JSP访问数据库

1.创建表login：

creat tables login{uname varchar(20),upwd varchar(20)}

并在表中添加帐号和密码：

insert into join(uname,upwd)
values('zs','abc');

2.在eclipse中创建MyWebProject工程，并添加index.jsp和check.jsp

3.将mysql java 8.0.14 jar复制到WEB-INF/lib中

4.在index.jsp中输入代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body><form action="check.jsp" method="post">
    用户名：<input type="text" name="uname"/><br/>
    密码：<input type="password" name="upwd"/><br/>
     <input type="submit" value="登录"/><br/>
    </form>
</body>
</html>

5.在check.jsp中输入代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<% 
        String URL = "jdbc:mysql://localhost:3306/myemployees?serverTimezone=UTC";
         String USERNAME = "root";
         String PWD = "123456";
        
        Connection connection = null;
        Statement stmt=null; 
        ResultSet rs=null; //返回值表示增删改第几条数据
    
        try {
            //a.导入驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            //b.与数据库进行连接
            connection=DriverManager.getConnection(URL,USERNAME,PWD);
            //c.发送sql,执行查找
            stmt=connection.createStatement();
            //把名字密码一收
            String name=request.getParameter("uname");
            String pwd=request.getParameter("upwd");
            
             String sql="select count(*) from login where uname='"+name+"' and upwd='"+pwd+"'";

            
            
            rs=stmt.executeQuery(sql);//返回值表示增删改第几条数据
            
            //d.处理结果
            int count=-1;
            if(rs.next()) {
                count=rs.getInt(1);
            }
                if(count>0){
                    out.println("登录成功！");
                }
                else{
                out.println("登录失败！");
            }
        }catch(ClassNotFoundException e){
            e.printStackTrace();
            }
            catch(SQLException e) {
                e.printStackTrace();
            }catch(Exception e) {
                e.printStackTrace();
            }finally {
                try {if(rs!=null){
                    rs.close();
                }
                    if(stmt!=null) {
                        stmt.close();
                    }if(connection!=null) {
                        connection.close();
                    }
                }catch(SQLException e) {
                    e.printStackTrace();
                }
            }
        %>
</body>
</html>

6.开始运行，并在浏览器中输入：

http://localhost:9999/MyWebProject/index.jsp

7.zs,abc 登录成功