通过上下文检索存储库 Bean 返回"没有可用的合格 Bean

Question

我有一个非常简单的Springboot JPA项目，由一个主类、一个存储库和一个实体组成。首先，我遇到了一个问题，Springboot在启动时抛出一个错误，但这个问题已经解决了。现在我面临的问题是无法在我的主类中检索Repository Bean。

它抛出没有类型'com.d043114.minimalJPA '的合格bean。CityRepository available"

存储库如下所示

package com.d043114.minimalJPA;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface CityRepository extends CrudRepository<City, Long> {
}

实体是这样的:

package com.d043114.minimalJPA;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "cities")
public class City {
@Id
@GeneratedValue(strategy = GenerationType.AUTO )
private long ID;

public long getID() {
return ID;
}
public void setID(long iD) {
ID = iD;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
private String name;
}

main类也是basic类

package com.d043114.minimalJPA;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import com.d043114.minimalJPA.CityRepository;
@EnableJpaRepositories("com.d043114.minimalJPA.*")
@ComponentScan(basePackages = "com.d043114.minimalJPA.*")
@SpringBootApplication
@EntityScan("com.d043114.minimlaJPA")
public class MinimalJpaApplication {
public static void main(String[] args) {
ConfigurableApplicationContext appcontext = SpringApplication.run(MinimalJpaApplication.class, args);


CityRepository cityRepository =   appcontext.getBean(CityRepository.class );
}
}

Answer 1

问题在于这一行

@EnableJpaRepositories("com.d043114.minimalJPA.*")

用

代替

@EnableJpaRepositories("com.d043114.minimalJPA")

并删除这一行

@EntityScan("com.d043114.minimlaJPA")

It is working .

如果同时删除所有这些行，那么它也可以工作。

@EnableJpaRepositories("com.d043114.minimalJPA.*")
@ComponentScan(basePackages = "com.d043114.minimalJPA.*")

最后的代码是CityRepository.java

package com.d043114.minimalJPA;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface CityRepository extends CrudRepository<City, Long>
{
}

City.java

package com.d043114.minimalJPA;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "cities")
public class City
{
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long ID;
public long getID()
{
return ID;
}
public void setID(long iD)
{
ID = iD;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
private String name;
}

主类MinimalJpaApplication.java

@SpringBootApplication
public class MinimalJpaApplication
{
public static void main(String[] args)
{
ConfigurableApplicationContext appcontext = SpringApplication.run(MinimalJpaApplication.class, args);
CityRepository cityRepository =  appcontext.getBean(CityRepository.class );

if ( cityRepository != null )
{
System.out.println("We are goood ");
}
}
}

如果你展开@SpringBootApplication，你会看到它已经在处理所有这些事情了。

关于@ entitscan和@ComponentScan，请参阅下面的链接https://www.baeldung.com/spring-entityscan-vs-componentscan"我们应该意识到使用@ entitscan将禁用Spring Boot对实体的自动配置扫描。">

添加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>2.7.6</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.d043114</groupId>
<artifactId>minimalJPA </artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>minimalJPA </name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>11</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</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>