javaWeb 使用session保持会话

水深无声 2023-06-19 14:30 18阅读 0赞

jsp文件

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html>
    <html>
    <head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    	<h2>请选择要购买的书籍：</h2>
    	<Form action="ShoppingCarServlet"method ="POST">
    		<p> <input type="checkbox" name="book" value="书籍1"/>书籍1</p>
    		<p> <input type="checkbox" name="book" value="书籍2"/>书籍2</p>
    		<p> <input type="checkbox" name="book" value="书籍3"/>书籍3</p>
    		<p> <input type="submit" value="提交"/></p>
    	</Form>
    </body>
    </html>

Java 处理类：

package com.my.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.HashMap;
    
    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;
    
    import com.sun.javafx.collections.MappingChange.Map;
    
    /**
     * Servlet implementation class ShoppingCarServlet
     */
    @WebServlet("/ShoppingCarServlet")
    public class ShoppingCarServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
           
        /**
         * @see HttpServlet#HttpServlet()
         */
        public ShoppingCarServlet() {
            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
    		response.getWriter().append("Served at: ").append(request.getContextPath());
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");
    		response.setContentType("text/html;charset=UTF-8");
    		PrintWriter out = response.getWriter();
    		
    		HttpSession session = request.getSession();//获得session对象
    		
    		HashMap<String, Integer> car = (HashMap<String, Integer>)session.getAttribute("shoppingCar");//获得请求头中的属性
    		if(car==null)car= new HashMap<String,Integer>();
    		
    		String[] books = request.getParameterValues("book");
    		if(books!=null && books.length>0) {
    			for(String bookName:books) {
    				
    				if(car.get("bookName")!=null) {
    					int num=car.get(bookName);
    					car.put(bookName,num+1);
    				}else{
    					car.put(bookName,1);
    				}				
    			}
    		}
    		
    		session.setAttribute("shoppingCar", car);
    		response.sendRedirect("ShoppingListServlet");
    		
    	}
    
    }

Java显示类：

package com.my.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.HashMap;
    
    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 ShoppingListServlet
     */
    @WebServlet("/ShoppingListServlet")
    public class ShoppingListServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
           
        /**
         * @see HttpServlet#HttpServlet()
         */
        public ShoppingListServlet() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");
    		response.setContentType("text/html;charset=UTF-8");
    		
    		HttpSession session = request.getSession();//获得session对象
    		HashMap<String, Integer> car = (HashMap<String, Integer>)session.getAttribute("shoppingCar");//获得请求头中的属性
    		
    		PrintWriter out = response.getWriter();
    		
    		if(car!=null&&car.size()>0){
    			out.println("<p>您购买的书籍有：</p>");
    			for(String name:car.keySet()) {
    				out.println("<p>"+name+"</p>"+","+car.get(name)+"本</p>");
    			}
    		}
    		out.println("<p><a href='bookChose.jsp'>继续购买</a></p>");
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		doGet(request, response);
    	}
    
    }