讲解下SpringBoot中MySql和MongoDB的配合使用

在Spring Boot中，MySQL和MongoDB可以配合使用，以充分发挥关系型数据库和非关系型数据库的优势。MySQL适合处理结构化数据，而MongoDB适合处理非结构化或半结构化数据。以下是如何在Spring Boot中同时使用MySQL和MongoDB的详细讲解。

1. 添加依赖

首先，在pom.xml中添加MySQL和MongoDB的依赖：

<dependencies>
    <!-- Spring Boot Starter Data JPA for MySQL -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>

    <!-- Spring Boot Starter Data MongoDB -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-mongodb</artifactId>
    </dependency>

    <!-- Other dependencies -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

2. 配置数据源

在application.properties或application.yml中配置MySQL和MongoDB的连接信息。

`application.properties` 示例：

# MySQL 配置
spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=password
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.hibernate.ddl-auto=update

# MongoDB 配置
spring.data.mongodb.uri=mongodb://localhost:27017/mydb

`application.yml` 示例：

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/mydb
    username: root
    password: password
    driver-class-name: com.mysql.cj.jdbc.Driver
  jpa:
    hibernate:
      ddl-auto: update
  data:
    mongodb:
      uri: mongodb://localhost:27017/mydb

3. 创建实体类和Repository

MySQL 实体类和Repository

创建一个MySQL实体类并使用JPA注解进行映射：

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String email;

    // Getters and Setters
}

创建对应的JPA Repository：

import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
}

MongoDB 实体类和Repository

创建一个MongoDB实体类并使用MongoDB注解进行映射：

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Document
public class Product {
    @Id
    private String id;
    private String name;
    private double price;

    // Getters and Setters
}

创建对应的MongoDB Repository：

import org.springframework.data.mongodb.repository.MongoRepository;

public interface ProductRepository extends MongoRepository<Product, String> {
}

4. 使用不同的Repository进行操作

在Service或Controller中，你可以分别使用UserRepository和ProductRepository来操作MySQL和MongoDB。

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MyService {

    @Autowired
    private UserRepository userRepository;

    @Autowired
    private ProductRepository productRepository;

    public void addUser(User user) {
        userRepository.save(user);
    }

    public void addProduct(Product product) {
        productRepository.save(product);
    }

    public User getUserById(Long id) {
        return userRepository.findById(id).orElse(null);
    }

    public Product getProductById(String id) {
        return productRepository.findById(id).orElse(null);
    }
}