1.功能介紹
在實際的開發中，同一個項目中使用多個數據源是很常見的場景。最近在學習的過程中使用注解的方式實現了一個Springboot項目多數據源的功能。具體實現方式如下。
2.在application.properties中添加多數據源配置
添加多個數據源和mapper文件路徑配置，此配置用於基於java的配置數據源中使用。
#數據庫配置
spring.datasource.demo.user.url=jdbc:mysql://xxx.xx.xx.xx:3306/demo-user
spring.datasource.demo.user.username=xxxx
spring.datasource.demo.user.password=xxxx
spring.datasource.demo.user.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.demo.server.url=jdbc:mysql://xxx.xx.xx.xx:3306/springbootdemo
spring.datasource.demo.server.username=xxxx
spring.datasource.demo.server.password=xxxx
spring.datasource.demo.server.driver-class-name=com.mysql.jdbc.Driver
#mapper文件的路徑
mybatis.demo.server.mapper-location=classpath*:mapper/demo-server/*.xml
mybatis.demo.user.mapper-location=classpath*:mapper/demo-user/*.xml
3.基於java的方式實現數據庫配置
配置類圖如下：
其中DemoUserDbConfig類源代碼如下：
其中Configuration注解表識此類為Spring的配置類。
MapperScan注解中的basePackages、annotationClass、sqlSessionTemplateRef用於配置此數據庫鏈接掃描com.example包中所有注解為DemoUserMapper的接口。
@Configuration
@MapperScan(basePackages = {"com.example"},annotationClass = DemoUserMapper.class,
sqlSessionTemplateRef = "demoUserTemplate")
public class DemoUserDbConfig extends AbstractDbConfig {
@Value("${spring.datasource.demo.user.url}")
private String url;
@Value("${spring.datasource.demo.user.username}")
private String userName;
@Value("${spring.datasource.demo.user.password}")
private String password;
@Value("${spring.datasource.demo.user.driver-class-name}")
private String driveClassName;
@Value(value = "${mybatis.demo.user.mapper-location}")
private String mapperLocation;
@Bean(name = "demoUser")
public DataSource secondaryDataSource() {
return dataSourceFactory(driveClassName, url, userName, password);
}
@Bean(name = "demoUserTemplate")
public SqlSessionTemplate demoUserSqlTemplate() throws Exception {
return new SqlSessionTemplate((sqlSessionFactory(secondaryDataSource(), mapperLocation)));
}
@Bean
@Qualifier("demoUserTransaction")
public PlatformTransactionManager demoUserTransaction() {
return new DataSourceTransactionManager(secondaryDataSource());
}
}
其中AbstractDatasource設置了通用的方法，源代碼如下：
public abstract class AbstractDbConfig {
protected SqlSessionFactory sqlSessionFactory(DataSource dataSource, String mapperLocation) throws Exception {
SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
factoryBean.setDataSource(dataSource);
ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
Resource[] resource= resourceResolver.getResources(mapperLocation);
factoryBean.setMapperLocations(resource);
return factoryBean.getObject();
}
protected DataSource dataSourceFactory(String driveClassName, String url, String userName, String password){
DruidDataSource datasource = new DruidDataSource();
datasource.setDriverClassName(driveClassName);
datasource.setUrl(url);
datasource.setUsername(userName);
datasource.setPassword(password);
datasource.setMaxActive(20);
datasource.setInitialSize(20);
return datasource;
}
}
使用相同的方法定義其他數據源。
4.定義接口和mapper文件
分別定義連接demo-user數據庫和springbootdemo數據庫的mapper文件。連接demo-user數據庫的接口如下，使用DemoUserMapper注解表識。
@DemoUserMapper
public interface UserDao {
/**
* 返回所有的dictionary列表
*
* @return 所有的dictionary列表
*/
List<String> list();
}
mapper文件如下：
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.example.multidatasource.business.user.UserDao">
<select id="list" resultType="string">
SELECT `name` FROM `user`
</select>
</mapper>
定義讀取springbootdemo數據庫的接口，代碼如下。使用DemoServerMapper注解表識
@DemoServerMapper
public interface DictionaryDao {
/**
* 返回所有的dictionary列表
*
* @return 所有的dictionary列表
*/
List<Dictionary> list();
/**
* 查詢此key下的所有子節點
*
* @param key 數據字典key
* @return 返回key所有的子節點列表
*/
List<Dictionary> listChildrenByKey(String key);
/**
* 插入數據到數據庫
*
* @param dictionary
*/
void insert(Dictionary dictionary);
}
mapper文件代碼如下：
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.example.multidatasource.business.dictionary.dao.DictionaryDao">
<resultMap id="DictionaryResultMap" type="com.example.multidatasource.business.dictionary.Dictionary">
<result property="id" column="id"></result>
<result property="dictKey" column="dict_key"></result>
<result property="dictValue" column="dict_value"></result>
<result property="parentId" column="parent_id"></result>
<result property="description" column="description"></result>
</resultMap>
<select id="list" resultMap="DictionaryResultMap">
SELECT * FROM `dictionary`
</select>
<select id="listChildrenByKey" resultMap="DictionaryResultMap">
SELECT * FROM dictionary where parent_id= (select id from dictionary where dict_key= #{key})
</select>
<delete id="delete" parameterType="int">
delete from dictionary where id = #{id}
</delete>
<insert id="insert" parameterType="com.example.multidatasource.business.dictionary.Dictionary">
INSERT INTO `dictionary`(`dict_key`,`dict_value`,`parent_id`,`description`)
VALUES(#{dictKey}, #{dictValue}, #{parentId}, #{description})
</insert>
</mapper>
5.定義注解
定義DemoUserMapper和DemoServerMapper注解，分別作為使用demo-user和springbootdemo數據庫的表識。
定義代碼如下：
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Component
@Mapper
public @interface DemoServerMapper {
/**
* The value may indicate a suggestion for a logical component name,
* to be turned into a Spring bean in case of an autodetected component.
* @return the suggested component name, if any (or empty String otherwise)
*/
String value() default "";
}
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Component
@Mapper
public @interface DemoUserMapper {
/**
* The value may indicate a suggestion for a logical component name,
* to be turned into a Spring bean in case of an autodetected component.
* @return the suggested component name, if any (or empty String otherwise)
*/
String value() default "";
}
6.使用單元測試驗證配置
編寫單元測試代碼如下：
@RunWith(SpringRunner.class)
@SpringBootTest
public class MultiDatasourceApplicationTests {
@Autowired
private DictionaryDao dictionaryDao;
@Autowired
private UserDao userDao;
@Test
public void contextLoads() {
System.out.println(dictionaryDao.list());
System.out.println("===================");
System.out.println(userDao.list());
}
}