SSM 框架整合本文介绍 Spring + SpringMVC + MyBatis 框架的整合，提供 XML 配置和 J

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基本依赖

相关 Jar 包
- Jackson
- Spring、SpringMVC、Spring JDBC
- mybatis、mybatis-spring
- druid 连接池

pom.xml

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.2.8.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>5.2.8.RELEASE</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.11.2</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.21</version>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.4.6</version>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>1.3.2</version>
</dependency>
<dependency>
    <groupId>commons-logging</groupId>
    <artifactId>commons-logging</artifactId>
    <version>1.2</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.2.4</version>
</dependency>

使用 XML 配置

web.xml 配置

配置 DispatcherServlet 并设置启动加载

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         id="WebApp_ID" version="3.1">
    <servlet>
        <servlet-name>app</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>app</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

spring-config.xml

配置 MyBatis、数据源、MapperSanner

<?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-4.0.xsd
         http://www.springframework.org/schema/context
         http://www.springframework.org/schema/context/spring-context-4.0.xsd
         http://www.springframework.org/schema/mvc
         http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">
    <!--配置 MyBatis-->
    <bean id="sqlSessionFactory"
          class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <!--mybatis 配置文件-->
        <property name="configLocation"
                  value="classpath:mybatis-config.xml" />
        <!--mapper.xml 存放位置-->
        <property name="mapperLocations"
                  value="classpath:mapper/*.xml" />
    </bean>
    <!--配置数据源-->
    <!--读取 db.properties-->
    <context:property-placeholder location="classpath:db.properties" />
    <bean id="dataSource"
          class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName"
                  value="${mysql.driver}" />
        <property name="url"
                  value="${mysql.url}" />
        <property name="username" value="${mysql.username}" />
        <property name="password" value="${mysql.password}" />
    </bean>
    <!--配置 MapperScanner-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="sqlSessionFactoryBeanName"
                  value="sqlSessionFactory" />
        <!--@Mapper 扫描包-->
        <property name="basePackage" value="cade.mapper" />
    </bean>
    <!--配置 component 扫描-->
    <context:component-scan
            base-package="cade.controller" />
    <context:component-scan
            base-package="cade.service" />
    <!--配置 mvc 注解支持-->
    <mvc:annotation-driven />
     <!--配置静态资源映射-->
    <mvc:resources mapping="/static/**" location="classpath:static/" />
</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>
    <!--别名配置-->
    <typeAliases>
        <package name="cade.entity" />
    </typeAliases>
</configuration>

编写测试代码

UserMapper

@Mapper
public interface UserMapper {
    List<User> listUsersAll();
}

<mapper namespace="cade.mapper.UserMapper">
    <select id="listUsersAll" resultType="user">
        select * from user
    </select>
</mapper>

UserService

@Service
public class UserServiceImpl implements UserService {

    private final UserMapper userMapper;

    @Autowired
    public UserServiceImpl(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

    @Override
    public List<User> listUsersAll() {
        return userMapper.listUsersAll();
    }
}

UserController

@Controller
public class HelloController {

    private final UserService userService;

    @Autowired
    public HelloController(UserService userService) {
        this.userService = userService;
    }

    @ResponseBody
    @RequestMapping("/users")
    public List<User> listUsersAll() {
        return userService.listUsersAll();
    }
}

实体类

public class User {
    String name;
    Integer age;
	// ...
}

访问 /users 进行测试

[{"name":"李四","age":20},{"name":"张三","age":23},{"name":"王五","age":23}]

使用 JavaConfig 配置

配置类代替 web.xml

在 Servlet 3.0 环境下，Servlet 容器会在 classpath 下搜索实现了 javax.servlet.ServletContainerInitializer 接口的任何类，找到之后用它来初始化 Servlet 容器

Spring 实现了以上接口，实现类叫做 SpringServletContainerInitializer，它会依次搜寻实现了 WebApplicationInitializer的任何类，并委派这个类实现配置

之后，Spring 3.2 开始引入一个简易的 WebApplicationInitializer 实现类，这就是 AbstractAnnotationConfigDispatcherServletInitializer

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return null;
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        // 引入 spring config 配置类
        return new Class[]{SpringConfig.class};
    }

    @Override
    protected String[] getServletMappings() {
        // 拦截路径
        return new String[]{"/"};
    }
}

配置类代替 spring-config.xml、mybatis.xml

在 Spring 配置类中使用注解开启 SpringMVC、配置 bean

@Configuration
@ComponentScan(basePackages = {"cade.controller", "cade.service"}) // 扫描 component
@EnableWebMvc // <mvc:annotation-driven />
public class SpringConfig implements WebMvcConfigurer {

    // mybatis
    @Bean
    public SqlSessionFactoryBean sqlSessionFactory() {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(this.dataSource());
        // mybatis 配置文件位置
        Resource mybatisConfigResource = new ClassPathResource("mybatis-config.xml");
        sqlSessionFactoryBean.setConfigLocation(mybatisConfigResource);
        // mapper.xml 文件位置
        Resource userMapperXML = new ClassPathResource("mapper/UserMapper.xml");
        sqlSessionFactoryBean.setMapperLocations(new Resource[]{userMapperXML});
        return sqlSessionFactoryBean;
    }

    // 数据源
    @Bean
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://127.0.0.1:3306/demo?useSSL=true&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai");
        dataSource.setUsername("root");
        dataSource.setPassword("cade");
        return dataSource;
    }

    // Mapper 类扫描，和 @MapperScan 功能相同
    @Bean
    public MapperScannerConfigurer initMapperScannerConfigurer() {
        MapperScannerConfigurer msc = new MapperScannerConfigurer();
        msc.setSqlSessionFactoryBeanName("sqlSessionFactory");
        msc.setBasePackage("cade.mapper");
        return msc;
    }

    // <mvc:resources mapping="/static/**" location="classpath:static/" />
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("/static/");
    }
}