1. 整合 Mybatis

• 步骤

  • 导入相关 jar 包

    <dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.47</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.2</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.1.9.RELEASE</version></dependency><!-- spring 操作数据库，需要一个 Spring-jdbc --><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>5.1.9.RELEASE</version></dependency><!-- 织入包 --><dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId><version>1.8.13</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>2.0.2</version></dependency>
    </dependencies>
    

  • 编写配置文件

  • 测试

1.1 回顾 Mybatis

• 导入依赖

• 编写实体类

  @Data
  public class User {private int id;private String name;private String pw;
  }
  

• 编写核心配置文件

  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
  <configuration><typeAliases><package name="com.why.pojo"/></typeAliases><environments default="development"><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/><property name="username" value="root"/><property name="password" value="981030"/></dataSource></environment></environments><mappers><mapper class="com.why.mapper.UserMapper"/></mappers></configuration>
  

• 编写接口

  public interface UserMapper {public List<User> selectUser();
  }
  

• 编写 Mapper.xml

  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  <mapper namespace="com.why.mapper.UserMapper"><select id="selectUser" resultType="user">select * from user ;</select></mapper>
  

• 开启资源过滤

  <build><resources><resource><directory>src/main/java</directory><includes><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources>
  </build>
  

• 测试

  public class MyTest {@Testpublic void test() throws IOException {String resources = "mybatis-config.xml";InputStream in = Resources.getResourceAsStream(resources);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);SqlSession sqlSession = sqlSessionFactory.openSession(true);UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<User> users = mapper.selectUser();for (User user : users) {System.out.println(user);}}
  }
  

1.2 什么是 MyBatis-Spring

MyBatis-Spring 会帮助你将 MyBatis 代码无缝地整合到 Spring 中。它将允许 MyBatis 参与到 Spring 的事务管理之中，创建映射器 mapper 和 SqlSession 并注入到 bean 中，以及将 Mybatis 的异常转换为 Spring 的 DataAccessException。 最终，可以做到应用代码不依赖于 MyBatis，Spring 或 MyBatis-Spring。

1.3 知识基础

在开始使用 MyBatis-Spring 之前，你需要先熟悉 Spring 和 MyBatis 这两个框架和有关它们的术语。这很重要——因为本手册中不会提供二者的基本内容，安装和配置教程。

MyBatis-Spring 需要以下版本：

MyBatis-Spring	MyBatis	Spring Framework	Spring Batch	Java
2.0	3.5+	5.0+	4.0+	Java 8+
1.3	3.4+	3.2.2+	2.1+	Java 6+

12.4 整合方式一

• 添加数据源

  

• 配置数据源（spring-dao.xml）

  <!--dataSource： 使用 Spring 的数据源替换 Mybatis 的配置此处使用 Spring 提供的 JDBC (spring-jdbc)还可以使用 C3p0 / Dbcp / Druid
  -->
  <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"><property name="driverClassName" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/><property name="username" value="root"/><property name="password" value="981030"/>
  </bean>
  

• 创建 SqlSessionFactor (spring-dao.xml)

  <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"><property name="dataSource" ref="dataSource" /><!-- 绑定 Mybatis 配置文件 --><property name="configLocation" value="classpath:mybatis-config.xml"/><property name="mapperLocations" value="classpath:com/why/mapper/*.xml"/>
  </bean>
  

• 获取 SqlSessionTemplate / SqlSession (spring-dao.xml)

  <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate"><!-- 因为没有 set 方法，只能使用构造器注入 --><constructor-arg index="0" ref="sqlSessionFactory"/>
  </bean>
  

• 创建接口的实现类【用于执行Mybatis的操作】

  public class UserMapperImpl implements UserMapper {// 使用 sqlSessionTemplate 替换 sqlSession 操作Mybatisprivate SqlSessionTemplate sqlSession;public void setSqlSession(SqlSessionTemplate sqlSession) {this.sqlSession = sqlSession;}public List<User> selectUser() {UserMapper mapper = sqlSession.getMapper(UserMapper.class);return mapper.selectUser();}
  }
  

• 将实现类注入到 Spring (applicationContext.xml)

  <bean id="userMapper" class="com.why.mapper.UserMapperImpl"><property name="sqlSession" ref="sqlSession"/>
  </bean>
  

• 测试

  public class MyTest {@Testpublic void test() throws IOException {ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");UserMapper userMapper = context.getBean("userMapper", UserMapper.class);List<User> users = userMapper.selectUser();for (User user : users) {System.out.println(user);}}
  }
  

• 目录结构

  

12.5 整合方式二

• 让实现类继承 SqlSessionDaoSupport ，此时实现类的方法中可以直接使用 getSqlSession() 方法来获取 SqlSession ，本质还是第一种方法。

  public class UserMapperImpl2 extends SqlSessionDaoSupport implements UserMapper {public List<User> selectUser() {return getSqlSession().getMapper(UserMapper.class).selectUser();}
  }
  

• XML 文件中不需要配置和注入 SqlSession 了，但是需要配置 SqlSessionFactory，SqlSessionDaoSupport 需要用 SqlSessionFactory 来获取 SqlSession。

  <bean id="userMapper" class="com.why.mapper.UserMapperImpl"><property name="sqlSessionFactory" ref="sqlSessionFactory"/>
  </bean>