springboot(七)：springboot+mybatis多数据源最简解决方案

傷城~ 2022-03-25 01:16 124阅读 0赞

说起多数据源，一般都来解决那些问题呢，主从模式或者业务比较复杂需要连接不同的分库来支持业务。我们项目是后者的模式，网上找了很多，大都是根据jpa来做多数据源解决方案，要不就是老的spring多数据源解决方案，还有的是利用aop动态切换，感觉有点小复杂，其实我只是想找一个简单的多数据支持而已，折腾了两个小时整理出来，供大家参考。

> 废话不多说直接上代码吧

## 配置文件 ##

pom包就不贴了比较简单该依赖的就依赖，主要是数据库这边的配置：

mybatis.config-locations=classpath:mybatis/mybatis-config.xml
    
    spring.datasource.test1.driverClassName = com.mysql.jdbc.Driver
    spring.datasource.test1.url = jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8
    spring.datasource.test1.username = root
    spring.datasource.test1.password = root
    
    spring.datasource.test2.driverClassName = com.mysql.jdbc.Driver
    spring.datasource.test2.url = jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=utf-8
    spring.datasource.test2.username = root
    spring.datasource.test2.password = root

一个test1库和一个test2库，其中test1位主库，在使用的过程中必须指定主库，不然会报错。

## 数据源配置 ##

@Configuration
    @MapperScan(basePackages = "com.neo.mapper.test1", sqlSessionTemplateRef  = "test1SqlSessionTemplate")
    public class DataSource1Config {
    
        @Bean(name = "test1DataSource")
        @ConfigurationProperties(prefix = "spring.datasource.test1")
        @Primary
        public DataSource testDataSource() {
            return DataSourceBuilder.create().build();
        }
    
        @Bean(name = "test1SqlSessionFactory")
        @Primary
        public SqlSessionFactory testSqlSessionFactory(@Qualifier("test1DataSource") DataSource dataSource) throws Exception {
            SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
            bean.setDataSource(dataSource);
            bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mybatis/mapper/test1/*.xml"));
            return bean.getObject();
        }
    
        @Bean(name = "test1TransactionManager")
        @Primary
        public DataSourceTransactionManager testTransactionManager(@Qualifier("test1DataSource") DataSource dataSource) {
            return new DataSourceTransactionManager(dataSource);
        }
    
        @Bean(name = "test1SqlSessionTemplate")
        @Primary
        public SqlSessionTemplate testSqlSessionTemplate(@Qualifier("test1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
            return new SqlSessionTemplate(sqlSessionFactory);
        }
    
    }

最关键的地方就是这块了，一层一层注入,首先创建DataSource，然后创建SqlSessionFactory再创建事务，最后包装到SqlSessionTemplate中。其中需要指定分库的mapper文件地址，以及分库dao层代码

@MapperScan(basePackages = "com.neo.mapper.test1", sqlSessionTemplateRef  = "test1SqlSessionTemplate")

这块的注解就是指明了扫描dao层，并且给dao层注入指定的SqlSessionTemplate。所有`@Bean`都需要按照命名指定正确。

## dao层和xml层 ##

dao层和xml需要按照库来分在不同的目录，比如：test1库dao层在com.neo.mapper.test1包下，test2库在com.neo.mapper.test1

public interface User1Mapper {
    	
    	List<UserEntity> getAll();
    	
    	UserEntity getOne(Long id);
    
    	void insert(UserEntity user);
    
    	void update(UserEntity user);
    
    	void delete(Long id);
    
    }

xml层

<?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" >
    <mapper namespace="com.neo.mapper.test1.User1Mapper" >
        <resultMap id="BaseResultMap" type="com.neo.entity.UserEntity" >
            <id column="id" property="id" jdbcType="BIGINT" />
            <result column="userName" property="userName" jdbcType="VARCHAR" />
            <result column="passWord" property="passWord" jdbcType="VARCHAR" />
            <result column="user_sex" property="userSex" javaType="com.neo.enums.UserSexEnum"/>
            <result column="nick_name" property="nickName" jdbcType="VARCHAR" />
        </resultMap>
        
        <sql id="Base_Column_List" >
            id, userName, passWord, user_sex, nick_name
        </sql>
    
        <select id="getAll" resultMap="BaseResultMap"  >
           SELECT 
           <include refid="Base_Column_List" />
    	   FROM users
        </select>
    
        <select id="getOne" parameterType="java.lang.Long" resultMap="BaseResultMap" >
            SELECT 
           <include refid="Base_Column_List" />
    	   FROM users
    	   WHERE id = #{id}
        </select>
    
        <insert id="insert" parameterType="com.neo.entity.UserEntity" >
           INSERT INTO 
           		users
           		(userName,passWord,user_sex) 
           	VALUES
           		(#{userName}, #{passWord}, #{userSex})
        </insert>
        
        <update id="update" parameterType="com.neo.entity.UserEntity" >
           UPDATE 
           		users 
           SET 
           	<if test="userName != null">userName = #{userName},</if>
           	<if test="passWord != null">passWord = #{passWord},</if>
           	nick_name = #{nickName}
           WHERE 
           		id = #{id}
        </update>
        
        <delete id="delete" parameterType="java.lang.Long" >
           DELETE FROM
           		 users 
           WHERE 
           		 id =#{id}
        </delete>
    
    </mapper>

## 测试 ##

测试可以使用SpringBootTest,也可以放到Controller中，这里只贴Controller层的使用

@RestController
    public class UserController {
    
        @Autowired
        private User1Mapper user1Mapper;
    
    	@Autowired
    	private User2Mapper user2Mapper;
    	
    	@RequestMapping("/getUsers")
    	public List<UserEntity> getUsers() {
    		List<UserEntity> users=user1Mapper.getAll();
    		return users;
    	}
    	
        @RequestMapping("/getUser")
        public UserEntity getUser(Long id) {
        	UserEntity user=user2Mapper.getOne(id);
            return user;
        }
        
        @RequestMapping("/add")
        public void save(UserEntity user) {
            user2Mapper.insert(user);
        }
        
        @RequestMapping(value="update")
        public void update(UserEntity user) {
            user2Mapper.update(user);
        }
        
        @RequestMapping(value="/delete/{id}")
        public void delete(@PathVariable("id") Long id) {
            user1Mapper.delete(id);
        }
        
    }

**[示例代码-github][-github]**

**[示例代码-码云][-]**

[-github]: https://github.com/ityouknow/spring-boot-examples
[-]: https://gitee.com/ityouknow/spring-boot-examples