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【Servlet-1】登录界面

数据库:

DROP TABLE IF EXISTS t_user;
CREATE TABLE t_user(
id INT(10),
username VARCHAR(32) NOT NULL,
PASSWORD VARCHAR(32) NOT NULL);
INSERT INTO t_user(id,username,PASSWORD) VALUES(1,'admin','123');
INSERT INTO t_user(id,username,PASSWORD) VALUES(2,'zhangsan','123');
COMMIT;
SELECT * FROM t_user;

在这里插入图片描述
login.html文件:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/29/LoginServlet" method="post">
    username <input type="text" name="username"><br>
    password <input type="password" name="password"><br>
    <input type="submit" value="login">
</form>

</body>
</html>

LoginServlet文件:

package Login;

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.sql.*;

@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置字符编码方式
        request.setCharacterEncoding("UTF-8");
        //获取用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        //链接数据库验证用户名和密码
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs= null;
        boolean loginSuccess=false;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn= DriverManager.getConnection("jdbc:mysql://localhost:3366/db1","root","123");
            conn.setAutoCommit(false);
            String sql ="select * from t_user where username=? and password=?";
            ps=conn.prepareStatement(sql);
            ps.setString(1,username);
            ps.setString(2,password);
            rs = ps.executeQuery();
            if(rs.next()){
                loginSuccess=true;
            }
            conn.commit();

        } catch (ClassNotFoundException | SQLException e) {

            if(conn!=null){
                try {
                    conn.rollback();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }
            e.printStackTrace();
        }finally {

            if(rs!=null){
                try {
                    conn.rollback();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }

            if(ps!=null){
                try {
                    ps.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            //登录成功调整需到登录页面,失败跳转到失败页面
            if(loginSuccess){
                response.sendRedirect(request.getContextPath()+"/welcome.html");
            }else{
                response.sendRedirect(request.getContextPath()+"/fail.html");

            }
        }
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

welcome.html文件:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
welcome
</body>
</html>

fail.html文件:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
登录失败,请重新 <a href="/29/login.html">登录</a>
</body>
</html>

【Servlet-1】登录界面插图1

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