用servlet校验密码2

Posted 2021-11-23 june-6th

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用servlet校验密码2

一.实验目的

查询资料，解决java如何访问mysql数据库，用Mysql 创建数据库，建立一张用户表，用servlet校验用户名密码，只有在用户表中存在的用户才能登录到系统主页

二.实验过程

①新建链接设置好用户名及密码，新建数据库，新建表并在表中插入数据如图：

技术图片

②代码，大部分代码没有变化见前一个实验，主要是在java类文件中重新修改代码，建立与数据库的链接，并且读出数据分析:

package com.loginservlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet{
    private static final long serialVersionUID = 1L;
    
    String sql = null;
    Connection con = null;
    Statement sta = null;
    ResultSet rs = null;
    boolean isLogin = false;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub    
            req.setCharacterEncoding("UTF-8");
            resp.setContentType("text/html;charset=utf-8");
            //获取参数
            String username = req.getParameter("un");
            String password = req.getParameter("pw");
            PrintWriter printWriter = resp.getWriter();
            
            //连接数据库检测用户名和密码
            try{
                //连接数据库
                Class.forName("com.mysql.jdbc.Driver");
                con = DriverManager.getConnection("jdbc:mysql://localhost:3306/workdb?user=root&password=root&serverTimezone=UTC");
                sta = con.createStatement();
                sql="select password from login where username=‘"+username+"‘";
                rs = sta.executeQuery(sql);
                
                if(rs.next()){
                    String passw = rs.getString("password");
                    if(passw.equals(password)){
                        isLogin = true;
                    }else{
                        isLogin = false;
                    }
                }else{
                    isLogin = false;
                }
            }catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
            }finally {
                try {
                    if(rs!=null)
                        rs.close();
                    if(sta!=null)
                        sta.close();
                    if(con!=null)
                        con.close();
                } catch (Exception e2) {
                    // TODO: handle exception
                    e2.printStackTrace();
                }
            }
            
            if(isLogin){
                printWriter.write("用户名: "+username+"\\t\\n密码: "+password);
                printWriter.close();
            }
            else {
                printWriter.write("用户名或密码错误！");
            }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(req, resp);
    }

}