Question

一些细节 我在运行下面给出的代码时遇到了一些问题。我收到以下异常。当我尝试[CrudRepository for Spring Data]的示例代码时[1]。

我有一个界面：

package com.joydeep.springboot; 

import org.springframework.data.repository.CrudRepository; 
import com.joydeep.springboot.vo.Message; 

public interface Test1 extends CrudRepository<Message, String> { }

VO课程：

package com.joydeep.springboot.vo;

import java.util.Date;    
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Message {
    @Id
    private String id;
    private String text;
    private String author;
    private Date created;

    public Message() {
        super();
    }
    public Message(String id, String text, String author, Date created) {
        super();
        this.id = id;
        this.text = text;
        this.author = author;
        this.created = created;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getText() {
        return text;
    }
    public void setText(String text) {
        this.text = text;
    }
    public String getAuthor() {
        return author;
    }
    public void setAuthor(String author) {
        this.author = author;
    }
    public Date getCreated() {
        return created;
    }
    public void setCreated(Date created) {
        this.created = created;
    }
    }

控制器类：

package com.joydeep.springboot; 
import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.web.bind.annotation.RequestMapping; 
import org.springframework.web.bind.annotation.RestController;  

@RestController 
public class HelloCntrl { 

   @Autowired 
   Test1 test; 

   @RequestMapping("/hello")
   public String sayHi(){
      return "Hi"; 
   } 

}

初始化程序类：

package com.joydeep.springboot; 
import org.springframework.boot.SpringApplication; 
import org.springframework.boot.autoconfigure.SpringBootApplication; 

@SpringBootApplication 
public class CourseAPIStarter { 
   public static void main(String[] args) {
      SpringApplication.run(CourseAPIStarter.class); 
   } 
}

的pom.xml：

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>io.springboot</groupId>
    <artifactId>rest-course-api</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Rest service course API</name>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.2.RELEASE</version>
    </parent>
    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

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

        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derby</artifactId>
            <scope>runtime</scope>
        </dependency>

    </dependencies>
</project>

在上下文初始化期间遇到异常 - 取消刷新尝试： org.springframework.beans.factory.UnsatisfiedDependencyException：创建名为'helloCntrl'的bean时出错：通过字段'test'表示的不满意的依赖关系;嵌套异常是org.springframework.beans.factory.NoSuchBeanDefinitionException：没有'com.joydeep.springboot.Test1'类型的限定bean可用：预计至少有1个bean有资格作为autowire候选者。依赖注释{@ org.springframework.beans.factory.annotation.Autowired（required = true）}

我所指的例子来自这个链接。

https://spring.io/guides/gs/accessing-data-jpa/

Answer 1

您无需在@Repository上添加Test1注释。将这3个注释放在CourseAPIStarter类上，您的应用程序将像黄油中的热刀一样运行。

@ComponentScan(basePackages={"com.joydeep.springboot"}) 

@EntityScan(basePackages={"com.joydeep.springboot.vo"}) 

@EnableJpaRepositories(basePackages={"com.joydeep.springboot"})

@ComponentScan将扫描您的对象，并将其注册到Spring。

@EnableJpaRepositories将使您的所有Spring JPA存储库都能在您的应用程序中使用。

@EntityScan：当您在模型对象类中添加@Entity注释时，Spring将假定存在一个名为Message的表。因此，要将此类注册为Spring Entity，您需要使用此注释。

Answer 2

Spring无法找到Test1 bean，因为您忘记使用@Repository对其进行注释。您只能自动装配Spring托管类（Controller，Component，Repository，Service ecc）。试试这个：

@Repository
public interface Test1 extends CrudRepository<Message, String> { }

Answer 3

您的存储库界面Test1没有

@Repository

anotation。请添加它，并检查Test1类的位置是否有适当的组件扫描。

PS：请在下次格式化问题的代码部分。

如何自动装配spring-data CrudRepository

3 个答案: