一、ContextLoaderListener

原因：SpringMVC提供控制层，负责请求和响应。Controller要调用Service，Service是由Spring IOC提供，而Controller由SpringMVC IOC提供，所以我们需要首先创建Spring IOC，然后才能获取里面的bean对象。

监听器的执行顺序先于过滤器，过滤器的执行顺序先于service。

Spring中有三种监听器：ServletContextListener，HttpSessionListener，HttpSessionAttributeListener。

ContextLoaderListener实现了ServletContextListener接口，可以监听ServletContext的状态，在web服务器的启动时读取Spring核心配置文件，创建Spring IOC容器。

配置ContextLoaderListener的位置：web.xml

<!-- 配置监听器，当服务器启动时，初始化 Spring IOC 容器 -->
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

<!-- 配置加载 Spring 配置文件的位置和名称 -->
<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:spring.xml</param-value>
</context-param>

注意：如果不配置context-param那么需要把配置文件放到指定的位置，并且名称也不能自定义，名称必须为applicationContext.xml，路径必须要是/WEB-INF/。

二、导入依赖

<properties>
    <spring.version>5.3.1</spring.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <!--springmvc-->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <!-- Mybatis核心 -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.7</version>
    </dependency>
    <!--mybatis和spring的整合包-->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis-spring</artifactId>
        <version>2.0.6</version>
    </dependency>
    <!-- 连接池 -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.0.9</version>
    </dependency>
    <!-- junit测试 -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <!-- MySQL驱动 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.16</version>
    </dependency>
    <!-- log4j日志 -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
    <dependency>
        <groupId>com.github.pagehelper</groupId>
        <artifactId>pagehelper</artifactId>
        <version>5.2.0</version>
    </dependency>
    <!-- 日志 -->
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.2.3</version>
    </dependency>
    <!-- ServletAPI -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.12.1</version>
    </dependency>
    <dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.3.1</version>
    </dependency>
    <!-- Spring5和Thymeleaf整合包 -->
    <dependency>
        <groupId>org.thymeleaf</groupId>
        <artifactId>thymeleaf-spring5</artifactId>
        <version>3.0.12.RELEASE</version>
    </dependency>
    <!-- lombok -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.24</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

三、创建表

CREATE TABLE `t_emp` (
`emp_id` int(11) NOT NULL AUTO_INCREMENT,
`emp_name` varchar(20) DEFAULT NULL,
`age` int(11) DEFAULT NULL,
`sex` char(1) DEFAULT NULL,
`email` varchar(50) DEFAULT NULL,
PRIMARY KEY (`emp_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

四、配置web.xml

使用监听器监听服务器的启动，当服务器启动时，首先会初始化监听器。

<?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">

    <!-- 配置监听器，当服务器启动时，初始化 Spring IOC 容器 -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- 配置加载 Spring 配置文件的位置和名称 -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring.xml</param-value>
    </context-param>

    <!-- 配置 SpringMVC 的编码过滤器 -->
    <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>
        <init-param>
            <param-name>forceResponseEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CharacterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- 配置处理请求方式的过滤器 -->
    <filter>
        <filter-name>HiddenHttpMethodFilter</filter-name>
        <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>HiddenHttpMethodFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- 配置 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:springmvc.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>
</web-app>

五、日志文件

log4j.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

    <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
        <param name="Encoding" value="UTF-8"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%-5d %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n"/>
        </layout>
    </appender>

    <logger name="java.sql">
        <level value="debug"/>
    </logger>
    <logger name="org.apache.ibatis" >
        <level value="info"/>
    </logger>

    <!-- 默认配置，级别为debug 且根据name为log.console和 log.file两个appender输出-->
    <root>
        <level value="debug"/>
        <appender-ref ref="STDOUT"/>
    </root>
</log4j:configuration>

六、创建jdbc.properties文件

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm_01?serverTimezone=UTC
jdbc.username=lukeewin
jdbc.password=123456

七、创建SpringMVC.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: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">

    <!-- 配置组件扫描 -->
    <context:component-scan base-package="top.lukeewin.ssm.controller"/>

    <!-- 配置 Thymeleaf 视图解析器 -->
    <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">
        <property name="order" value="1"/>
        <property name="characterEncoding" value="UTF-8"/>
        <property name="templateEngine">
            <bean class="org.thymeleaf.spring5.SpringTemplateEngine">
                <property name="templateResolver">
                    <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">
                        <!-- 视图前缀 -->
                        <property name="prefix" value="/WEB-INF/templates/"/>
                        <!-- 视图后缀 -->
                        <property name="suffix" value=".html"/>
                        <property name="templateMode" value="HTML5"/>
                        <property name="characterEncoding" value="UTF-8" />
                    </bean>
                </property>
            </bean>
        </property>
    </bean>

    <!-- 配置默认的 servlet 处理静态资源 -->
    <mvc:default-servlet-handler/>

    <!-- 开启注解驱动 -->
    <mvc:annotation-driven/>

    <!-- 配置视图控制器 -->
    <mvc:view-controller path="/" view-name="index"/>

    <!-- 配置文件上传解析器 -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"/>
</beans>

八、创建Spring.xml

SqlSessionFactoryBean会在Spring IOC容器中产生一个sqlSession对象。

MapperScannerConfigurer创建指定包下的所有接口的代理类对象，配置了它，就不需要使用sqlSession.getMapper(Employee.class)创建一个代理类了。MapperScannerConfigurer创建的代理类对象放在Spring IOC容器中，所以我们可以直接使用注解方式进行自动注入。

@Resource
private EmployeeMapper employeeMapper;
employeeMapper.getAllEmployee();
// 以前的写法
EmployeeMapper mapper = sqlSession.getMapper(Employee.class);
mapper.getAllEmployee();

id="transactionManager"可以省略transaction-manager="transactionManager"。

<?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:tx="http://www.springframework.org/schema/tx"
       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/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!-- 扫描组件（除控制层） -->
    <context:component-scan base-package="top.lukeewin.ssm">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>

    <!-- 引入 jdbc.properties 文件 -->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!-- 数据源 -->
    <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}"/>
    </bean>

    <!-- 配置事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!--
        开启事务注解驱动
        将使用注解 @Transactional 标识的方法或类中的所有方法进行事务管理
    -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

    <!-- 配置 SqlSessionFactoryBean，可以直接在 Spring IOC 中获取 SqlSessionFactory -->
    <bean class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 设置加载 MyBatis 的核心配置文件的路径 -->
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <!-- 设置数据源 -->
        <property name="dataSource" ref="dataSource"/>
        <!-- 设置类型别名所对应的包 -->
        <property name="typeAliasesPackage" value="top.lukeewin.ssm.pojo"/>
        <!-- 设置映射文件的路径，只有映射的包和 mapper 接口的包不一致时才需要设置 -->
        <!--<property name="mapperLocations" value="classpath:mappers/*.xml"/>-->
    </bean>

    <!--
        配置 mapper 接口的扫描，可以将指定包下的所有 mapper 接口
        通过 SqlSession 创建的代理实现类对象，并将这些对象交给 IOC 容器管理
    -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="top.lukeewin.ssm.mapper"/>
    </bean>
</beans>

九、创建mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <!--
        MyBatis核心配置文件中的标签必须要按照指定的顺序配置
        properties?,settings?,typeAliases?,typeHandlers?,
        objectFactory?,objectWrapperFactory?,reflectorFactory?,
        plugins?,environments?,databaseIdProvider?,mappers?
    -->

    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>

    <!-- 配置分页插件 -->
    <plugins>
        <plugin interceptor="com.github.pagehelper.PageInterceptor"/>
    </plugins>
</configuration>

十、分页显示数据

pageNum：当前页的页码

pageSize：每页显示的条数

size：当前页显示的真实条数

total：总记录数

pages：总页数

prePage：上一页

nextPage：下一页

isFirstPage/isLastPage：是否为第一页/是否为最后一页

hasPreviousPage/hasNextPage：是否存在上一页/下一页

navigatePages：导航分页的页码数

navigatepageNums：导航分页的页码，[1,2,3,4,5]

list：存储从数据库中获取过来的数据

Controller

@Override
public PageInfo<Employee> getEmployeePage(Integer pageNum) {
    // 开启分页功能
    PageHelper.startPage(pageNum, 4);
    List<Employee> list = employeeMapper.getAllEmployee();
    // 获取分页相关数据
    PageInfo<Employee> page = new PageInfo<>(list, 5);
    return page;
}

Service

开始分页

@Override
public PageInfo<Employee> getEmployeePage(Integer pageNum) {
    // 开启分页功能
    PageHelper.startPage(pageNum, 4);
    List<Employee> list = employeeMapper.getAllEmployee();
    // 获取分页相关数据
    PageInfo<Employee> page = new PageInfo<>(list, 5);
    return page;
}

前端

展示数据

<table>
    <tr>
        <th colspan="6">员工列表</th>
    </tr>
    <tr>
        <th>序号</th>
        <th>员工姓名</th>
        <th>年龄</th>
        <th>性别</th>
        <th>邮箱</th>
        <th>操作</th>
    </tr>
    <tr th:each="employee,status : ${page.list}">
        <td th:text="${status.count}"></td>
        <td th:text="${employee.empName}"></td>
        <td th:text="${employee.age}"></td>
        <td th:text="${employee.sex}"></td>
        <td th:text="${employee.email}"></td>
        <td>
            <a href="">删除</a>
            <a href="">修改</a>
        </td>
    </tr>
</table>

前端

添加页面跳转

<div style="text-align: center">
    <a th:if="${page.hasPreviousPage}" th:href="@{/employee/page/1}">首页</a>
    <a th:if="${page.hasPreviousPage}" th:href="@{'/employee/page/' + ${page.prePage}}">上一页</a>
    <span th:each="num : ${page.navigatepageNums}">
        <a th:if="${page.pageNum == num}" style="color: red" th:href="@{'/employee/page/' + ${num}}" th:text="'[' + ${num} + ']'"></a>
        <a th:if="${page.pageNum != num}" th:href="@{'/employee/page/' + ${num}}" th:text="${num}"></a>
    </span>
    <a th:if="${page.hasNextPage}" th:href="@{'/employee/page/' + ${page.nextPage}}">下一页</a>
    <a th:if="${page.hasNextPage}" th:href="@{'/employee/page/' + ${page.pages}}">尾页</a>
</div>

Q.E.D.