Servlet异步处理实战

本文链接： https://blog.csdn.net/chengqiuming/article/details/100590180

一编写异步处理的Servlet类

package lee;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;

import java.io.*;
import java.util.*;


@WebServlet(urlPatterns="/async",asyncSupported=true)
public class AsyncServlet extends HttpServlet
{
    @Override
    public void doGet(HttpServletRequest request
        , HttpServletResponse response)throws IOException,ServletException
    {
        response.setContentType("text/html;charset=GBK");
        PrintWriter out = response.getWriter();
        out.println("<title>异步调用示例</title>");
        out.println("进入Servlet的时间："
            + new java.util.Date() + ".<br/>");
        // 创建AsyncContext，开始异步调用
        AsyncContext actx = request.startAsync();
        // 设置异步调用的超时时长
        actx.setTimeout(60 * 1000);
        // 启动异步调用的线程，该线程以异步方式执行
        actx.start(new GetBooksTarget(actx));
        out.println("结束Servlet的时间："
            + new java.util.Date() + ".<br/>");
        out.flush();
    }
}

二异步线程类

package lee;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;

import java.io.*;
import java.util.*;


public class GetBooksTarget implements Runnable
{
    private AsyncContext actx = null;
    public GetBooksTarget(AsyncContext actx)
    {
        this.actx = actx;
    }
    public void run()
    {
        try
        {
            // 等待5秒钟，以模拟业务方法的执行
            Thread.sleep(5 * 1000);
            ServletRequest request = actx.getRequest();
            List<String> books = new ArrayList<String>();
            books.add("疯狂Java讲义");
            books.add("轻量级Java EE企业应用实战");
            books.add("疯狂Ajax讲义");
            request.setAttribute("books" , books);
            actx.dispatch("/async.jsp");
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

三视图

<%@ page contentType="text/html; charset=GBK" language="java"
    session="false"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<ul>
<c:forEach items="${books}" var="book">
    <li>${book}</li>
</c:forEach>
</ul>
<%out.println("业务调用结束的时间：" + new java.util.Date());
if (request.isAsyncStarted()) {
    // 完成异步调用
    request.getAsyncContext().complete();
}%>

四测试

Servlet异步处理实战

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