Spring MVC

什么是Spring MVC？

是Spring框架的一部分，是一个基于Java的Web开发框架，遵循经典的MVC设计模式。它通过分离应用程序的输入逻辑、业务逻辑和显示逻辑，帮助开发者构建灵活、可扩展且易于维护的Web应用程序。

MVC模式：

• Model（模型）：负责处理数据和业务逻辑，通常由JavaBean或POJO（Plain Old Java Object）组成，可能涉及服务层（Service）和数据访问层（DAO）。
• View（视图）：负责展示数据，支持多种视图技术（如JSP、Thymeleaf、FreeMarker等），通过逻辑视图名称与具体模板关联。
• Controller（控制器）：处理用户请求，协调模型和视图。通过注解（如@Controller）标识，并使用@RequestMapping等注解映射HTTP请求到具体方法。

核心组件：

• DispatcherServlet：前端控制器，接收所有请求并分发给对应的处理器（Handler），是Spring MVC的入口。
• HandlerMapping：根据请求URL找到对应的Controller方法（处理器）。
• HandlerAdapter：调用处理器方法，并将结果封装为ModelAndView对象（模型数据+视图名称）。
• ViewResolver：解析逻辑视图名称为具体的视图对象（如JSP页面），并渲染模型数据。

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_4_0.xsd"
         version="4.0">
    <!--1.注册DispatcherServlet-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--关联一个springmvc的配置文件:【servlet-name】-servlet.xml-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别-1-->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!--/ 匹配所有的请求；（不包括.jsp）-->
    <!--/* 匹配所有的请求；（包括.jsp）-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
    <welcome-file-list>
        <welcome-file>/WEB-INF/jsp/welcome.jsp</welcome-file>
    </welcome-file-list>
    <!-- 对请求进行过滤，防止乱码   -->
    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

springmvc-servlet.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
   <!-- 处理器映射器   -->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
    <!-- 处理器适配器   -->
<!--    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>-->
    <!-- 替换原来的处理器适配器 -->
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/>

    <!-- 启用组件扫描（扫描Service、DAO等包） -->
    <context:component-scan base-package="com.itcast.controller"/>
    <!-- 启用注解驱动（支持@RestController、@RequestBody等） -->
    <mvc:annotation-driven/>
    <!-- 配置静态资源处理 -->
    <mvc:resources mapping="/resources/**" location="/resources/"/>
    
    
    <!--视图解析器:DispatcherServlet给他的ModelAndView-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>
    
</beans>

使用Spring MVC框架的流程：

1.用户发送HTTP请求到DispatcherServlet。

<!--1.注册DispatcherServlet-->
<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--关联一个springmvc的配置文件:【servlet-name】-servlet.xml-->
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springmvc-servlet.xml</param-value>
    </init-param>
    <!--启动级别-1-->
    <load-on-startup>1</load-on-startup>
</servlet>
<!--/ 匹配所有的请求；（不包括.jsp）-->
<!--/* 匹配所有的请求；（包括.jsp）-->
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>	

2.DispatcherServlet通过HandlerMapping找到对应的Controller方法（处理器）。

 <!-- 处理器映射器   -->
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

/**
 * 根据bean名称确定处理器的URL路径列表。
 * 该方法主要用于将bean名称映射到一个或多个URL路径，从而实现请求到正确处理器的路由功能。
 * 
 * @param beanName bean的名称，可能是以"/"开头的路径
 * @return 包含所有对应处理器URL路径的字符串数组
 */
@Override
protected String[] determineUrlsForHandler(String beanName) {
    // 初始化用于存储URL路径的集合
    List<String> urls = new ArrayList<>();
    
    // 如果bean名称以"/"开头，则直接将其作为URL路径添加
    if (beanName.startsWith("/")) {
        urls.add(beanName);
    }
    
    // 获取bean名称的所有别名，这些别名也可能表示额外的URL路径
    String[] aliases = obtainApplicationContext().getAliases(beanName);
    for (String alias : aliases) {
        // 如果别名以"/"开头，则将其作为URL路径添加
        if (alias.startsWith("/")) {
            urls.add(alias);
        }
    }
    
    // 将URL路径集合转换为数组并返回
    return StringUtils.toStringArray(urls);
}

3.HandlerAdapter调用处理器方法，处理业务逻辑并返回ModelAndView。

<!-- 处理器适配器   -->
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

/**
 * 简单的控制器处理器适配器类，实现了HandlerAdapter接口
 * 该适配器用于处理符合Controller接口的处理器
 */
public class SimpleControllerHandlerAdapter implements HandlerAdapter {

    /**
     * 检查当前适配器是否支持给定的处理器
     * 
     * @param handler 需要检查的处理器对象
     * @return 如果处理器是Controller的实例，则返回true，否则返回false
     */
    @Override
    public boolean supports(Object handler) {
        return (handler instanceof Controller);
    }

    /**
     * 处理HTTP请求，并返回ModelAndView对象
     * 
     * @param request HTTP请求对象，包含请求数据
     * @param response HTTP响应对象，用于生成响应
     * @param handler 处理请求的控制器对象
     * @return ModelAndView对象，包含模型数据和视图信息
     * @throws Exception 如果处理请求时发生错误，则抛出异常
     */
    @Override
    @Nullable
    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        // 调用Controller类型处理器的handleRequest方法处理请求,返回ModelAndView
        return ((Controller) handler).handleRequest(request, response);
    }

    /**
     * 获取处理器的最后修改时间
     * 
     * @param request HTTP请求对象
     * @param handler 处理请求的处理器对象
     * @return 如果处理器实现了LastModified接口，则返回最后修改时间，否则返回-1L
     */
    @Override
    public long getLastModified(HttpServletRequest request, Object handler) {
        // 检查处理器是否实现了LastModified接口
        if (handler instanceof LastModified) {
            // 调用处理器的getLastModified方法获取最后修改时间
            return ((LastModified) handler).getLastModified(request);
        }
        // 如果处理器未实现LastModified接口，则返回-1L
        return -1L;
    }

}

4.ViewResolver根据视图名称解析具体的视图资源（如JSP页面）。

5.视图渲染模型数据，生成HTML等响应内容返回给用户。

SSM整合(登录案例)

项目结构

1.配置文件

1.1 pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.itcast</groupId>
    <artifactId>ssm</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>ssm</name>
    <packaging>war</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
        <junit.version>5.9.2</junit.version>
    </properties>

    <dependencies>
        <!--Junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <!--数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version> <!-- 根据实际需求选择版本 -->
        </dependency>
        <!-- 数据库连接池 -->
        <!-- 基础依赖 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.8</version> <!-- 根据需要选择版本 -->
        </dependency>

        <!--Servlet - JSP -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <!--Mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>
        <!--Spring-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>RELEASE</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>
</project>

1.2 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_4_0.xsd"
         version="4.0">
    <!--DispatcherServlet-->
    <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!--encodingFilter-->
    <filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>
            org.springframework.web.filter.CharacterEncodingFilter
        </filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <!--Session过期时间-->
    <session-config>
        <session-timeout>15</session-timeout>
    </session-config>

    <welcome-file-list>
        <welcome-file>/WEB-INF/jsp/login.jsp</welcome-file>
    </welcome-file-list>
</web-app>

1.3 applicationContext.xml(总配置):

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
    <import resource="spring-dao.xml"/>
    <import resource="spring-bean.xml"/>
    <import resource="spring-mvc.xml"/>
</beans>

1.4 spring-dao.xml(Spring和MyBatis整合):

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">
    <!-- 配置整合mybatis -->
    <!-- 1.关联数据库文件 -->
    <context:property-placeholder location="classpath:database.properties"/>
    <!-- 2.数据库连接池 -->
    <!--数据库连接池  -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="initialSize" value="1"/>
        <property name="maxActive" value="10"/>
        <property name="minIdle" value="1"/>
        <property name="maxWait" value="6000"/>
        <property name="timeBetweenEvictionRunsMillis" value="6000"/>
    </bean>

    <!-- 3.配置SqlSessionFactory对象 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 注入数据库连接池 -->
        <property name="dataSource" ref="dataSource"/>
        <!-- 配置MyBaties全局配置文件:mybatis-config.xml -->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>
    
    <!-- 4.配置扫描Dao接口包，动态实现Dao接口注入到spring容器中 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 注入sqlSessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!-- 给出需要扫描Dao接口包 -->
        <property name="basePackage" value="com.itcast.dao"/>
    </bean>
</beans>

mybatis-config.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <typeAliases>
        <package name="com.itcast.pojo"/>
    </typeAliases>
    <mappers>
        <mapper resource="com/itcast/dao/UserMapper.xml"/>
    </mappers>
</configuration>

database.properties:

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=root

1.5 spring-mvc.xml(Spring和SpringMVC整合):

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/mvc
    https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <!-- 1.开启SpringMVC注解驱动 -->
    <mvc:annotation-driven />
    
    <!-- 2.静态资源默认servlet配置-->
    <mvc:default-servlet-handler/>
    
    <!-- 3.配置jsp 显示ViewResolver视图解析器 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
   
    <!-- 4.扫描web相关的bean -->
    <context:component-scan base-package="com.itcast.controller" />
</beans>

1.6 spring-bean.xml(Spring配置bean)

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">
    <!-- 扫描service相关的bean -->
    <context:component-scan base-package="com.itcast.service" />
    
    <!--UserServiceImpl注入到IOC容器中-->
    <bean id="UserServiceImpl" class="com.itcast.service.UserServiceImpl">
        <property name="userMapper" ref="userMapper"/>
    </bean>
    
    <!-- 配置事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!-- 注入数据库连接池 -->
        <property name="dataSource" ref="dataSource" />
    </bean>
</beans>

1.7 user表：

create table if not exists user
(
    id       varchar(50) not null
        primary key,
    username varchar(50) null,
    password varchar(50) null
);

2.编写pojo实体类层：

package com.itcast.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private String id;
    private String username;
    private String password;
    public User(String username, String password) {
        this.username = username;
        this.password = password;
    }
}

3.编写Dao层

数据库交互层

UserMapper.class:

package com.itcast.dao;

import com.itcast.pojo.User;

public interface UserMapper {
    User getUserById(Integer id);
    User getUserByName(String name);
    void addUser(User user);
    User login(User user);
}

UserMapper.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.itcast.dao.UserMapper">
    <select id="getUserById" parameterType="int" resultType="com.itcast.pojo.User">
        select * from user where id = #{id}
    </select>
    <select id="getUserByName" parameterType="java.lang.String" resultType="com.itcast.pojo.User">
        select * from user where username = #{username}
    </select>
    <select id="login" resultType="com.itcast.pojo.User" parameterType="com.itcast.pojo.User">
        select * from user where username = #{username} and password = #{password}
    </select>
    <insert id="addUser" parameterType="com.itcast.pojo.User">
        insert into user values (#{id},#{username},#{password})
    </insert>
</mapper>

4.编写Service层：

UserService.interface

package com.itcast.service;

import com.itcast.pojo.User;
import org.springframework.ui.Model;

public interface UserService {

    User getUserById(Integer id);
    User getUserByName(String name);
    void addUser(User user);
    String login(Model model, User user);

    String register(Model model, String username, String password, String confirm);
}

UserServiceImpl.class:

package com.itcast.service;

import com.itcast.dao.UserMapper;
import com.itcast.pojo.User;
import org.springframework.ui.Model;

import java.util.UUID;

public class UserServiceImpl implements UserService{

    private UserMapper userMapper;

    public void setUserMapper(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

    /**
     * 登录
     * @param model
     * @param user
     * @return
     */
    @Override
    public String login(Model model, User user) {
        User user1 = userMapper.login(user);
        if (user1 != null){
            return "success";
        }else {
            model.addAttribute("msg", "用户名或密码错误");
            return "fail";
        }
    }

    /**
     * 注册
     * @param model
     * @param username
     * @param password
     * @param confirm
     * @return
     */
    @Override
    public String register(Model model, String username, String password, String confirm) {
        if (password.equals(confirm)){
            User user = userMapper.getUserByName(username);
            if (user == null) {
                User register = new User(username, password);
                UUID uuid = UUID.randomUUID();
                register.setId(uuid.toString());
                userMapper.addUser(register);
                return "login";
            }else {
                model.addAttribute("msg", "该用户已经注册");
                return "fail";
            }
        }else {
            model.addAttribute("msg", "两次密码不一致");
            return "fail";
        }
    }
}

6.编写Controller层：

UserController.class

package com.itcast.controller;

import com.itcast.pojo.User;
import com.itcast.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class UserController {
    @Autowired
    private UserService userService;

    @RequestMapping("/login")
    public String login(Model model, String username, String password){
        model.addAttribute("username",username);
        return userService.login(model, new User(username,password));
    }

    @RequestMapping("/register")
    public String register(Model model, String username, String password, String confirm){
        return userService.register(model, username, password, confirm);
    }

    @RequestMapping("/register_forward")
    public String forwardRegisterPage() {
        return "register";
    }
}

7.Web层界面

login.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登录</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background-color: #f4f4f9;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            margin: 0;
        }
        form {
            background-color: #fff;
            padding: 20px;
            border-radius: 5px;
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
        }
        input[type="text"], input[type="password"] {
            width: 100%;
            padding: 10px;
            margin: 10px 0;
            border: 1px solid #ccc;
            border-radius: 5px;
        }
        input[type="submit"] {
            background-color: #007bff;
            color: white;
            padding: 10px 15px;
            border: none;
            border-radius: 5px;
            cursor: pointer;
        }
        input[type="submit"]:hover {
            background-color: #0056b3;
        }
        a {
            display: block;
            text-align: center;
            margin-top: 10px;
            color: #007bff;
            text-decoration: none;
        }
        a:hover {
            text-decoration: underline;
        }
    </style>
</head>
<body>
<form action="/login" method="post">
    <div>
        <label for="username">用户名：</label>
        <input type="text" id="username" name="username" required>
    </div>
    <div>
        <label for="password">密码：</label>
        <input type="password" id="password" name="password" required>
    </div>
    <input type="submit" value="登录">
    <button onclick="window.location.href='/register_forward'">注册</button>
</form>

</body>
</html>

register.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>注册</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background-color: #f4f4f9;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            margin: 0;
        }
        form {
            background-color: #fff;
            padding: 20px;
            border-radius: 5px;
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
            width: 300px;
        }
        input[type="text"], input[type="email"], input[type="password"], input[type="confirm"] {
            width: 100%;
            padding: 10px;
            margin: 10px 0;
            border: 1px solid #ccc;
            border-radius: 5px;
        }
        input[type="submit"] {
            background-color: #28a745;
            color: white;
            padding: 10px 15px;
            border: none;
            border-radius: 5px;
            cursor: pointer;
            width: 100%;
        }
        input[type="submit"]:hover {
            background-color: #218838;
        }
        label {
            display: block;
            margin-bottom: 5px;
            font-weight: bold;
        }
    </style>
</head>
<body>
<form action="/register" method="post">
    <div>
        <label for="username">用户名：</label>
        <input type="text" id="username" name="username" required>
    </div>
    <div>
        <label for="password">密码：</label>
        <input type="password" id="password" name="password" required>
    </div>
    <div>
        <label for="confirm">确认密码：</label>
        <input type="confirm" id="confirm" name="confirm" required>
    </div>
    <input type="submit" value="注册">
</form>
</body>
</html>

fail.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Error</title>
</head>
<body>
   ${msg}
</body>
</html>

success.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Success</title>
</head>
<body>
    登录成功，${username}
</body>
</html>