整合MyBatis

摘要：本文学习了如何在Spring框架中整合MyBatis框架。

环境

Windows 10 企业版 LTSC 21H2
MySQL 5.7.40
Java 1.8
Tomcat 8.5.50
Maven 3.6.3
Spring 5.2.25.RELEASE
MyBatis 3.5.6

1 概述

分工：

Spring是核心容器，负责对象管理、依赖注入、事务控制等核心功能。
MyBatis是持久层框架，负责数据访问、持久化等功能。

整合后可以让Spring管理MyBatis的对象，并通过依赖注入的方式使用MyBatis的功能。

2 目录结构

目录结构如下：

code

demo-ssm/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/example/
│   │   │       ├── config/
│   │   │       │   ├── RootConfig.java
│   │   │       ├── entity/
│   │   │       │   └── User.java
│   │   │       ├── mapper/
│   │   │       │   ├── UserMapper.java
│   │   │       │   └── UserMapper.xml
│   │   │       ├── service/
│   │   │       │   └── UserService.java
│   │   │       └── DemoApplication.java
│   │   └── resources/
│   │       └── jdbc.properties
└── pom.xml

3 创建配置文件

创建Maven项目，并创建pom.xml文件：

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.example</groupId>
  <artifactId>demo-spring-mybatis</artifactId>
  <version>1.0.0-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.source>1.8</maven.compiler.source>
  </properties>

  <dependencies>
    <!-- Spring Context -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.2.25.RELEASE</version>
    </dependency>
    <!-- Spring JDBC -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.2.25.RELEASE</version>
    </dependency>
    <!-- MyBatis -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.13</version>
    </dependency>
    <!-- MyBatis-Spring -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.1.1</version>
    </dependency>
    <!-- MySQL -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.49</version>
    </dependency>
    <!-- Druid -->
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.2.8</version>
    </dependency>
  </dependencies>

  <build>
    <resources>
      <!-- 保留默认的资源目录 -->
      <resource>
        <directory>src/main/resources</directory>
      </resource>
      <!-- 额外添加XML文件 -->
      <resource>
        <directory>src/main/java</directory>
        <includes>
          <include>**/*.xml</include>
        </includes>
        <!-- 禁止Maven替换XML中的占位符，交由MyBatis处理 -->
        <filtering>false</filtering>
      </resource>
    </resources>
  </build>
</project>

创建jdbc.properties文件：

jdbc.properties

jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/test?useSSL=false&serverTimezone=GMT%2B8
jdbc.username=root
jdbc.password=123456

4 创建配置类

创建根容器配置类：

java

@Configuration
@EnableTransactionManagement
@PropertySource("classpath:jdbc.properties")
@MapperScan("com.example.mapper")
@ComponentScan(
        basePackages = "com.example",
        excludeFilters = @ComponentScan.Filter(type = FilterType.ANNOTATION, value = Controller.class)
)
public class RootConfig {
    @Resource
    private Environment env;
    // 配置数据连接
    @Bean
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(env.getProperty("jdbc.driverClass"));
        dataSource.setUrl(env.getProperty("jdbc.url"));
        dataSource.setUsername(env.getProperty("jdbc.username"));
        dataSource.setPassword(env.getProperty("jdbc.password"));
        return dataSource;
    }
    // 配置会话工厂
    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        // 创建会话工厂
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        // 设置数据源
        factoryBean.setDataSource(dataSource());
        // 设置映射文件路径
        factoryBean.setMapperLocations(new ClassPathResource("com/example/mapper/UserMapper.xml"));
        // 返回会话工厂
        return factoryBean.getObject();
    }
    // 配置会话模板
    @Bean
    public SqlSessionTemplate sqlSessionTemplate() throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory());
    }
    // 配置事务管理器
    @Bean
    public PlatformTransactionManager transactionManager() {
        return new DataSourceTransactionManager(dataSource());
    }
    // 配置事务模板
    @Bean
    public TransactionTemplate transactionTemplate() {
        return new TransactionTemplate(transactionManager());
    }
}

5 创建业务类

创建User类：

java

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

创建UserMapper接口：

java

1
2
3

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

创建UserMapper映射文件：

UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 指定接口全类名 -->
<mapper namespace="com.example.mapper.UserMapper">
  <!-- 配置SQL语句 -->
  <select id="selectUserList" resultType="com.example.entity.User">
    SELECT * FROM user
  </select>
</mapper>

创建UserService类：

java

@Service
@Transactional
public class UserService {
    @Resource
    private UserMapper userMapper;
    public List<User> findUserList() {
        return userMapper.selectUserList();
    }
}

创建启动类：

java

public class DemoApplication {
    public static void main(String[] args) {
        // 加载配置类
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(RootConfig.class);
        // 获取UserService对象
        UserService userService = context.getBean(UserService.class);
        // 执行查询
        List<User> userList = userService.findUserList();
        // 打印结果
        userList.forEach(System.out::println);
        // 关闭容器
        context.close();
    }
}