Spring boot Field 需要一个找不到类型的 bean

Question

我正在努力学习 Spring Boot 的 JPA 入门教程。 我知道这个问题有时在这里被问到 ('Field required a bean of type that could not be found.' error spring restful API using mongodb)

但是这些问题和我的有点不同。

结构

java
  |
  helloWorld
  |
  web/ -- HelloWorldController
  Application
  Customer
  CustomerRepository
  ServletInitializer

如您所见，我所有与 JPA 相关的包都与我的应用程序文件处于同一级别。根据教程 (https://spring.io/guides/gs/accessing-data-jpa/) 这应该可以工作

我的应用类

package helloWorld;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
public class Application extends SpringBootServletInitializer {

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

    @Autowired
    CustomerRepository customerRepository;

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }
}

客户资料库

package helloWorld;


import org.springframework.data.repository.CrudRepository;

import java.util.List;

public interface CustomerRepository extends CrudRepository<Customer, Long> {

    List<Customer> findByLastName(String lastName);
}

当我尝试使用@Autowired 时，我收到了

***************************
APPLICATION FAILED TO START
***************************

Description:

Field customerRepository in helloWorld.Application required a bean of type 'helloWorld.CustomerRepository' that could not be found.


Action:

Consider defining a bean of type 'helloWorld.CustomerRepository' in your configuration.

此外，将scanBasePackages={"helloWorld"}) 添加到@SpringBootApplication 并没有帮助，从我所读到的内容来看，它也应该不需要。

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>helloWorld.com.example</groupId>
    <artifactId>helloWorld</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>fireCommerce</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</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>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</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>
            <plugin>
                <groupId>com.microsoft.azure</groupId>
                <artifactId>azure-webapp-maven-plugin</artifactId>
                <version>1.1.0</version>
                <configuration>
                    <resourceGroup>maven-projects</resourceGroup>
                    <appName>${project.artifactId}-${maven.build.timestamp}</appName>
                    <region>westus</region>
                    <javaVersion>1.8</javaVersion>
                    <deploymentType>war</deploymentType>
                </configuration>
            </plugin>
        </plugins>
    </build>


</project>

link to the github project

Answer 1

您正在排除 JPA 存储库的自动配置。从application.properties 中删除该行，让Spring 将CustomerRepository 制作为一个bean 并对其进行配置。

spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration

Answer 2

就我而言，我只是忘记将@Component 添加到接口的 Impl 类中！

这些错误可能是由于缺少一个或多个刻板印象注释。

Answer 3

我从我的应用程序类中更改了这个类级别注释。

发件人：

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class })

收件人：

@SpringBootApplication

Answer 4

尝试在Application类上方添加@ComponentScan("package.path.to.your.repository")注解。

- 只需确保您的存储库与写入的包路径相同 @ComponentScan

    @SpringBootApplication
    @ComponentScan("helloworld")
    public class Application extends SpringBootServletInitializer {

         //your stuff 
    }

Answer 5

我遇到了同样的问题，除了添加以下依赖项外，一切都很好。

<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>2.4.2</version>

而且，它对我有用