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区别在于session是局部的,servletContext是共享的.

session 保留用户的当前连接信息。

session.setAttrubute()把参数放入session中。

要理解问什么要session 就要理解B/S的工作原理了

1，client发出请求

2，server返回相应

3，中断连接

和平县教育局

这是一个完整的过程这样就不能保留用户的信息所以诞生了Session

//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.*;

/* Servlet实现访问次数的例子

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 = Session();

茱莉亚罗伯兹String heading;

Integer accessCount =(Attribute("accessCount");

if(accessCount == null) {

accessCount = new Integer(0);

heading = "Welcom,You are first time to visit!";

}

else {

heading = "Welcome Backer"; 水泥电阻

accessCount = new Integer(accessCount.intValue()+1);

}

session.setAttribute("accessCount",accessCount);

PrintWriter out = Writer();

out.println("The title:"+heading);

out.println("Access count: "+accessCount);

}

public void doPost(HttpServletRequest request,HttpServletResponse response)

throws ServletException, java.io.IOException {

央妈严控第三方支付doGet(request,response);

}

猴耳环}

下面是通过servleContext来做访问次数

Java代码

package st;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletContext;

麦大成

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 = ServletContext();

Integer accessCount =(Attribute("accessCount");

if(accessCount == null){

accessCount = 0;

}else{

accessCount = accessCount + 1;

}

servletContext.setAttribute("accessCount", accessCount);

PrintWriter out = Writer();

out.println("<html><body><h2>"+accessCount+"</body></html>");

}

@Override

protected void doPost(HttpServletReque

st 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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