在spring boot中使用mongodb从两个集合中获取数据

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>

@Configuration
public class MongoConfig {

    @Value("${spring.data.mongodb.host}")
    private String host;

    @Value("${spring.data.mongodb.port}")
    private int port;

    @Value("${spring.data.mongodb.database}")
    private String database;

    @Bean
    public MongoClient mongoClient() {
        return new MongoClient(host, port);
    }

    @Bean
    public MongoTemplate mongoTemplate() {
        return new MongoTemplate(mongoClient(), database);
    }
}

@Document(collection = "collection_a")
public class CollectionA {
    // 实体类属性
}

@Document(collection = "collection_b")
public class CollectionB {
    // 实体类属性
}

@Autowired
private MongoTemplate mongoTemplate;

public List<CollectionA> findDataFromCollectionA() {
    Query query = new Query();
    // 设置查询条件
    // query.addCriteria(...);

    return mongoTemplate.find(query, CollectionA.class);
}

public List<CollectionB> findDataFromCollectionB() {
    Query query = new Query();
    // 设置查询条件
    // query.addCriteria(...);

    return mongoTemplate.find(query, CollectionB.class);
}

public interface CollectionARepository extends MongoRepository<CollectionA, String> {
    // 可以在此定义一些自定义的查询方法
}

public interface CollectionBRepository extends MongoRepository<CollectionB, String> {
    // 可以在此定义一些自定义的查询方法
}

@Autowired
private CollectionARepository collectionARepository;

@Autowired
private CollectionBRepository collectionBRepository;

public List<CollectionA> findDataFromCollectionA() {
    // 使用Repository提供的方法进行查询
    return collectionARepository.findAll();
}

public List<CollectionB> findDataFromCollectionB() {
    // 使用Repository提供的方法进行查询
    return collectionBRepository.findAll();
}