SSM 框架整合

基本依赖

1. 相关 Jar 包

   • Jackson
   • Spring、SpringMVC、Spring JDBC
   • mybatis、mybatis-spring
   • druid 连接池

2. 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

1. 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>
   

2. 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>
   

3. 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

1. UserMapper

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

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

2. 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();
       }
   }
   

3. 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();
       }
   }
   

4. 实体类

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

5. 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

1. 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[]{"/"};
       }
   }
   

2. 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/");
       }
   }