在 Spring Boot 应用程序中配置多个数据源(Configure Multiple Datasource in Spring Boot Application)

有时我们会构建一些需要多个数据库的应用程序。我们的数据会被安排存储在多个数据库中，例如，一个数据库用于满足另一个需求，另一个数据库用于满足另一个需求。因此，在本文中，我们将了解如何在 Spring Boot 应用程序中配置多个数据库。

注意：我们对两个数据库都使用 MySQL 8 工作台。

在 Spring Boot 应用程序中配置多个数据源的步骤

以下是在 Spring Boot 应用程序中配置多个数据源的步骤。

步骤1

首先，我们需要配置属性文件。

application.properties:

# DataSource configuration
#DB1
spring.datasource.url=jdbc:mysql://localhost:8084/db1
spring.datasource.username=root
spring.datasource.password=tisha
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

#DB2
second.datasource.url=jdbc:mysql://localhost:8084/db2
second.datasource.username=root
second.datasource.password=tisha
second.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# JPA (Java Persistence API) configuration
spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect
# create,update,delete
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true

步骤2

现在，我们将在pom.xml文件中配置依赖项。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>org.techous</groupId>
    <artifactId>Trigger-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Trigger-demo</name>
    <description>master slave project for Spring Boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <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>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

项目结构

下面我们可以看到设计多个数据源后的项目结构。

首先，我们根据上图进行数据库1的配置。

项目实现 

Db1Config.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.env.Environment;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "firstEntityManagerFactoryBean",
        basePackages = {"org.techous.triggerdemo.db1.repository"},
        transactionManagerRef = "firstTransactionManager"
)
public class Db1Config {

    @Autowired
    private Environment environment;

    @Bean(name = "firstDataSource")
    @Primary
    public DataSource dataSource(){
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setUrl(environment.getProperty("spring.datasource.url"));
        dataSource.setDriverClassName(environment.getProperty("spring.datasource.driver-class-name"));
        dataSource.setUsername(environment.getProperty("spring.datasource.username"));
        dataSource.setPassword(environment.getProperty("spring.datasource.password"));

        return dataSource;
    }

    @Primary
    @Bean(name = "firstEntityManagerFactoryBean")
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean(){
        LocalContainerEntityManagerFactoryBean bean = new LocalContainerEntityManagerFactoryBean();
        bean.setDataSource(dataSource());
        bean.setPackagesToScan("org.techous.triggerdemo.db1.model");

        JpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        bean.setJpaVendorAdapter(adapter);

        Map<String,String> props = new HashMap<>();
        props.put("hibernate.dialect","org.hibernate.dialect.MySQLDialect");
        props.put("hibernate.show_sql","true");
        props.put("hibernate.hbm2ddl.auto","update");
        bean.setJpaPropertyMap(props);

        return bean;
    }

    @Bean(name = "firstTransactionManager")
    @Primary
    public PlatformTransactionManager transactionManager(){
        JpaTransactionManager manager = new JpaTransactionManager();
        manager.setEntityManagerFactory(entityManagerFactoryBean().getObject());
        return manager;
    }
}

在上面的代码中，我们添加了用于调用 db1 的配置。我们在此类中使用了 @configuration 注释，并将其转换为 bean。这里我们使用 Environment 类来配置内部环境，然后使用 Datasourse 进行不同的数据库配置。然后使用 LocalContinerEntityManager 来设置哪个包会首先扫描并运行我们指定的数据库路径，并将所有数据存储在那里。此配置仅用于创建多个数据源。其余部分就像简单的 crud 操作一样，我们已经完成了。

ProductController.java

package org.techous.triggerdemo.db1.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.techous.triggerdemo.db1.model.Product;
import org.techous.triggerdemo.db1.service.ProductService;

// Controller class for handling product-related requests
@RestController
@RequestMapping("/product")
public class ProductController {

    @Autowired
    private ProductService productService;

    // Endpoint for saving a product
    @PostMapping("saveProduct")
    public ResponseEntity<Product> saveProduct(@RequestBody Product product){
        Product myproduct = productService.saveProduct(product);
        return new ResponseEntity<>(myproduct, HttpStatus.OK);
    }

}

上述类是调用 API 的服务类端点。

ProductService.java 

package org.techous.triggerdemo.db1.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.techous.triggerdemo.db1.model.Product;
import org.techous.triggerdemo.db1.repository.ProductRepo;

// Service class for product-related operations
@Service
public class ProductService {

    @Autowired
    private ProductRepo productRepo;

    // Method to save a product
    public Product saveProduct(Product product) {
        return productRepo.save(product);
    }
}

上面的类是productService类，用于在这里实现所有的业务逻辑。 

Product.java

package org.techous.triggerdemo.db1.model;

import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.Table;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

// Entity class for Product
@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "product")
public class Product {

    @Id
    private int productId;
    private String name;
    private int price;
}

上面的类就是我们的实体类。

ProductRepo.java

package org.techous.triggerdemo.db1.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import org.techous.triggerdemo.db1.model.Product;

// Repository interface for Product
@Repository
public interface ProductRepo extends JpaRepository<Product,Integer> {

}

上述类是我们保存任何内容的存储库。

这是数据库 1（db1）的配置。

现在，我们下面进行另一个数据库（db2）的配置。

Db2Config2.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "secondEntityManagerFactoryBean",
        basePackages = {"org.techous.triggerdemo.db2.repository"},
        transactionManagerRef = "secondTransactionManager"
)
public class Db2Config {

    @Autowired
    private Environment environment;

    @Bean(name = "secondDataSource")
    public DataSource dataSource(){
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setUrl(environment.getProperty("second.datasource.url"));
        dataSource.setDriverClassName(environment.getProperty("second.datasource.driver-class-name"));
        dataSource.setUsername(environment.getProperty("second.datasource.username"));
        dataSource.setPassword(environment.getProperty("second.datasource.password"));

        return dataSource;
    }

    @Bean(name = "secondEntityManagerFactoryBean")
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean(){
        LocalContainerEntityManagerFactoryBean bean = new LocalContainerEntityManagerFactoryBean();
        bean.setDataSource(dataSource());
        bean.setPackagesToScan("org.techous.triggerdemo.db2.model");

        JpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        bean.setJpaVendorAdapter(adapter);

        Map<String,String> props = new HashMap<>();
        props.put("hibernate.dialect","org.hibernate.dialect.MySQLDialect");
        props.put("hibernate.show_sql","true");
        props.put("hibernate.hbm2ddl.auto","update");
        bean.setJpaPropertyMap(props);

        return bean;
    }

    @Bean(name = "secondTransactionManager")
    public PlatformTransactionManager transactionManager(){
        JpaTransactionManager manager = new JpaTransactionManager();
        manager.setEntityManagerFactory(entityManagerFactoryBean().getObject());
        return manager;
    }
}

如上所述，这里也进行相同的配置，并根据我们的数据库设计定义属性路径。（仅更改包 URL）

UserController.java 

package org.techous.triggerdemo.db2.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.techous.triggerdemo.db2.model.User;
import org.techous.triggerdemo.db2.service.UserService;

@RestController
@RequestMapping("/api")
public class UserController {

    @Autowired
    private UserService userService;

    // Endpoint to save a user
    @PostMapping("/saveUser")
    public ResponseEntity<User> save(@RequestBody User user){
        User myuser = userService.saveUser(user);
        return new ResponseEntity<>(myuser, HttpStatus.OK);
    }

}

UserService.java 

package org.techous.triggerdemo.db2.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.techous.triggerdemo.db2.model.User;
import org.techous.triggerdemo.db2.repository.UserRepository;

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    // Service method to save a user
    public User saveUser(User user) {
        return userRepository.save(user);
    }
}

User.java 

package org.techous.triggerdemo.db2.model;

import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int userId; // Unique identifier for the user

    private String name; // Name of the user

    private int age; // Age of the user
}

UserRepository.java 

package org.techous.triggerdemo.db2.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import org.techous.triggerdemo.db2.model.User;

@Repository
public interface UserRepository extends JpaRepository<User,Integer> {
}

我们已经完成了所有数据库配置。

现在，当我们插入用户时，它将保存在 db2 数据库中，而当我们保存产品时，它将保存在 db1 中。

输出

首先，我们将添加用户。

在下面的屏幕中，我们可以看到添加到数据库的用户。

现在，我们将添加产品。

现在，我们可以看到产品已添加到数据库中。

这样，我们可以在单个 Spring Boot 应用程序中配置多个数据源。

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