Servlet实现用户数的统计

太过爱你忘了你带给我的痛 2022-08-03 05:16 150阅读 0赞

实现访问用户数的统计，本质上就是统计启动过多少新的会话，因为一个用户访问Web服务器可能有很多次，但是会话只有一次，利用会话监听器就可以很好的达到目的，然后再把这个数字变量保存在Servlet上下文中，最后提供一个Servlet来打印这个数字。

监听类：

/********************************
     *                 @Dream_EarFire
     ********************************/
    package com.dream.javaweb;
    
    import javax.servlet.ServletContext;
    import javax.servlet.http.HttpSession;
    import javax.servlet.http.HttpSessionEvent;
    import javax.servlet.http.HttpSessionListener;
    
    public class SessionCountListener implements HttpSessionListener{
    
    	@Override
    	public void sessionCreated(HttpSessionEvent httpSessionEvent) {
    		// TODO Auto-generated method stub
    		HttpSession session=httpSessionEvent.getSession();
    		ServletContext application =session.getServletContext();
    		Integer count=(Integer)application.getAttribute("count");
    		if(count==null)
    			count=0;
    		count++;
    		application.setAttribute("count", count);
    	}
    
    	@Override
    	public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
    		// TODO Auto-generated method stub
    		//会话销毁时什么也不做
    	}
    	
    }

显示访问用户数：

/********************************
     *                 @Dream_EarFire
     ********************************/
    package com.dream.javaweb;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletContext;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    public class ShowServlet extends HttpServlet{
    	/**
    	 * 
    	 */
    	private static final long serialVersionUID = 1L;
    	public void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
    		doPost(request,response);
    	}
    	public void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
    		response.setContentType("text/html;charset=utf-8");
    		HttpSession session=request.getSession();
    		ServletContext application=session.getServletContext();
    		PrintWriter out=response.getWriter();
    		out.println("<html>");
    		out.println("<head><title>A Servlet</title></head><body>");
    		out.println("已经有 "+application.getAttribute("count")+" 位用户访问本Web网站了");
    		out.println("</body>");
    		out.println("</html>");
    		out.flush();
    		out.close();
    	}
    }

web.xml配置

<listener>
      <listener-class>com.dream.javaweb.SessionCountListener</listener-class>
      </listener>
      <servlet>
      <servlet-name>ShowServlet</servlet-name>
      <servlet-class>com.dream.javaweb.ShowServlet</servlet-class>
      </servlet>
      <servlet-mapping>
      <servlet-name>ShowServlet</servlet-name>
      <url-pattern>/ShowServlet</url-pattern>
      </servlet-mapping>