JSP Basics Primer JAVAWeb

But also to the exam week, many lessons were quite ready to learn something new. Then he began to teach himself JAVAWeb.

To learn JAVAWeb, you first need the following information:

a) HTML / CSS / JS (front page), XML, JSON, vue

b) Servlet / JSP (J2EE) (server)

c) Mysql (Database): navicat, sqlyog

Here is a little basic knowledge of JSP I sort of hope that can give people new to JSP to a sort of knowledge.

(Due to the background of the page, the picture will not see some recommend the right mouse button to open the picture in a new tab)

https://img2018.cnblogs.com/common/1642097/201912/1642097-20191218190022655-737388987.jpg

Here is what I use to write JSP basics of a user login screen (running locally)

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8"
 6     pageEncoding="UTF-8"%>
 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 8 <title>登录界面</title>
 9 </head>
10 <body>
11 <div>
12     <%
13         Object error = session.getAttribute("error");
14         if(error!=null){
15         %>
16         <span style="color:red"><%=error %></span>
17     <%}%>
18     
19     
20 
21 </div>
22     <h1>登录界面</h1>
23     <!--action 提交请求的地址 method 处理请求的方式  -->
24     <form action="loginpost.jsp" method="post">
25     <!-- get请求：http://localhost:8080/web/userService.jsp?userName=123&userPassword=123456&userLike=readbook -->
26     <!-- post请求：http://localhost:8080/web/userService.jsp get请求会把表单的数据输出出来-->
27         <table>
28             <tr>
29                 <td>用户名：</td>
30                 <td><input type="text" name="userName" /></td>
31             </tr>
32             <tr>
33                 <td>密码：</td>
34                 <td><input type="password" name="userPassword" /></td>
35             </tr>
36             <tr>
37                 <td><input type="submit"   value="登录"/></td>
38             </tr>
39         </table>
40 
41 
42 
43 
44     </form>
45 </body>
46 </html>

View Code

loginpost.jsp（通过数据库来判断账号和密码是否正确）

若正确就跳转到main.jsp中，如果不正确就跳转回login.jsp进行重新输入

ps：代码里面涉及数据库的部分需要自己来改一下

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8"
 6     pageEncoding="UTF-8"%>
 7 <%@ page import="java.sql.*" %>
 8 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 9 <title>在此处插入标题</title>
10 </head>
11 <body>
12 <%     //用request获得传入的参数
13     String userName = request.getParameter("userName");//接受用户名
14     String userpassword = request.getParameter("userPassword");//接受密码
15     
16     //连接数据库
17     Connection con=null; //用于储存连接信息
18     Statement sql;    //声明sql语句对象
19     ResultSet rs;    //数据行对象
20     //对于数据库的连接测试->这里指加载JDBC-Mysql驱动
21     try {
22         Class.forName("com.mysql.cj.jdbc.Driver");//加载JDBC-Mysql驱动
23     }
24     catch(Exception e) {
25         System.out.println("驱动加载失败");
26     }
27     //主机名+ip地址+端口+时区
28     String uri = "jdbc:mysql://localhost:3306/students?useSSL=true&serverTimezone=UTC";
29     String user ="root";//用户名
30     String password = "123456";//输入数据库的密码
31     try {
32         con = DriverManager.getConnection(uri,user,password);
33     }
34     catch(SQLException e) {
35         System.out.println("连接失败");
36     }//检测sql库的连接
37     try {
38         session.setAttribute("error",null);
39         sql = con.createStatement();
40         String  c1 = "SELECT * FROM shopper where username='"+userName+"'";
41         rs = sql.executeQuery(c1);//查询
42         if(rs.next())//判断用户是否存在
43         {
44             //获取密码：
45             String pwd = rs.getString("password");
46             //判断用户名和密码是否相等
47             if(pwd.equals(userpassword))
48             {
49                 session.setAttribute("user", userName);
50                 response.sendRedirect("main.jsp");
51             }
52             else{
53                 session.setAttribute("error", "用户名或密码错误");
54                 response.sendRedirect("login.jsp");
55             }
56         }
57         else
58         {
59             session.setAttribute("error", "用户名或密码错误");
60             response.sendRedirect("login.jsp");
61         }
62         con.close();//关闭连接
63     }
64     catch(SQLException e) {
65         System.out.println(e);
66     }
67 %>
68 </body>
69 </html>

View Code

main.jsp（跳转的主页面）

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8"
 6     pageEncoding="UTF-8"%>
 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 8 <title>在此处插入标题</title>
 9 </head>
10 <body>
11 <h1>hello</h1>
12 </body>
13 </html>

View Code

JSP Basics Primer JAVAWeb

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