servlet层中的UserLoginServlet.java
package com.mhys.servlet; /*** ClassName: ${NAME}* Description:** @Author 数开_11* @Create 2024-05-29 20:32* @Version 1.0*/import com.mhys.pojo.User;
import com.mhys.service.UserService;
import com.mhys.service.impl.UserServiceImpl;import javax.naming.Name;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.lang.annotation.Repeatable;
import com.mhys.servlet.UserLoginServlet;
@WebServlet(name = "UserLoginServlet",value = "/UserLoginServlet")
public class UserLoginServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request,response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("utf-8");String name = request.getParameter("name");String pwd = request.getParameter("pwd");// 创建userServletUserService service = new UserServiceImpl();User user = service.findByNameAndPassword(name, pwd);if (user != null) {request.getRequestDispatcher("/index.jsp").forward(request, response);
// response.sendRedirect("/login.jsp");} else {request.setAttribute("msg", "user/pwd错误哦");request.getRequestDispatcher("/login.jsp").forward(request, response);
// response.sendRedirect("login.jsp");}}
}
创建servlet映射对应到页面表单的跳转
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head><style>.centered-element{margin: 300px auto ;width: 200px;display: block;}</style><meta charset="UTF-8" ><title>HadoopWebLogin</title>
</head>
<body><form action="/UserLoginServlet" class="centered-element">
<%-- 使用外部css来居中这个table--%><table class="centered-element">
<%-- caption标签定义了表格的标题--%><caption>用户登录</caption>
<%-- tr标签表示的时表格的row--%><tr>
<%-- td标签表示的是单元格cell--%><td>账户:</td>
<%-- input标签是一个输入的控件--%><td><input type="text" name="name"></td></tr><tr><td> 密码: </td><td><input type="text" name="pwd"></td></tr><tr><td><input type="submit" value="登录"></td><td><input type="reset" value="重置"></td></tr>
<%-- 从request域中拿info--%><tr><td colspan="2"><span style="color: red;">${msg}</span></td></tr></table></form></body>
</html>
submit之后去找servlet层中的UserLoginServlet.java 进行逻辑判断---> 重定向操作
注！： 这里必须要在web.xml中配置上！！！！！（我是在这里犯错了，U小写了，找了半天没看出了，笑晕）
<servlet> <servlet-name>UserLoginServlet</servlet-name><servlet-class>com.mhys.servlet.UserLoginServlet</servlet-class></servlet><servlet-mapping><servlet-name>UserLoginServlet</servlet-name><url-pattern>/UserLoginServlet</url-pattern></servlet-mapping>
这里的webservlet中的路径是严格区分大小写的，写错小个小点都会在登录时重定向报404找不到资源！！！！
另一个注意点：就是创建对象获取数据库中的user/pwd时new 数据类型是UserService 父类
不要是接口的实现类
utils 层中的JDBCUtils.java
package com.mhys.util;import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;/*** ClassName: JdbcUtils* Description:** @Author 数开_11* @Create 2024-05-29 17:46* @Version 1.0*/
public class JdbcUtils {public static Connection getConnection() throws Exception{Connection connection=null;try{//1-读取db.properties文件Properties properties=new Properties();InputStream in=JdbcUtils.class.getClassLoader().getResourceAsStream("db.properties");properties.load(in);//2-读取属性String driver=properties.getProperty("driver");String url=properties.getProperty("url");String username=properties.getProperty("username");String password=properties.getProperty("password");//3-注册驱动Class.forName(driver);//4-获取连接connection= DriverManager.getConnection(url,username,password);//5-日志打印连接信息System.out.println("连接信息: " + url + " " + username + " " + password);} catch (Exception e) {e.printStackTrace();throw new RuntimeException("数据库连接失败，请检查连接参数是否正确！");}return connection;}
}
和项目的资源目录下配置db.properties文件
内容：
driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:33306/javaweb?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8&useSSL=false
username=root
password=root
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