SpringBoot项目中的多数据源支持的方法

2023-09-22 18:31:06 299

1.概述

项目中经常会遇到一个应用需要访问多个数据源的情况，本文介绍在SpringBoot项目中利用SpringDataJpa技术如何支持多个数据库的数据源。

具体的代码参照该示例项目

2.建立实体类（Entity）

首先，我们创建两个简单的实体类，分别属于两个不同的数据源，用于演示多数据源数据的保存和查询。

Test实体类：

packagecom.example.demo.test.data;

importjavax.persistence.Entity;
importjavax.persistence.Id;
importjavax.persistence.Table;

@Entity
@Table(name="test")
publicclassTest{

@Id
privateIntegerid;

publicTest(){

}

publicIntegergetId(){
returnthis.id;
}

publicvoidsetId(Integerid){
this.id=id;
}
}

Other实体类：

packagecom.example.demo.other.data;

importjavax.persistence.Entity;
importjavax.persistence.Id;
importjavax.persistence.Table;

@Entity
@Table(name="other")
publicclassOther{

@Id
privateIntegerid;

publicIntegergetId(){
returnthis.id;
}

publicvoidsetId(Integerid){
this.id=id;
}
}

需要注意的是，这两个实体类分属于不同的package，这一点极为重要，spring会根据实体类所属的package来决定用那一个数据源进行操作。

3.建立Repository

分别建立两个实体类对应的Repository，用于进行数据操作。

TestRepository:

packagecom.example.demo.test.data;

importorg.springframework.data.jpa.repository.JpaRepository;

publicinterfaceTestRepositoryextendsJpaRepository{
}

OtherRepository:

packagecom.example.demo.other.data;

importorg.springframework.data.jpa.repository.JpaRepository;

publicinterfaceOtherRepositoryextendsJpaRepository{
}

得益于spring-data-jpa优秀的封装，我们只需创建一个接口，就拥有了对实体类的操作能力。

3.对多数据源进行配置

分别对Test和Other两个实体类配置对应的数据源。配置的内容主要包含三个要素：

dataSource，数据源的连接信息
entityManagerFactory，数据处理
transactionManager，事务管理

Test实体类的数据源配置TestDataConfig：

packagecom.example.demo.config;

importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.beans.factory.annotation.Qualifier;
importorg.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
importorg.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
importorg.springframework.boot.context.properties.ConfigurationProperties;
importorg.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importorg.springframework.context.annotation.Primary;
importorg.springframework.data.jpa.repository.config.EnableJpaRepositories;
importorg.springframework.orm.jpa.JpaTransactionManager;
importorg.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
importorg.springframework.transaction.PlatformTransactionManager;
importorg.springframework.transaction.annotation.EnableTransactionManagement;

importjavax.persistence.EntityManagerFactory;
importjavax.sql.DataSource;

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef="entityManagerFactory",
basePackages={"com.example.demo.test.data"}
)
publicclassTestDataConfig{

@Autowired
privateJpaPropertiesjpaProperties;

@Primary
@Bean(name="dataSource")
@ConfigurationProperties(prefix="spring.datasource")
publicDataSourcedataSource(){
returnDataSourceBuilder.create().build();
}

@Primary
@Bean(name="entityManagerFactory")
publicLocalContainerEntityManagerFactoryBeanentityManagerFactory(
EntityManagerFactoryBuilderbuilder,
@Qualifier("dataSource")DataSourcedataSource){
returnbuilder
.dataSource(dataSource)
.packages("com.example.demo.test.data")
.properties(jpaProperties.getHibernateProperties(dataSource))
.persistenceUnit("test")
.build();
}

@Primary
@Bean(name="transactionManager")
publicPlatformTransactionManagertransactionManager(
@Qualifier("entityManagerFactory")EntityManagerFactoryentityManagerFactory){
returnnewJpaTransactionManager(entityManagerFactory);
}

}

代码中的Primary注解表示这是默认数据源。

Other实体类的数据源配置OtherDataConfig：

packagecom.example.demo.config;

importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.beans.factory.annotation.Qualifier;
importorg.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
importorg.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
importorg.springframework.boot.context.properties.ConfigurationProperties;
importorg.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importorg.springframework.data.jpa.repository.config.EnableJpaRepositories;
importorg.springframework.orm.jpa.JpaTransactionManager;
importorg.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
importorg.springframework.transaction.PlatformTransactionManager;
importorg.springframework.transaction.annotation.EnableTransactionManagement;

importjavax.persistence.EntityManagerFactory;
importjavax.sql.DataSource;

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef="otherEntityManagerFactory",
transactionManagerRef="otherTransactionManager",
basePackages={"com.example.demo.other.data"}
)
publicclassOtherDataConfig{

@Autowired
privateJpaPropertiesjpaProperties;

@Bean(name="otherDataSource")
@ConfigurationProperties(prefix="other.datasource")
publicDataSourceotherDataSource(){
returnDataSourceBuilder.create().build();
}

@Bean(name="otherEntityManagerFactory")
publicLocalContainerEntityManagerFactoryBeanotherEntityManagerFactory(
EntityManagerFactoryBuilderbuilder,
@Qualifier("otherDataSource")DataSourceotherDataSource){
returnbuilder
.dataSource(otherDataSource)
.packages("com.example.demo.other.data")
.properties(jpaProperties.getHibernateProperties(otherDataSource))
.persistenceUnit("other")
.build();
}

@Bean(name="otherTransactionManager")
publicPlatformTransactionManagerotherTransactionManager(
@Qualifier("otherEntityManagerFactory")EntityManagerFactoryotherEntityManagerFactory){
returnnewJpaTransactionManager(otherEntityManagerFactory);
}

}

3.数据操作

我们创建一个Service类TestService来分别对两个数据源进行数据的操作。

packagecom.example.demo.service;

importcom.example.demo.other.data.Other;
importcom.example.demo.other.data.OtherRepository;
importcom.example.demo.test.data.Test;
importcom.example.demo.test.data.TestRepository;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.beans.factory.annotation.Value;
importorg.springframework.stereotype.Component;

@Component
publicclassTestService{

@Autowired
privateTestRepositorytestRepository;

@Autowired
privateOtherRepositoryotherRepository;

@Value("${name:World}")
privateStringname;

publicStringgetHelloMessage(){
Testtest=newTest();
test.setId(1);
test=testRepository.save(test);

Otherother=newOther();
other.setId(2);
other=otherRepository.save(other);

return"Hello"+this.name+":test'svalue="+test.getId()+",other'svalue="+other.getId();

}

}

对Test和Other分别进行数据插入和读取操作，程序运行后会打印出两个数据源各自的数据。数据库采用的mysql，连接信息在application.yml进行配置。

spring:
datasource:
url:jdbc:mysql://localhost:3306/test?characterEncoding=utf-8&useSSL=false
testWhileIdle:true
validationQuery:SELECT1fromdual
username:test
password:11111111
driverClassName:com.mysql.jdbc.Driver
jpa:
database:MYSQL
show-sql:true
hibernate:
show-sql:true
ddl-auto:create
naming-strategy:org.hibernate.cfg.ImprovedNamingStrategy
properties:
hibernate.dialect:org.hibernate.dialect.MySQL5Dialect
other:
datasource:
url:jdbc:mysql://localhost:3306/other?characterEncoding=utf-8&useSSL=false
testWhileIdle:true
validationQuery:SELECT1
username:other
password:11111111
driverClassName:com.mysql.jdbc.Driver
jpa:
database:MYSQL
show-sql:true
hibernate:
show-sql:true
ddl-auto:create
naming-strategy:org.hibernate.cfg.ImprovedNamingStrategy
properties:
hibernate.dialect:org.hibernate.dialect.MySQL5Dialect

Test实体对应的是主数据源，采用了spring-boot的默认数据源配置项，Other实体单独配置数据源连接。具体应该读取哪一段配置内容，是在配置类OtherDataConfig中这行代码指定的。

@ConfigurationProperties(prefix="other.datasource")

本示例需要建立的数据库用户和库可以通过以下命令处理：

CREATEUSER'test'@'localhost'IDENTIFIEDBY'11111111';
GRANTALLPRIVILEGESON*.*TO'test'@'localhost';
CREATEUSER'other'@'localhost'IDENTIFIEDBY'11111111';
GRANTALLPRIVILEGESON*.*TO'other'@'localhost';
createdatabasetest;
createdatabaseother;

4.总结

spring-data-jpa极大的简化了数据库操作，对于多数据源的支持，也只是需要增加一下配置文件和配置类而已。其中的关键内容有3点：

配置文件中数据源的配置
配置类的编写
实体类所在的package必须与配置类中指定的package一致，如OtherDataConfig中指定的basePackages={"com.example.demo.other.data"}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持毛票票。

SpringBoot项目中的多数据源支持的方法

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