ssession和servletContext的比较，Servlet实现访问次数的例子
本文转自：http://linweihan.iteye.com/blog/125777作者：上帝也犯困
下面是Servlet实现访问次数的例子
//ShowTimesServlet.java /*Servlet实现访问次数的例子!*/import java.io.*;import java.util.zip.*;import javax.servlet.*;import javax.servlet.http.*;/* 这个类实现访问次数。显示访问次数！看是第几次访问！*/public class ShowTimesServlet extends HttpServlet { public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, java.io.IOException { response.setContentType("text/html"); HttpSession session = request.getSession(); String heading; Integer accessCount =(Integer)session.getAttribute("accessCount"); if(accessCount == null) { accessCount = new Integer(0); heading = "Welcom,You are first time to visit!"; } else { heading = "Welcome Backer"; accessCount = new Integer(accessCount.intValue()+1); } session.setAttribute("accessCount",accessCount); PrintWriter out = response.getWriter(); out.println("The title:"+heading); out.println("Access count: "+accessCount); } public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, java.io.IOException {doGet(request,response); }} 下面是通过servleContext来做访问次数
package org.linweihan.test;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;public class TestServletContext extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {ServletContext servletContext = this.getServletContext();Integer accessCount =(Integer)servletContext.getAttribute("accessCount");if(accessCount == null){ accessCount = 0;}else{ accessCount = accessCount + 1; }servletContext.setAttribute("accessCount", accessCount);PrintWriter out = response.getWriter();out.println("<html><body><h2>"+accessCount+"</body></html>"); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { }} 区别在于session是局部的,servletContext是共享的.
当换了另一个窗口开始访问又从0开始计数,而servletContext则是接下去计数.
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