关于Web中资源跳转的问题：
转发和重定向基本代码：
1 package com.bjpowernode.javaweb;
2
3 import java.io.IOException;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.http.HttpServlet;
7 import javax.servlet.http.HttpServletRequest;
8 import javax.servlet.http.HttpServletResponse;
9
10 public class AServlet extends HttpServlet {
11
12 private static final long serialVersionUID = 1L;
13
14 @Override
15 protected void doGet(HttpServletRequest request, HttpServletResponse response)
16 throws ServletException, IOException {
17 //向request范围中存储数据
18 request.setAttribute("username", "zhangsan");
19
20 //转发forward：一次请求
21 //request.getRequestDispatcher("/b").forward(request, response);
22
23 //重定向redirect：两次请求
24 //执行到此处之后，将/prj-servlet-16/b路径响应给浏览器，浏览器又向服务器发送了一次全新的请求
25 response.sendRedirect("/prj-servlet-16/b");
26 //response.sendRedirect(request.getContextPath() + "/b");
27 }
28 }
1 package com.bjpowernode.javaweb;
2
3 import java.io.IOException;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.http.HttpServlet;
7 import javax.servlet.http.HttpServletRequest;
8 import javax.servlet.http.HttpServletResponse;
9
10 public class BServlet extends HttpServlet {
11
12 private static final long serialVersionUID = 1L;
13
14 @Override
15 protected void doGet(HttpServletRequest request, HttpServletResponse response)
16 throws ServletException, IOException {
17 //向request范围中取数据
18 Object obj = request.getAttribute("username");
19 System.out.println(obj);
20 }
21 }
使用重定向解决页面刷新问题：
1 <html> 2 <head> 3 <title>save user</title> 4 <meta charset="UTF-8"> 5 </head> 6 <body> 7 <form action="/prj-servlet-17/save" method="post"> 8 usercode<input type="text" name="usercode"> 9 username<input type="text" name="username"> 10 <input type="submit" value="save"> 11 </form> 12 </body> 13 </html>
1 package com.bjpowernode.javaweb.servlet;
2
3 import java.io.IOException;
4 import java.sql.Connection;
5 import java.sql.DriverManager;
6 import java.sql.PreparedStatement;
7 import java.sql.SQLException;
8
9 import javax.servlet.ServletException;
10 import javax.servlet.http.HttpServlet;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpServletResponse;
13
14 public class SaveUserServlet extends HttpServlet {
15
16 private static final long serialVersionUID = 1L;
17
18 @Override
19 protected void doPost(HttpServletRequest request, HttpServletResponse response)
20 throws ServletException, IOException {
21 //解决中文乱码
22 request.setCharacterEncoding("UTF-8");
23
24 //获取表单提供的数据
25 String usercode = request.getParameter("usercode");
26 String username = request.getParameter("username");
27
28 //JDBC
29 Connection conn = null;
30 PreparedStatement ps = null;
31 int count = 0;
32 try{
33 Class.forName("com.mysql.jdbc.Driver");
34 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test1", "root", "248xiaohai");
35 conn.setAutoCommit(false);
36 String sql = "insert into t_user(usercode,username) values(?,?)";
37 ps = conn.prepareStatement(sql);
38 ps.setString(1, usercode);
39 ps.setString(2, username);
40 count = ps.executeUpdate();
41 conn.commit();
42 } catch (Exception e) {
43 e.printStackTrace();
44 } finally {
45 if(ps != null){
46 try {
47 ps.close();
48 } catch (SQLException e) {
49 e.printStackTrace();
50 }
51 }
52 if(conn != null){
53 try {
54 conn.close();
55 } catch (SQLException e) {
56 e.printStackTrace();
57 }
58 }
59
60 if(count == 1){
61 //保存成功，跳转到成功页面
62 //转发,刷新的时候会重复保存数据,因为刷新的是第一个请求/prj-servlet-17/save
63 //request.getRequestDispatcher("/success.html").forward(request, response);
64 //重定向,刷新的时候不会重复保存数据,因为刷新的是后一个请求/prj-servlet-17/success.html
65 response.sendRedirect(request.getContextPath() + "/success.html");
66 }
67 }
68 }
69
70
71 }
时间： 2024-12-28 23:52:20