jsp登录（mysql数据库）

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从网页上获取的用户信息连接数据库进行校验，首先要有网页进行提交表单，通过servlet来读取其中的信息，再拿来与数据库中的数据进行比较。

我们来看一下login.html

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>Title</title></head><body>    <form action="LoginServlet3" method="post">        user:<input type="text" name="username"/>        password:<input type="password" name="password"/>        <input type="submit" value="submit"/>    </form></body></html>

我们再来看一下servlet，我直接将数据库的连接写在了servlet立里面这样写其实是不规范的。

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.*;/** * Created by yuehailin on 2017/7/15. */@WebServlet(name = "LoginServlet3")public class LoginServlet3 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        String username =request.getParameter("username");        String password =request.getParameter("password");        PrintWriter out =response.getWriter();        Connection connection=null;        PreparedStatement statement;        statement = null;        ResultSet resultSet =null;        try {            Class.forName("com.mysql.jdbc.Driver");            System.out.print("ok");            String sql ="select count(id) from user where username=?"+"AND password=?";            connection= DriverManager.getConnection("jdbc:mysql://localhost:3306/bbs","root","123");            statement =connection.prepareStatement(sql);            statement.setString(1,username);            statement.setString(2,password);            resultSet =statement.executeQuery();            if(resultSet.next()){                int count=resultSet.getInt(1);                if(count>0)                {                    out.println("hello"+username);                }                else{                    out.println("sorry"+username);                }            }        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if(resultSet!=null)                {                    resultSet.close();                }            }catch (SQLException e){                e.printStackTrace();            }            try {                if(statement!=null)                {                    statement.close();                }            }catch (SQLException e){                e.printStackTrace();            }            try {                if(connection!=null)                {                    connection.close();                }            }catch (SQLException e){                e.printStackTrace();            }        }    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException    {    }}

在写javaweb项目的时候大家要注意在xml中进行配置，或者通过注入的方式，但是注入的方式仅限于3.0
之后。

希望对大家的学习有所帮助。

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