Spring Boot中配置多个数据源
配置数据源实际上就是配置多个数据库，在一个配置文件中配置多个数据库，这样做主要的好处有以下几点：
- 数据库隔离：通过配置多个数据源，可以将不同的业务数据存储在不同的数据库中，实现数据的隔离。这样可以提高系统的安全性和稳定性，避免不同业务之间的数据相互干扰。
- 性能优化：通过配置多个数据源，可以将读写操作分离到不同的数据库中，从而提高系统的并发性能。例如，将读操作集中在一个主数据库中，将写操作分散到多个从数据库中，可以有效地减轻数据库的读写压力，提高系统的响应速度。
- 扩展性：当系统需要扩展到多个地理位置或多个数据中心时，配置多个数据源可以更好地支持分布式部署。每个地理位置或数据中心可以配置一个独立的数据源，使得数据访问更加高效和可靠。
- 多租户支持：对于多租户的系统，配置多个数据源可以实现不同租户的数据隔离。每个租户可以拥有自己独立的数据库，从而保证数据的安全性和隐私性。
- 数据库版本升级：在进行数据库版本升级时，可以通过配置多个数据源，将新版本的数据库与旧版本的数据库并行使用。这样可以在升级过程中保证系统的正常运行，减少升级带来的风险。
我们目前常用的三种数据访问方法方式：
- JDBCTemplate
- Spring Data JPA
- MyBatis
接下来我们将围绕这种数据访问方法进行配置：
JDBCTemplate
实际上这种方式，主要还是在application.properties中设置我们需要链接的数据库配置，比如我A数据库用来存储用户信息，B数据库用来存储业务数据。
spring.datasource.primary.jdbc-url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
spring.datasource.primary.username=root
spring.datasource.primary.password=123456
spring.datasource.primary.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.secondary.jdbc-url=jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.cj.jdbc.Driver
ok，我们继续配置完毕后数据源后，我们就通过配置类来完成加载这些配置信息，初始话数据源，以及初始化每个数据源的时候要用的JDBCTemplate。你只需要在你的Spring Boot中应用下面的配置类就可以完成。
@Configuration
public class DataSourceConfiguration {
@Primary
@Bean
@ConfigurationProperties(prefix = "spring.datasource.primary")
public DataSource primaryDataSource() {
return DataSourceBuilder.create().build();
}
@Bean
@ConfigurationProperties(prefix = "spring.datasource.secondary")
public DataSource secondaryDataSource() {
return DataSourceBuilder.create().build();
}
@Bean
public JdbcTemplate primaryJdbcTemplate(@Qualifier("primaryDataSource") DataSource primaryDataSource) {
return new JdbcTemplate(primaryDataSource);
}
@Bean
public JdbcTemplate secondaryJdbcTemplate(@Qualifier("secondaryDataSource") DataSource secondaryDataSource) {
return new JdbcTemplate(secondaryDataSource);
}
}
<dependencies>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-webartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-jdbcartifactId>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
dependency>
<dependency>
<groupId>org.projectlombokgroupId>
<artifactId>lombokartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
dependencies>
单元测试类：
@RunWith(SpringRunner.class)
@SpringBootTest
public class ApplicationTests {
@Autowired
protected JdbcTemplate primaryJdbcTemplate;
@Autowired
protected JdbcTemplate secondaryJdbcTemplate;
@Before
public void setUp() {
primaryJdbcTemplate.update("DELETE FROM USER ");
secondaryJdbcTemplate.update("DELETE FROM USER ");
}
@Test
public void test() throws Exception {
// 往第一个数据源中插入 2 条数据
primaryJdbcTemplate.update("insert into user(name,age) values(?, ?)", "aaa", 20);
primaryJdbcTemplate.update("insert into user(name,age) values(?, ?)", "bbb", 30);
// 往第二个数据源中插入 1 条数据，若插入的是第一个数据源，则会主键冲突报错
secondaryJdbcTemplate.update("insert into user(name,age) values(?, ?)", "ccc", 20);
// 查一下第一个数据源中是否有 2 条数据，验证插入是否成功
Assert.assertEquals("2", primaryJdbcTemplate.queryForObject("select count(1) from user", String.class));
// 查一下第一个数据源中是否有 1 条数据，验证插入是否成功
Assert.assertEquals("1", secondaryJdbcTemplate.queryForObject("select count(1) from user", String.class));
}
}
有两个JdbcTemplate，为什么不用@Qualifier指定？这里顺带说个小知识点，当我们不指定的时候，会采用参数的名字来查找Bean，存在的话就注入。
这两个JdbcTemplate创建的时候，我们也没指定名字，它们是如何匹配上的？这里也是一个小知识点，当我们创建Bean的时候，默认会使用方法名称来作为Bean的名称，所以这里就对应上了。读者不妨回头看看两个名称是不是一致的。
Spring Data JPA
和上边那种方式基本上类似，所做的操作会有细微的区别。
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-webartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-data-jpaartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-actuatorartifactId>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
dependency>
<dependency>
<groupId>org.projectlombokgroupId>
<artifactId>lombokartifactId>
<scope>providedscope>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
配置application.properties文件
# pring boot 1.x的配置：spring.datasource.primary.url=jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
spring.datasource.primary.jdbc-url=jdbc:mysql://localhost:3306/test1
spring.datasource.primary.username=root
spring.datasource.primary.password=123456
spring.datasource.primary.driver-class-name=com.mysql.cj.jdbc.Driver
# spring boot 1.x的配置：spring.datasource.secondary.url=jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
spring.datasource.secondary.jdbc-url=jdbc:mysql://localhost:3306/test2
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.cj.jdbc.Driver
# 日志打印执行的SQL
spring.jpa.show-sql=true
# Hibernate的DDL策略
spring.jpa.hibernate.ddl-auto=create-drop
创建实体类：
@Entity
//@Data
//@NoArgsConstructor
public class User {
@Id
@GeneratedValue
private Long id;
private String name;
private Integer age;
public User(String name, Integer age) {
this.name = name;
this.age = age;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public User() {
}
}
public interface UserRepository extends JpaRepository<User, Long> {
}
@Entity
//@Data
//@NoArgsConstructor
public class Message {
@Id
@GeneratedValue
private Long id;
private String title;
private String message;
public Message(String title, String message) {
this.title = title;
this.message = message;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public Message() {
}
}
public interface MessageRepository extends JpaRepository<Message, Long> {
}
多数据源配置类：
@Configuration
public class DataSourceConfiguration {
@Primary
@Bean
@ConfigurationProperties(prefix = "spring.datasource.primary")
public DataSource primaryDataSource() {
return DataSourceBuilder.create().build();
}
@Bean
@ConfigurationProperties(prefix = "spring.datasource.secondary")
public DataSource secondaryDataSource() {
return DataSourceBuilder.create().build();
}
}
主数据源配置类：
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef="entityManagerFactoryPrimary",
transactionManagerRef="transactionManagerPrimary",
basePackages= { "com.miaow.demo.p" }) //设置Repository所在位置
public class PrimaryConfig {
@Autowired
@Qualifier("primaryDataSource")
private DataSource primaryDataSource;
@Autowired
private JpaProperties jpaProperties;
@Autowired
private HibernateProperties hibernateProperties;
private Map<String, Object> getVendorProperties() {
return hibernateProperties.determineHibernateProperties(jpaProperties.getProperties(), new HibernateSettings());
}
@Primary
@Bean(name = "entityManagerPrimary")
public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
return entityManagerFactoryPrimary(builder).getObject().createEntityManager();
}
@Primary
@Bean(name = "entityManagerFactoryPrimary")
public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary (EntityManagerFactoryBuilder builder) {
// HibernateJpaVendorAdapter jpaVendorAdapter = new HibernateJpaVendorAdapter();
// jpaVendorAdapter.setGenerateDdl(true);
return builder
.dataSource(primaryDataSource)
.packages("com.miaow.demo.p") //设置实体类所在位置
.persistenceUnit("primaryPersistenceUnit")
.properties(getVendorProperties())
.build();
}
@Primary
@Bean(name = "transactionManagerPrimary")
public PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder) {
return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());
}
}
设置从数据库配置类：
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef="entityManagerFactorySecondary",
transactionManagerRef="transactionManagerSecondary",
basePackages= { "com.miaow.demo.s" }) //设置Repository所在位置
public class SecondaryConfig {
@Autowired
@Qualifier("secondaryDataSource")
private DataSource secondaryDataSource;
@Autowired
private JpaProperties jpaProperties;
@Autowired
private HibernateProperties hibernateProperties;
private Map<String, Object> getVendorProperties() {
return hibernateProperties.determineHibernateProperties(jpaProperties.getProperties(), new HibernateSettings());
}
@Bean(name = "entityManagerSecondary")
public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
return entityManagerFactorySecondary(builder).getObject().createEntityManager();
}
@Bean(name = "entityManagerFactorySecondary")
public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary (EntityManagerFactoryBuilder builder) {
return builder
.dataSource(secondaryDataSource)
.packages("com.miaow.demo.s") //设置实体类所在位置
.persistenceUnit("secondaryPersistenceUnit")
.properties(getVendorProperties())
.build();
}
@Bean(name = "transactionManagerSecondary")
PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {
return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());
}
}
创建的单元测试：
@Slf4j
@RunWith(SpringRunner.class)
@SpringBootTest
public class ApplicationTests {
@Autowired
private UserRepository userRepository;
@Autowired
private MessageRepository messageRepository;
@Test
public void test() throws Exception {
userRepository.save(new User("aaa", 10));
userRepository.save(new User("bbb", 20));
userRepository.save(new User("ccc", 30));
userRepository.save(new User("ddd", 40));
userRepository.save(new User("eee", 50));
Assert.assertEquals(5, userRepository.findAll().size());
messageRepository.save(new Message("o1", "aaaaaaaaaa"));
messageRepository.save(new Message("o2", "bbbbbbbbbb"));
messageRepository.save(new Message("o3", "cccccccccc"));
Assert.assertEquals(3, messageRepository.findAll().size());
}
}
MyBatis
在Spring Boot的配置文件application.properties中设置我们需要的两个连接的数据库配置：
# pring boot 1.x的配置：spring.datasource.primary.url=jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
spring.datasource.primary.jdbc-url=jdbc:mysql://localhost:3306/test1
spring.datasource.primary.username=root
spring.datasource.primary.password=123456
spring.datasource.primary.driver-class-name=com.mysql.cj.jdbc.Driver
# spring boot 1.x的配置：spring.datasource.secondary.url=jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
spring.datasource.secondary.jdbc-url=jdbc:mysql://localhost:3306/test2
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.cj.jdbc.Driver
#mybatis.mapper-locations=classpath:mapper/*.xml
创建一个初始化多数据源和MyBatis配置
@Configuration
public class DataSourceConfiguration {
@Primary
@Bean
@ConfigurationProperties(prefix = "spring.datasource.primary")
public DataSource primaryDataSource() {
return DataSourceBuilder.create().build();
}
@Bean
@ConfigurationProperties(prefix = "spring.datasource.secondary")
public DataSource secondaryDataSource() {
return DataSourceBuilder.create().build();
}
}
可以看到内容跟JdbcTemplate、Spring Data JPA的时候是一模一样的。通过@ConfigurationProperties可以知道这两个数据源分别加载了spring.datasource.primary.*和spring.datasource.secondary.*的配置。@Primary注解指定了主数据源，就是当我们不特别指定哪个数据源的时候，就会使用这个Bean真正差异部分在下面的JPA配置上。
分别创建这两个数据源的MyBatis配置文件：
Private 数据源的JPA的配置文件：
@Configuration
@MapperScan(
basePackages = "com.miaow.demo.p",
sqlSessionFactoryRef = "sqlSessionFactoryPrimary",
sqlSessionTemplateRef = "sqlSessionTemplatePrimary")
public class PrimaryConfig {
private DataSource primaryDataSource;
public PrimaryConfig(@Qualifier("primaryDataSource") DataSource primaryDataSource) {
this.primaryDataSource = primaryDataSource;
}
@Bean
public SqlSessionFactory sqlSessionFactoryPrimary() throws Exception {
SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
bean.setDataSource(primaryDataSource);
return bean.getObject();
}
@Bean
public SqlSessionTemplate sqlSessionTemplatePrimary() throws Exception {
return new SqlSessionTemplate(sqlSessionFactoryPrimary());
}
}
Secondary的数据源JPA配置：
@Configuration
@MapperScan(
basePackages = "com.miaow.demo.s",
sqlSessionFactoryRef = "sqlSessionFactorySecondary",
sqlSessionTemplateRef = "sqlSessionTemplateSecondary")
public class SecondaryConfig {
private DataSource secondaryDataSource;
public SecondaryConfig(@Qualifier("secondaryDataSource") DataSource secondaryDataSource) {
this.secondaryDataSource = secondaryDataSource;
}
@Bean
public SqlSessionFactory sqlSessionFactorySecondary() throws Exception {
SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
bean.setDataSource(secondaryDataSource);
return bean.getObject();
}
@Bean
public SqlSessionTemplate sqlSessionTemplateSecondary() throws Exception {
return new SqlSessionTemplate(sqlSessionFactorySecondary());
}
}
注意在此说明一下，配置类上使用@MapperScan注解来指定当前数据源下定义的Entity和Mapper的包路径；
另外需要指定sqlSessionFactory和sqlSessionTemplate，这两个具体实现在该配置类中类中初始化。
配置类的构造函数中，通过@Qualifier注解来指定具体要用哪个数据源，其名字对应在DataSourceConfiguration配置类中的数据源定义的函数名。
配置类中定义SqlSessionFactory和SqlSessionTemplate的实现，注意具体使用的数据源正确。
创建一个UserPrimary实体类:
public class UserPrimary {
private Long id;
private String name;
private Integer age;
public UserPrimary(String name, Integer age) {
this.name = name;
this.age = age;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public UserPrimary() {
}
}
创建一个UserMapperPrimary用来作为填写SQL语句的接口：
public interface UserMapperPrimary {
@Select("SELECT * FROM USER WHERE NAME = #{name}")
UserPrimary findByName(@Param("name") String name);
@Insert("INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})")
int insert(@Param("name") String name, @Param("age") Integer age);
@Delete("DELETE FROM USER")
int deleteAll();
}
创建一个UserSecondary实体类：
public class UserSecondary {
private Long id;
private String name;
private Integer age;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public UserSecondary() {
}
public UserSecondary(String name, Integer age) {
this.name = name;
this.age = age;
}
}
public interface UserMapperSecondary {
@Select("SELECT * FROM USER WHERE NAME = #{name}")
UserSecondary findByName(@Param("name") String name);
@Insert("INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})")
int insert(@Param("name") String name, @Param("age") Integer age);
@Delete("DELETE FROM USER")
int deleteAll();
}
之后，也是最关键的一步，我们需要在MyBatis的配置文件中使用Mapper.xml
在Resources目录下创建一个mapper文件夹，之后再mapper文件夹下边分别创建primary和secondary文件夹：
UserMapper.xml
DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.miaow.demo.p.mapper.UserMapperPrimary">
<select id="findByName" resultType="com.miaow.demo.p.entity.UserPrimary">
SELECT * FROM USER WHERE NAME = #{name}
select>
<insert id="insert">
INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})
insert>
mapper>
与上边这个几乎一样，只是两者指向的接口位置不一样：
DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.miaow.demo.s.mapper.UserMapperSecondary">
<select id="findByName" resultType="com.miaow.demo.s.entity.UserSecondary">
SELECT * FROM USER WHERE NAME = #{name}
select>
<insert id="insert">
INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})
insert>
mapper>
最后我们可以通过一个测试类进行测试：
@Slf4j
@RunWith(SpringRunner.class)
@SpringBootTest
@Transactional
public class ApplicationTests {
//第一数据库配置类
@Autowired
private UserMapperPrimary userMapperPrimary;
//第二数据库配置文件
@Autowired
private UserMapperSecondary userMapperSecondary;
@Before
public void setUp() {
// 清空测试表，保证每次结果一样
userMapperPrimary.deleteAll();
userMapperSecondary.deleteAll();
}
@Test
public void test() throws Exception {
// 往Primary数据源插入一条数据
userMapperPrimary.insert("AAA", 20);
// 从Primary数据源查询刚才插入的数据，配置正确就可以查询到
UserPrimary userPrimary = userMapperPrimary.findByName("AAA");
Assert.assertEquals(20, userPrimary.getAge().intValue());
// 从Secondary数据源查询刚才插入的数据，配置正确应该是查询不到的
UserSecondary userSecondary = userMapperSecondary.findByName("AAA");
Assert.assertNull(userSecondary);
// 往Secondary数据源插入一条数据
userMapperSecondary.insert("BBB", 20);
// 从Primary数据源查询刚才插入的数据，配置正确应该是查询不到的
userPrimary = userMapperPrimary.findByName("BBB");
Assert.assertNull(userPrimary);
// 从Secondary数据源查询刚才插入的数据，配置正确就可以查询到
userSecondary = userMapperSecondary.findByName("BBB");
Assert.assertEquals(20, userSecondary.getAge().intValue());
}
}