最简单的Servlet继承HttpServlet查询数据库登录验证 

<%--
  Created by IntelliJ IDEA.
  User: yunqing
  Date: 2017-12-06
  Time: 9:11
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>login</title>
  </head>
  <body>
      <form action="/LoginFromMysql" method="post">
        用户名：<input type="text" name="username">
        密码：<input type="password" name="password">
        <input type="submit" value="submit">
      </form>

  </body>
</html>

 

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <!-- 从数据库查询登录-->
    <servlet>
        <servlet-name>fromMysql</servlet-name>
        <servlet-class>com.yunqing.servlet.LoginFromMysql</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>fromMysql</servlet-name>
        <url-pattern>/LoginFromMysql</url-pattern>
    </servlet-mapping>
</web-app>

 

LoginFromMysql.java

package com.yunqing.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.*;

public class LoginFromMysql extends HttpServlet {

    public static final String url = "jdbc:mysql://localhost:3306/mybatis";
    public static final String name = "root";
    public static final String pass = "5678";

    Connection conn = null;
    PreparedStatement ps = null;
    ResultSet rs = null;

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
　　　　　//获取前端表单中的数据
        String username = req.getParameter("username");
        String password = req.getParameter("password");

        try {
            //需要添加mysql-connector-java-xxx-bin.jar(在idea中需要把jar包放到TomCAT的lib目录中)
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url,name,pass);
            String sql = "SELECT COUNT(id) FROM t_user t WHERE t.name = ? AND t.gender = ?";
            ps = conn.prepareStatement(sql);
            ps.setString(1,username);
            ps.setString(2,password);

            rs = ps.executeQuery();
            while (rs.next()) {
                int count = rs.getInt(1);
                if (count > 0) {
                    resp.getWriter().print("Success=" + username);
                } else {
                    resp.getWriter().print("Error=" + username + "BCZ");
                }
            }

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null) {
                    rs.close();
                }
                if (ps != null) {
                    ps.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }

        }
    }
}

 

posted @ 2017-12-12 09:35  云晴  阅读(4672)  评论(0)  编辑  收藏  举报