JAVA高级面试进阶训练营视频教程

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<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-8</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:99)
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:778)
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:371)

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-8</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 405 - 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(500000);            
        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()>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();
            }
      
          }
    }


}

 周日传到服务器上

出现了500 错误,

HTTP Status 500 – 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:982)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    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....