源码:

AServlet.java

 1 package one.servlet;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.ServletContext;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 public class AServlet extends HttpServlet {
13 
14     public void doGet(HttpServletRequest request, HttpServletResponse response)
15             throws ServletException, IOException {
16         ServletContext context=this.getServletContext();
17         Integer count = (Integer)context.getAttribute("count");
18         if(count==null){
19             context.setAttribute("count", 1);
20         }else{
21             context.setAttribute("count", count+1);
22         }
23         count = (Integer)context.getAttribute("count");//重新获取count的值
24         //向浏览器输出,用到响应对象!
25         PrintWriter pw=response.getWriter();
26         pw.print("<h1>requested count:"+count+"</h1>");//把这个数字输出到浏览器
27     }
28 }

BServlet.java

 1 package one.servlet;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.ServletContext;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 public class BServlet extends HttpServlet {
13 
14     public void doGet(HttpServletRequest request, HttpServletResponse response)
15             throws ServletException, IOException {
16         ServletContext context=this.getServletContext();
17         Integer count = (Integer)context.getAttribute("count");
18         if(count==null){
19             context.setAttribute("count", 1);
20         }else{
21             context.setAttribute("count", count+1);
22         }
23         count = (Integer)context.getAttribute("count");//重新获取count的值
24         //向浏览器输出,用到响应对象!
25         PrintWriter pw=response.getWriter();//流
26         pw.print("<h1>requested count:"+count+"</h1>");//把这个数字输出到浏览器
27     }
28 }

不管是访问AServlet还是BServlet ,都会统计它们被请求的次数;如果关掉Tomcat(服务器),计数就会随ServletContext而死亡。

 

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