncContext.getTimeout()>0){

                       // try {

                         ServletResponse   response = asyncContext.getResponse();

                         PrintWriter  out = response.getWriter();

                            out.println("后台线程执行完成");

                            out.close();

                    //    } catch (IOException e) {

                        //    e.printStackTrace();

                      //  }

                        asyncContext.complete();

                        break;

                           }

                }

          }

    }

}

}

*/

这种似乎是一种土方子.... 中间还必须加

一下是第二种方式  简单明了,继承 extends HttpServlet   ,重写doGet 或doPost 也就是你用get方法请求就重写doget ,用post 就重写dopost  
下边程序异步work类里边逻辑没写好,不影响测试.最后的报错跟异步无关.先写上来.调试过程中间有个报错 用post方式请求. 半道出家基础不牢靠啊...

 Status  - HTTP method POST is not supported by this URL

这是指重写了doget 没重写dopost导致......

package com.kad.app.action;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.AsyncContext;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;

@WebServlet(asyncSupported=true,urlPatterns="/asyncweb")

public class AsynWebServlet  extends HttpServlet{

    /**

     *

     */

    private static final long serialVersionUID = 1L;

/*    @Override

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException{

        // request.setAttribute("org.apache.catalina.ASYNC_SUPPORTED", true);

        System.out.println("start");

            PrintWriter out = response.getWriter();

            AsyncContext asyncContext = request.startAsync();

            asyncContext.setTimeout(500000);

            asyncContext.addListener(new MyAsyncListener());

            Work work=new Work(asyncContext,request);

            new Thread(work).start();

            out.print("异步执行中");

    }*/

    @Override

     protected void doPost(HttpServletRequest request, HttpServletResponse response)

                throws ServletException, IOException

            {

        System.out.println("start");

        PrintWriter out = response.getWriter();

        AsyncContext asyncContext = request.startAsync();

        asyncContext.setTimeout();

        asyncContext.addListener(new MyAsyncListener());

        Work work=new Work(asyncContext,request);

        new Thread(work).start();

        out.print("异步执行中");

            }

    class Work implements Runnable

    {

        private AsyncContext asyncContext;

        private ServletRequest request;

        public Work(AsyncContext asyncContext,ServletRequest request)

        {

            this.asyncContext = asyncContext;

            this.request = request;

        }

        @Override

        public void run() {      

            if(request.getAsyncContext() != null && asyncContext.getTimeout()>){

                try {

                     ServletResponse   response = asyncContext.getResponse();

                     PrintWriter  out = response.getWriter();

                    out.println("后台线程执行完成");

                    out.close();

                } catch (IOException e) {

                    e.printStackTrace();

                }

                asyncContext.complete();

            }

          }

    }

}

周日传到服务器上

出现了500 错误,

HTTP Status  – Internal Server Error

Type Exception Report

Message Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Could not open connection

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Could not open connection

    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:)

    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:)

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

    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:)

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

    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:)

    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal

服务器内部错误, 最终是因为本地测试用的数据库的表名与线上的表名名字大小写存在不同...linux 对大小写很敏感....

码农公寓

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