Java Web------Session实例

1、用户在初始化页面输入一个值，单击“提交按钮”，会进入第一个Servlet；第一个Servlet将输入的值分别保存到request和Session中；在第二个Servlet中从request和Session对象中提取信息并显示。

（1）编写session.html页面，代码如下：

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<center>
<form method = "get" action = "s1">
    <table>
        <tr>
            <td>输入数据：<input type = "text" name = "count"></td>
        </tr>
    </table>
    <center><input type = "submit" value = "提交"></center>
</form>
</center>
</body>
</html>

（2）编写FirstServelt.java页面，代码如下：

package session;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class FirstServlet
 */
@WebServlet("/FirstServlet")
public class FirstServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public FirstServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("GBK");
        response.setContentType("text/html;charset=GBK");
        PrintWriter out = response.getWriter();
        String str = request.getParameter("count");
        request.setAttribute("request_param", str);
        HttpSession session = request.getSession();
        session.setAttribute("session_param",str);
        out.println("<a href = 's2'>下一页</a>");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

}

（3）编写SecondServlet.java，代码如下：

package session;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class SecondServlet
 */
@WebServlet("/SecondServlet")
public class SecondServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public SecondServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        Object obj = request.getAttribute("request_param");
        String request_param = null;
        if(obj != null) {
            request_param = obj.toString();
        } else {
            request_param = "null";
        }
        HttpSession session = request.getSession();
        Object obj2 = session.getAttribute("session_param");
        String session_param = null;
        if(obj2 != null) {
            session_param = obj2.toString();
        } else {
            session_param = "null";
        }
        response.setContentType("text/html;charset=GBK");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<body>");
        out.println("<h2>请求对象中的参数是:" + request_param + "</h2>");
        out.println("<h2>Session对象中的参数是："+session_param+"</h2></body></html>");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

}

（4）web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>Learning-JavaWeb</display-name>
  <servlet>
    <servlet-name>firstServlet</servlet-name>
    <servlet-class>session.FirstServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>firstServlet</servlet-name>
    <url-pattern>/s1</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>secondServlet</servlet-name>
    <servlet-class>session.SecondServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>secondServlet</servlet-name>
    <url-pattern>/s2</url-pattern>
  </servlet-mapping>
</web-app>

这里写图片描述

Java Web------Session实例

1、用户在初始化页面输入一个值，单击“提交按钮”，会进入第一个Servlet；第一个Servlet将输入的值分别保存到request和Session中；在第二个Servlet中从request和Session对象中提取信息并显示。

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