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

时间：2023-03-09 03:09:34
eclipse Filter web.xml 问题解决 异步请求@WebServlet 
<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,eclipse Filter web.xml 问题解决 异步请求@WebServlet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....