Spring MVC实现一个注册登录模块

实现注册登录模块需要以下步骤：

1.创建Maven Web项目，引入Spring和Spring MVC的依赖。

2.创建数据库表，包括用户id、用户名、密码等字段。

3.创建用户实体类，并在其中定义与数据库表字段对应的属性。

4.创建用户DAO接口，并定义对用户表进行增删改查的方法。

5.创建用户Service接口，并定义注册、登录、修改密码等方法。

6.创建用户Controller，并在其中实现注册、登录等请求处理方法。

7.创建JSP页面，包括注册、登录页面等。

8.配置Spring和Spring MVC，定义数据源、事务管理器等相关配置。

下面是一个简单的示例代码：

1.创建用户实体类

public class User {
    private int id;
    private String username;
    private String password;

    // getter and setter methods
}

2.创建用户DAO接口

public interface UserDao {
    void addUser(User user);
    User getUserById(int id);
    User getUserByUsername(String username);
    void updateUser(User user);
}

3.创建用户Service接口

public interface UserService {
    void register(User user);
    User login(String username, String password);
    void changePassword(int userId, String newPassword);
}

4.创建用户Controller

@Controller
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;

    @RequestMapping(value="/register", method=RequestMethod.GET)
    public String showRegisterForm(Model model) {
        model.addAttribute("user", new User());
        return "registerForm";
    }

    @RequestMapping(value="/register", method=RequestMethod.POST)
    public String processRegisterForm(@ModelAttribute("user") User user) {
        userService.register(user);
        return "redirect:/user/login";
    }

    @RequestMapping(value="/login", method=RequestMethod.GET)
    public String showLoginForm() {
        return "loginForm";
    }

    @RequestMapping(value="/login", method=RequestMethod.POST)
    public String processLoginForm(@RequestParam("username") String username,
                                    @RequestParam("password") String password,
                                    Model model) {
        User user = userService.login(username, password);
        if (user != null) {
            model.addAttribute("user", user);
            return "home";
        } else {
            model.addAttribute("error", "Invalid username or password");
            return "loginForm";
        }
    }

    @RequestMapping(value="/changePassword", method=RequestMethod.GET)
    public String showChangePasswordForm() {
        return "changePasswordForm";
    }

    @RequestMapping(value="/changePassword", method=RequestMethod.POST)
    public String processChangePasswordForm(@RequestParam("userId") int userId,
                                            @RequestParam("newPassword") String newPassword,
                                            Model model) {
        userService.changePassword(userId, newPassword);
        model.addAttribute("success", "Password changed successfully");
        return "changePasswordForm";
    }
}

5.创建JSP页面

registerForm.jsp

<form:form method="POST" action="/user/register">
    <form:label path="username">Username:</form:label>
    <form:input path="username" />
    <form:label path="password">Password:</form:label>
    <form:password path="password" />
    <input type="submit" value="Register" />
</form:form>

loginForm.jsp

<form:form method="POST" action="/user/login">
    <form:label path="username">Username:</form:label>
    <form:input path="username" />
    <form:label path="password">Password:</form:label>
    <form:password path="password" />
    <input type="submit" value="Login" />
</form:form>

changePasswordForm.jsp

<form:form method="POST" action="/user/changePassword">
    <form:hidden path="userId" value="${user.id}" />
    <form:label path="newPassword">New password:</form:label>
    <form:password path="newPassword" />
    <input type="submit" value="Change" />
</form:form>

6.配置Spring和Spring MVC

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/mydb"/>
    <property name="username" value="root"/>
    <property name="password" value=""/>
</bean>

<bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="packagesToScan" value="com.example.entity"/>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.format_sql">true</prop>
        </props>
    </property>
</bean>

<bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>

<context:component-scan base-package="com.example"/>
<mvc:annotation-driven/>
<mvc:resources mapping="/resources/**" location="/resources/"/>
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/views/"/>
    <property name="suffix" value=".jsp"/>
</bean>