为什么 spring-data-keyvalue 的 @KeySpace 实体需要 @Enitity

Question

在 https://www.baeldung.com/spring-data-key-value 使用 Spring 3.1 和 Java 17 时，我收到错误消息，除非我添加 @Enitity，否则不会创建 Repo。为什么？博客有错吗？我发现缺陷了吗？

没有@Entity的错误

2023-10-21T10:17:06.706-05:00 INFO 3536 --- [ main] .RepositoryConfigurationExtensionSupport ：Spring Data Map - 无法安全地识别存储库候选接口 com.example.demo.sql.Repo 的存储分配；如果您希望此存储库成为 Map 存储库，请考虑使用您的存储库扩展以下类型之一： org.springframework.data.keyvalue.repository.KeyValueRepository

pom.xml

<?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>3.1.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>demo</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.data</groupId>
            <artifactId>spring-data-keyvalue</artifactId>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </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>
            </plugin>
        </plugins>
    </build>
</project>

应用程序.属性

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=sa
spring.h2.console.enabled=true

spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.H2Dialect

package com.example.demo.sql;

import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import org.springframework.data.keyvalue.annotation.KeySpace;

@KeySpace
**@Entity**
public class KeyValue {
    @Id
    public String key;
    public String value;
}

package com.example.demo.sql;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface Repo extends CrudRepository<KeyValue, String> {
}

package com.example.demo;

import com.example.demo.sql.Repo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.data.map.repository.config.EnableMapRepositories;

@SpringBootApplication
@EnableMapRepositories
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    @Bean
    public String bean(Repo repo) {
        return repo.toString();
    }
}

Answer 1

根据https://github.com/spring-projects/spring-data-keyvalue/issues/541答案是，如果我不引入 spring-boot-starter-data-jpa 那么它无需引入

@Entity

注释。要构建加载 spring-data 的键值存储库，请使用

KeyValueRepository

而不是

CrudRepository

。