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网上大牛们的建议：一个系统最好一个数据源，多个数据源考虑使用微服务。
一、开发环境：
1.maven(version3.8.1)依赖：
<dependency>
? ? <groupId>org.springframework.boot</groupId>
? ? <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
? ? <groupId>org.springframework.boot</groupId>
? ? <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
? ? <groupId>mysql</groupId>
? ? <artifactId>mysql-connector-java</artifactId>
? ? <scope>runtime</scope>
</dependency>
<dependency>
? ? <groupId>org.projectlombok</groupId>
? ? <artifactId>lombok</artifactId>
? ? <optional>true</optional>
</dependency>
2.java版本：17
3.springboot版本：2.7.4
4.mysql5.8
二、开发步骤
包路径约定：com.example.multiple-database.one 下放数据库1对应的类，com.example.multiple-database.two下放数据库2对应的类
1.在配置文件application.properties里添加参数：
spring.jpa.open-in-view=false
spring.datasource.jdbc-url=jdbc:mysql://127.0.0.1:3306/my_database_one?useUnicode=true&characterEncoding=UTF-8&useSSL=true&serverTimezone=Asia/Shanghai
spring.datasource.username=your database one username
spring.datasource.password=your database one password
spring.second-datasource.jdbc-url=jdbc:mysql://127.0.0.1:3306/my_database_two?useUnicode=true&characterEncoding=UTF-8&useSSL=true&serverTimezone=Asia/Shanghai
spring.second-datasource.username=your database two username
spring.second-datasource.password=your database two password
2.添加数据库1的配置类
package?com.example.multiple-database.config;
import?org.springframework.boot.context.properties.ConfigurationProperties;
import?org.springframework.boot.jdbc.DataSourceBuilder;
import?org.springframework.context.annotation.Bean;
import?org.springframework.context.annotation.Configuration;
import?org.springframework.context.annotation.Primary;
import?org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import?org.springframework.orm.jpa.JpaTransactionManager;
import?org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import?org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import?org.springframework.transaction.PlatformTransactionManager;
import?javax.sql.DataSource;
import?java.util.HashMap;
import?java.util.Map;
@Configuration
@EnableJpaRepositories(
? ? ? ? basePackages =?"com.example.multiple-database.one",
? ? ? ??entityManagerFactoryRef =?"dbOneEntityManager", ? ? ? ? //对应下面定义的entityManager函数名字
? ? ? ??transactionManagerRef =?"dbOneTransactionManager")?//对应下面事务管理的函数名字
public class?DatabaseOneConfig {
? ??@Bean
? ? @Primary
? ? @ConfigurationProperties(prefix =?"spring.datasource")
? ??public?DataSource?dbOneDataSource(){
? ? ? ??return?DataSourceBuilder.create().build();
? ??}
? ??@Bean
? ??public?LocalContainerEntityManagerFactoryBean?dbOneEntityManager(){
? ? ? ? LocalContainerEntityManagerFactoryBean em =?new?LocalContainerEntityManagerFactoryBean();
? ? ? ??em.setDataSource(mainDataSource());
? ? ? ??em.setPackagesToScan("com.example.multiple-database.one"); //这个包路径下放跟dbOne相关的类
? ? ? ??HibernateJpaVendorAdapter adapter =?new?HibernateJpaVendorAdapter();
? ? ? ??em.setJpaVendorAdapter(adapter);
? ? ? ??Map<String,?Object> properties =?new?HashMap<>();
? ? ? ??properties.put("hibernate.dialect",?"org.hibernate.dialect.MySQLInnoDBDialect");
? ? ? ??properties.put("hibernate.physical_naming_strategy",?"org.hibernate.boot.model.naming.CamelCaseToUnderscoresNamingStrategy");
? ? ? ??properties.put("hibernate.implicit_naming_strategy",?"org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy");
? ? ? ??em.setJpaPropertyMap(properties);
? ? ? ? return?em;
? ??}
? ??@Bean
? ? @Primary
? ??public?PlatformTransactionManager?dbOneTransactionManager(){
? ? ? ? JpaTransactionManager manager =?new?JpaTransactionManager();
? ? ? ??manager.setEntityManagerFactory(dbOneEntityManager().getObject());
? ? ? ? return?manager;
? ??}
}
3.添加数据库2的配置类
package?com.example.multiple-database.config;
import?org.springframework.boot.context.properties.ConfigurationProperties;
import?org.springframework.boot.jdbc.DataSourceBuilder;
import?org.springframework.context.annotation.Bean;
import?org.springframework.context.annotation.Configuration;
import?org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import?org.springframework.orm.jpa.JpaTransactionManager;
import?org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import?org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import?org.springframework.transaction.PlatformTransactionManager;
import?javax.sql.DataSource;
import?java.util.HashMap;
import?java.util.Map;
@Configuration
@EnableJpaRepositories(
? ? ? ? basePackages =?"com.example.multiple-database.two",
? ? ? ??entityManagerFactoryRef =?"dbTwoEntityManager", //对应下面实体类管理函数名
? ? ? ??transactionManagerRef =?"dbTwoTransactionManager")//对应下面事务管理函数名
public class?DatabaseTwoConfig?{
? ??@Bean
? ? @ConfigurationProperties(prefix =?"spring.second-datasource")
? ??public?DataSource?oldDataSource(){
? ? ? ??return?DataSourceBuilder.create().build();
? ??}
? ??@Bean
? ??public?LocalContainerEntityManagerFactoryBean?dbTwoEntityManager(){
? ? ? ? LocalContainerEntityManagerFactoryBean em =?new?LocalContainerEntityManagerFactoryBean();
? ? ? ??em.setDataSource(oldDataSource());
? ? ? ??em.setPackagesToScan("com.example.multiple-database.two"); //数据库2的实体类扫描路径
? ? ? ??HibernateJpaVendorAdapter adapter =?new?HibernateJpaVendorAdapter();
? ? ? ??em.setJpaVendorAdapter(adapter);
? ? ? ??Map<String,?Object> properties =?new?HashMap<>();
? ? ? ??properties.put("hibernate.dialect",?"org.hibernate.dialect.MySQLInnoDBDialect");
? ? ? ??properties.put("hibernate.physical_naming_strategy",?"org.hibernate.boot.model.naming.CamelCaseToUnderscoresNamingStrategy");
? ? ? ??properties.put("hibernate.implicit_naming_strategy",?"org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy");
? ? ? ??em.setJpaPropertyMap(properties);
? ? ? ? return?em;
? ??}
? ??@Bean
? ??public?PlatformTransactionManager?dbTwoTransactionManager(){
? ? ? ? JpaTransactionManager manager =?new?JpaTransactionManager();
? ? ? ??manager.setEntityManagerFactory(dbTwoEntityManager().getObject());
? ? ? ? return?manager;
? ??}
}
三、使用
1.查询：跟单数库使用好像没啥区别
2.(增删改)事务：
? ?@Transactional
? ?public void?save(Project project){
? ? ? ??projectRepository.save(project);
? ?}
?
更多参考：
Spring JPA – Multiple Databases | Baeldung
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