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Spring Boot应用中集成与使用多数据源

1. 前言

通过定义和使用多个数据源，能在Spring Boot应用中实现更复杂的数据管理场景，比如读写分离、数据冗余等。

2. 准备工作

• 环境准备：确保已经准备好Spring Boot的开发环境。
• 数据库准备：在本地或云服务上创建两个数据库，如下文所示。

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3. 创建Spring Boot项目

1. 使用Spring Initializr创建项目：https://start.spring.io/。
2. 在pom.xml中添加必要的依赖，包括JPA、Spring Boot Parent、数据库驱动等。

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4. 配置多数据源

在application.yml或application.properties中配置：

# application.yml
spring:datasource:primary:url: jdbc:mysql://localhost:3306/db1username: userpassword: passworddriver-class-name: com.mysql.jdbc.Driverhikari:connection-timeout: 30000maximum-pool-size: 20secondary:url: jdbc:mysql://localhost:3306/db2username: userpassword: passworddriver-class-name: com.mysql.jdbc.Driverhikari:connection-timeout: 30000maximum-pool-size: 20

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5. 创建实体类及Repository

Entity Class - User (For Primary Database):

package com.example.multidatasource.entity;import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;@Entity
@Table(name = "users")
public class User {@Idprivate Long id;private String name;private String email;// getter, setter, constructors
}

Entity Class - Product (For Secondary Database):

package com.example.multidatasource.entity;import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;@Entity
@Table(name = "products")
public class Product {@Idprivate Long id;private String name;private int price;// getter, setter, constructors
}

Repository (Primary):

package com.example.multidatasource.repository;import com.example.multidatasource.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;@Repository
public interface UserRepository extends JpaRepository<User, Long> {
}

Repository (Secondary):

package com.example.multidatasource.repository;import com.example.multidatasource.entity.Product;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;@Repository
public interface ProductRepository extends JpaRepository<Product, Long> {
}

6. 服务层配置与使用多数据源

package com.example.multidatasource.service;import com.example.multidatasource.entity.Product;
import com.example.multidatasource.repository.ProductRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class ProductService {private final ProductRepository productRepository;@Autowiredpublic ProductService(ProductRepository productRepository) {this.productRepository = productRepository;}public Product createProduct(String name, int price) {Product product = new Product();product.setName(name);product.setPrice(price);return productRepository.save(product);}
}

服务层同样应当遵循具体数据源的配置，确保通过合适的数据源进行持久化操作。

7. 事务与多数据源管理

针对跨数据源的事务操作，需要在@Service中配置@Transactional注解：

@Service
public class MultiDataSourceTransactionService {private final UserRepository userRepository;private final ProductRepository productRepository;@Autowiredpublic MultiDataSourceTransactionService(UserRepository userRepository, ProductRepository productRepository) {this.userRepository = userRepository;this.productRepository = productRepository;}// So that it's only using the primary dataSource@Transactional(propagation = Propagation.REQUIRED)public void performCreateUserAndProduct() {userRepository.save(new User("John Doe", "john@example.com"));productRepository.save(new Product("Widget", 1000));}
}

通过这种方式，可以确保同一个请求中的所有操作，要么全部成功，要么全部回滚。

8. 配置及测试

确保所有的Bean和配置类被正确注解，测试应用是否能够启动，数据源是否能够正确读写数据。