SpringBoot项目中的多数据源支持的方法

2019-11-26 11:06:49

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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：

package com.example.demo.test.data;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "test")public class Test {  @Id  private Integer id;  public Test(){  }  public Integer getId() {    return this.id;  }  public void setId(Integer id){    this.id = id;  }}

Other实体类：

package com.example.demo.other.data;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "other")public class Other {  @Id  private Integer id;  public Integer getId() {    return this.id;  }  public void setId(Integer id){    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:

package com.example.demo.test.data;import org.springframework.data.jpa.repository.JpaRepository;public interface TestRepository extends JpaRepository<Test, Integer> {}

OtherRepository:

package com.example.demo.other.data;import org.springframework.data.jpa.repository.JpaRepository;public interface OtherRepository extends JpaRepository<Other, Integer> {}

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：

package com.example.demo.config;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;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.transaction.PlatformTransactionManager;import org.springframework.transaction.annotation.EnableTransactionManagement;import javax.persistence.EntityManagerFactory;import javax.sql.DataSource;@Configuration@EnableTransactionManagement@EnableJpaRepositories(    entityManagerFactoryRef = "entityManagerFactory",    basePackages = {"com.example.demo.test.data"})public class TestDataConfig {  @Autowired  private JpaProperties jpaProperties;  @Primary  @Bean(name = "dataSource")  @ConfigurationProperties(prefix = "spring.datasource")  public DataSource dataSource() {    return DataSourceBuilder.create().build();  }  @Primary  @Bean(name = "entityManagerFactory")  public LocalContainerEntityManagerFactoryBean entityManagerFactory(      EntityManagerFactoryBuilder builder,      @Qualifier("dataSource") DataSource dataSource) {    return builder        .dataSource(dataSource)        .packages("com.example.demo.test.data")        .properties(jpaProperties.getHibernateProperties(dataSource))        .persistenceUnit("test")        .build();  }  @Primary  @Bean(name = "transactionManager")  public PlatformTransactionManager transactionManager(      @Qualifier("entityManagerFactory") EntityManagerFactory entityManagerFactory) {    return new JpaTransactionManager(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：

package com.example.demo.config;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;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.transaction.PlatformTransactionManager;import org.springframework.transaction.annotation.EnableTransactionManagement;import javax.persistence.EntityManagerFactory;import javax.sql.DataSource;@Configuration@EnableTransactionManagement@EnableJpaRepositories(    entityManagerFactoryRef = "otherEntityManagerFactory",    transactionManagerRef = "otherTransactionManager",    basePackages = {"com.example.demo.other.data"})public class OtherDataConfig {  @Autowired  private JpaProperties jpaProperties;  @Bean(name = "otherDataSource")  @ConfigurationProperties(prefix = "other.datasource")  public DataSource otherDataSource() {    return DataSourceBuilder.create().build();  }  @Bean(name = "otherEntityManagerFactory")  public LocalContainerEntityManagerFactoryBean otherEntityManagerFactory(      EntityManagerFactoryBuilder builder,      @Qualifier("otherDataSource") DataSource otherDataSource) {    return builder        .dataSource(otherDataSource)        .packages("com.example.demo.other.data")        .properties(jpaProperties.getHibernateProperties(otherDataSource))        .persistenceUnit("other")        .build();  }  @Bean(name = "otherTransactionManager")  public PlatformTransactionManager otherTransactionManager(      @Qualifier("otherEntityManagerFactory") EntityManagerFactory otherEntityManagerFactory) {    return new JpaTransactionManager(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。

package com.example.demo.service;import com.example.demo.other.data.Other;import com.example.demo.other.data.OtherRepository;import com.example.demo.test.data.Test;import com.example.demo.test.data.TestRepository;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Component;@Componentpublic class TestService {  @Autowired  private TestRepository testRepository;  @Autowired  private OtherRepository otherRepository;  @Value("${name:World}")  private String name;  public String getHelloMessage() {    Test test = new Test();    test.setId(1);    test = testRepository.save(test);    Other other = new Other();    other.setId(2);    other = otherRepository.save(other);    return "Hello " + this.name + " : test's value = " + test.getId() + " , other's value = " + 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: SELECT 1 from dual  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.MySQL5Dialectother: datasource:  url: jdbc:mysql://localhost:3306/other?characterEncoding=utf-8&useSSL=false  testWhileIdle: true  validationQuery: SELECT 1  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：

CREATE USER 'test'@'localhost' IDENTIFIED BY '11111111';GRANT ALL PRIVILEGES ON *.* TO 'test'@'localhost';CREATE USER 'other'@'localhost' IDENTIFIED BY '11111111';GRANT ALL PRIVILEGES ON *.* TO 'other'@'localhost';create database test;create database other;

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：