Spring boot 字段需要一個找不到類型的 bean

Question

我正在閱讀 Spring Boot 的 JPA 入門教程，我正在苦苦掙扎。 我知道這個問題有時在這里被問到（ “字段需要一個找不到類型的 bean。”使用 mongodb 的錯誤 spring restful API ）

但這些問題與我所遇到的有點不同。

結構

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

如您所見，我所有與 JPA 相關的包都與我的應用程序文件處於同一級別。 根據教程（ https://spring.io/guides/gs/accessing-data-jpa/ ）這應該工作

我的應用類

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);
    }
}

客戶資料庫

package helloWorld;


import org.springframework.data.repository.CrudRepository;

import java.util.List;

public interface CustomerRepository extends CrudRepository<Customer, Long> {

    List<Customer> findByLastName(String lastName);
}

嘗試使用@Autowired我收到

***************************
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，將scanBasePackages={"helloWorld"})到@SpringBootApplication也無濟於事，而且從我讀到的內容也不需要。

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>

鏈接到 github 項目

Answer 1

您正在排除 JPA 存儲庫的自動配置。 從application.properties刪除該行，讓 Spring 使CustomerRepository成為一個 bean 並對其進行配置。

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

Answer 2

嘗試在 Application 類上方添加@ComponentScan("package.path.to.your.repository")注釋。

- 只需確保您的存儲庫位於@ComponentScan寫入的同一包路徑中

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

         //your stuff 
    }

Answer 3

就我而言，我只是忘記將@Component添加到接口的 Impl 類！

這些錯誤可能是由於缺少一個或多個構造型注釋。

Answer 4

我從我的應用程序類更改了這個類級別注釋。

從：

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class })

到：

@SpringBootApplication

Answer 5

我遇到了同樣的問題，除了添加以下依賴項外，一切都很好。

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

而且，它對我有用

Answer 6

將包名稱更改為 helloWorld.dao.CustomerRepository 並在您創建的添加接口（也從當前包中刪除接口）並運行我知道這很奇怪，但在我的情況下運行