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利用HttpServlet完成MySql数据库my_user表的登录校验

news 来源：原创 2024/9/20 22:33:46

功能：利用HttpServlet完成MySql数据库my_user表的登录校验

step1:在porm.xml文件中导jdbc的依赖

mysql数据库输入

SELECT VERSION()

查询当前的数据库版本

maven官网网址;https://mvnrepository.com/

maven官网中搜索：mySQL

并复制依赖粘贴到pom文件中

main函数下java包的class类

package com.iweb.demo03;import org.apache.commons.codec.digest.DigestUtils;import javax.servlet.RequestDispatcher;
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 java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;@WebServlet(value = "/login")
public class Login extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("utf-8");resp.setCharacterEncoding("utf-8");resp.setContentType("text/html");PrintWriter pw = resp.getWriter();String username = req.getParameter("username");String password = req.getParameter("password");password = DigestUtils.md5Hex(password);String sql = "select count(*) cou from my_user m " +"where m.username=? and m.password=?";List<Map<String, Object>> list = null;try {list = JDBCUtill.jdbcBySelect(sql, username, password);} catch (SQLException e) {throw new RuntimeException(e);} catch (ClassNotFoundException e) {throw new RuntimeException(e);}Map<String, Object> map = list.get(0);long cou = (long) map.get("cou");String path="";if (cou > 0) {/* pw.print("欢迎您"+username);//页面跳转*//* resp.sendRedirect("/demo03/test5.html");*/path=req.getContextPath() + "/test5.html";System.out.println("登录成功");} else {path=req.getContextPath()+"/login.html?islogin=0";}resp.sendRedirect(path);}
}

html文件：

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>用户登陆</title><script type="text/javascript">window.onload = function () {var urlParams = new URLSearchParams(window.location.search);var islogin = urlParams.get("islogin")if (islogin == 0) {alert("用户名或密码错误")}}</script>
</head>
<body>
<h3>用户登陆</h3>
<form method="post" action="login">账号<input type="text" name="username"><br/><br/>密码<input type="text" name="password"/><br/><br/><input type="submit" value="提交"/><br/>
</form>
<br/></body>
</html>

附录：

JDBC文件：

package com.iweb.demo03;//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;public class JDBCUtill {static Connection conn;static PreparedStatement pstat;static ResultSet rest;public JDBCUtill() {}private static void getSource() throws SQLException, ClassNotFoundException {Class.forName("com.mysql.cj.jdbc.Driver");conn = DriverManager.getConnection("jdbc:mysql://192.168.77.100:3306/mysql?characterEncoding=utf-8", "root", "123456");}private static void closeSource() throws SQLException {if (rest != null) {rest.close();}if (pstat != null) {pstat.close();}if (conn != null) {conn.close();}}public static List<Map<String, Object>> jdbcBySelect(String sql) throws SQLException, ClassNotFoundException {List<Map<String, Object>> list = new ArrayList();getSource();pstat = conn.prepareStatement(sql);rest = pstat.executeQuery();ResultSetMetaData rsmd = rest.getMetaData();int columnCount = rsmd.getColumnCount();while(rest.next()) {Map<String, Object> map = new HashMap();for(int i = 1; i <= columnCount; ++i) {String columnName = rsmd.getColumnName(i);Object columnValue = rest.getObject(i);map.put(columnName, columnValue);}list.add(map);}closeSource();return list;}public static List<Map<String, Object>> jdbcBySelect(String sql, String username, String password) throws SQLException, ClassNotFoundException {List<Map<String, Object>> list = new ArrayList();getSource();pstat = conn.prepareStatement(sql);pstat.setString(1, username);pstat.setString(2, password);rest = pstat.executeQuery();ResultSetMetaData rsmd = rest.getMetaData();int columnCount = rsmd.getColumnCount();while(rest.next()) {Map<String, Object> map = new HashMap();for(int i = 1; i <= columnCount; ++i) {String columnName = rsmd.getColumnName(i);Object columnValue = rest.getObject(i);map.put(columnName, columnValue);}list.add(map);}closeSource();return list;}public static <E> int updateBySql(String sql, E... e) throws SQLException, ClassNotFoundException {getSource();int res=0 ;pstat = conn.prepareStatement(sql);for(int i = 0; i < e.length; ++i) {pstat.setObject(i + 1, e[i]);}res = pstat.executeUpdate();closeSource();return res;}
}