springmvc

说明

• 本篇开始学习springmvc的知识
• win10,idea社区版本,java1.8

SpringMVC

• Spring MVC 本身就是 Spring 框架的一部分，可以说和 Spring 框架是无缝集成。性能方面具有先天的优越性，是当今业界最主流的 Web 开发框架

MVC

• 控制层（Controller）：负责接收并转发请求，对请求进行处理后，指定视图并将响应结果发送给客户端。
• 视图层（View）：负责格式化数据并把它们呈现给用户，包括数据展示、用户交互、数据验证、界面设计等功能。
• 数据模型层（Model）：模型对象拥有最多的处理任务，是应用程序的主体部分，它负责数据逻辑（业务规则）的处理和实现数据操作（即在数据库中存取数据）

执行流程

实例

• 依赖文件如下

    <packaging>war</packaging>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <spring.version>5.2.16.RELEASE</spring.version>

    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.13</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
        </dependency>
        <!-- Spring Test -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
            <scope>test</scope>
        </dependency>
        <!-- servlet api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
  
</project>

将pom.xml中的package改为war，加入springMVC，就是web工程

war 这里默认是pom，我改成了war，经过测试没有区别

• 在src->main下新建webapp目录

• 在webapp下新建WEB-INF目录，WEB-INF下新建web.xml文件

<?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">

    <!--编码过滤器,解决post乱码问题-->
    <filter>
        <filter-name>characterEncodingFilter</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>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <servlet>
        <!--中央控制器，用于处理请求-->
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath*:spring-mvc.xml</param-value>
        </init-param>
        <!--启动级别 1 表示服务器启动，这个项目也跟着启动-->
        <load-on-startup>1</load-on-startup>
    </servlet>


    <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <!--，所有的请求都需要通过DispatcherServlet -->
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!-- 启用Spring的Session -->
    <listener>
        <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>

</web-app>

发现报错：URI is not registered (Settings | Languages & Frameworks | Schemas and DTDs)

在idea中按照报错的步骤把http://xmlns.jcp.org/xml/ns/javaee 加入进去即可

• 上方的配置文件，需要加载spring的配置文件，在resources下新建spring-mvc.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       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
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    <!--扫包，spring可以识别此包以及子包下的类中的spring相关注解,比如Service,Controller，Component等-->
    <context:component-scan base-package="xyz.shi" />
    <!-- 配置@controller扫描包 -->
    <!--<context:component-scan base-package="cn.book.controller" />-->
    <context:annotation-config/>
    <!-- 配置注解驱动，相当于同时使用最新处理器映射跟处理器适配器,对json数据响应提供支持 -->
    <mvc:annotation-driven enable-matrix-variables="true"/>
    <!--对webapp下的静态文件放行，不去走中央控制器-->
    <mvc:default-servlet-handler />

    <!-- 配置数据源 -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/test?characterEncoding=utf8&amp;allowMultiQueries=true&amp;serverTimezone=UTC"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    </bean>
    <!-- 配置jdbc -->

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource" />
    </bean>
    <!-- 配置事务管理器 -->
<!--    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">-->
<!--        <property name="dataSource" ref="dataSource"/>-->
<!--    </bean>-->
    <!-- 配置视图解析器 -->
    <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>
    <!--    配置拦截器-->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/users/**"/>
            <bean class="xyz.shi.interceptor.LoginInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

</beans>

• dao层

public interface UserDao {
    boolean login(User user);
    void save(User user);
    void delete(int id);
    void update(User user);
    User findById(int id);
    List<User> findAll();
}

• 实现dao，这里就是和数据库直接对接

@Repository
public class UserDaoImpl implements UserDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;
    @Override
    public boolean login(User user) {
        String sql = "SELECT * FROM users WHERE name = ? AND password = ?";
        List<User> users = jdbcTemplate.query(sql, new Object[]{user.getName(), user.getPassword()},
                BeanPropertyRowMapper.newInstance(User.class));
        if (!users.isEmpty()) {
            return true;
        } else {
            return false;
        }
    }

    @Override
    public void save(User user) {
        String sql = "INSERT INTO users (name, password) VALUES (?, ?)";
        jdbcTemplate.update(sql, user.getName(), user.getPassword());
    }

    @Override
    public void delete(int id) {
        String sql = "DELETE FROM users WHERE id = ?";
        jdbcTemplate.update(sql, id);
    }

    @Override
    public void update(User user) {
        String sql ="update `users` set name = ?,password = ? where id = ? ";
        jdbcTemplate.update(sql, user.getName(), user.getPassword(), user.getId());
    }

    @Override
    public User findById(int id) {
        String sql = "SELECT * FROM users WHERE id = ?";
        return jdbcTemplate.queryForObject(sql, new Object[]{id},
                BeanPropertyRowMapper.newInstance(User.class));
    }

    @Override
    public List<User> findAll() {
        String sql = "SELECT * FROM users";
        // 查询数据
        List<User> userList = jdbcTemplate.query(sql, BeanPropertyRowMapper.newInstance(User.class));
        return userList;
    }
}

• service层

public interface UserService {
    boolean login(User user);
    void save(User user);
    void delete(int id);
    void update(User user);
    User findById(int id);
    List<User> findAll();
}

• 实现service，这里主要作用实现service层的接口，具体数据逻辑是调用的userdao层，而userdao自动关联到了他的实现层也就是UserDaoImpl

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserDao userDao;
    @Override
    public boolean login(User user) {
        return userDao.login(user);
    }
    @Override
    public void save(User user) {
        userDao.save(user);
    }
    @Override
    public void delete(int id) {
        userDao.delete(id);
    }
    @Override
    public void update(User user) {
       userDao.update(user);
    }
    @Override
    public User findById(int id) {
        return userDao.findById(id);
    }
    @Override
    public List<User> findAll() {
        return userDao.findAll();
    }
}

• Controller层的登录 主要用来处理登录和注销

@Controller
@SessionAttributes("username")
@RequestMapping("/home")
public class LoginController {
    @Autowired
    private UserDao userDao;

    @GetMapping("/userlogin")
    public String userlogin() {
        return "userlogin";
    }

    @PostMapping("/login")
    public String login(@RequestParam String username, @RequestParam String password,Model model,HttpServletRequest request) {
        User user1 = new User();
        user1.setName(username);
        user1.setPassword(password);
        boolean flag = userDao.login(user1);
        if (!flag) {
            model.addAttribute("error", "用户名或密码错误");
            System.out.println("用户名或密码错误");
            // 页面路径
//            return "/WEB-INF/view/user/add.jsp";
            return "userlogin";
        }
//        model.addAttribute("username", username);
        //将用户信息放入 session 中
        request.getSession(true).setAttribute("username",username);
        System.out.println("登录成功"+ username);

        return "redirect:/users/list";
    }

    @GetMapping("/logout")
    public String logout(HttpSession session,SessionStatus sessionStatus) {
        session.removeAttribute("username");
        sessionStatus.setComplete();
        System.out.println("注销成功");
        System.out.println(session.getAttribute("username"));
        return "redirect:userlogin";
    }
}

• Controller层的UserController 主要用来处理登录后对用户进行增删改查

@Controller
@RequestMapping("/users")
public class UserController {
    @Autowired
    private UserDao userDao;


    @GetMapping("/list")
    public String list(Model model) {

        List<User> users = userDao.findAll();
        model.addAttribute("users", users);
        return "userList";
    }
    @GetMapping("/addPage")
    public String addPage(Model model) {
        return "useradd";
    }
    @PostMapping("/add")
    public String add(@RequestParam String username, @RequestParam String password, Model model) {
        User user = new User();
        user.setName(username);
        user.setPassword(password);
        userDao.save(user);
        System.out.println("添加用户信息成功");
        return "redirect:/users/list";
    }
    @GetMapping("/findPage")
    public String findPage(@RequestParam Integer id ,Model model) {
        User user = userDao.findById(id);
        if (user!=null) {
            model.addAttribute("user", user);
        } else {
            System.out.println("用户信息不存在");
        }
        return "useredit";
    }
    @PostMapping("/update")
    public String update(@RequestParam Integer id ,@RequestParam String username, @RequestParam String password) {
        User user = new User();
        user.setId(id);
        user.setPassword(password);
        user.setName(username);
        userDao.update(user);
        System.out.println("更新成功");
        return "redirect:/users/list";
    }
    @GetMapping("/del")
    public String del(@RequestParam Integer id) {
        userDao.delete(id);
        System.out.println("删除成功");
        return "redirect:/users/list";

    }

• LoginInterceptor 主要是对没有登录的进行拦截，自动跳转到登录界面

package xyz.shi.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        HttpSession session = request.getSession();
        // 检查用户是否已登录，如果未登录则跳转到登录页
        if (session.getAttribute("username") == null) {
            response.sendRedirect(request.getContextPath() + "/home/userlogin");
            return false;
        } else {
            return true;
        }
    }
}

• jsp界面，路径在/WEB-INF/jsp/目录下

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>登录</title>
</head>
<body>
    <h1>登录</h1>
    <form  action="${pageContext.request.contextPath}/home/login" method="post">
        <label for="username">用户名：</label>
        <input type="text" id="username" name="username" required><br><br>
        <label for="password">密码：</label>
        <input type="password" id="password" name="password" required><br><br>
        <input type="submit" value="登录">
    </form>
</body>
</html>

• 本地安装tomcat，我的版本为9.0.83，然后idea中装插件Smart tomcat，然后在webapp上右键运行

• 测试页面

• 源代码