Spring Boot 应用程序启动失败，找不到 bean

Question

我的 Spring Boot 应用程序将无法启动，因为找不到 bean。 我做了很多调查，并尝试过很多次尝试解决这个问题，但没有一个奏效。 以下是常见的问题（以及为什么他们没有为我解决它）。 任何帮助或建议将不胜感激。

问题的潜在原因

1. 没有在正确的位置声明主类

   我的文件夹结构如下所示。 我相信这是结构应该避免任何NoSuchBeanDefinitionException问题。 在这里可能还值得一提的是，这不是我的整个项目。 只是我认为与此问题相关的文件。

   文件夹结构

   src/ ├── main/ │ └── java/ | ├── mygroup.tqbcbackend/ | | └── TqbcBackendApplication.java | ├── mygroup.tqbcbackend.model/ | | └── Team.java | ├── mygroup.tqbcbackend.controller/ | | └── TeamController.java | └── mygroup.tqbcbackend.repository/ | └── TeamRepository.java └── resources/ └── application.properties

2. 类没有用 @Repository 等注解声明

   我的代码在下面，我不相信这是真的

3. 这个答案建议从上面的private TeamRepository teamRepository; 在TeamController.java

   这确实导致应用程序启动，但是调用teamRepository.findAll();时返回了java.lang.NullPointerException ；

错误

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.6.3)

2022-06-20 22:54:18.006  INFO 23052 --- [  restartedMain] m.tqbcbackend.TqbcBackendApplication     : Starting TqbcBackendApplication using Java 11.0.15 on OD with PID 23052 (C:\Dev\TheQBCarousel\tqbc-backend\target\classes started by odern in C:\Dev\TheQBCarousel\tqbc-backend)
2022-06-20 22:54:18.007  INFO 23052 --- [  restartedMain] m.tqbcbackend.TqbcBackendApplication     : No active profile set, falling back to default profiles: default
2022-06-20 22:54:18.065  INFO 23052 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2022-06-20 22:54:18.067  INFO 23052 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2022-06-20 22:54:19.613  INFO 23052 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2022-06-20 22:54:19.623  INFO 23052 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2022-06-20 22:54:19.624  INFO 23052 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.56]     
2022-06-20 22:54:19.867  INFO 23052 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2022-06-20 22:54:19.867  INFO 23052 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1800 ms
2022-06-20 22:54:20.117  WARN 23052 --- [  restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'teamController': Unsatisfied dependency expressed through field 'teamRepository'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'mygroup.tqbcbackend.repository.TeamRepository' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2022-06-20 22:54:20.122  INFO 23052 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]

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

Description:

Field teamRepository in mygroup.tqbcbackend.controller.TeamController required a bean of type 'mygroup.tqbcbackend.repository.TeamRepository' that could not be found.

The injection point has the following annotations:
        - @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'mygroup.tqbcbackend.repository.TeamRepository' in your configuration.

TeamController.java

package mygroup.tqbcbackend.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import mygroup.tqbcbackend.model.Team;
import mygroup.tqbcbackend.repository.TeamRepository;

@CrossOrigin(origins = "*")
@RestController
@RequestMapping("/api/v1/teams")
public class TeamController {

    @Autowired
    private TeamRepository teamRepository;
    
    // Get all teams
    @GetMapping("/all")
    public List<Team> getAllTeams() {
        return teamRepository.findAll();
    }
    
    // Get all active teams
    @GetMapping("/active")
    public List<Team> getAllActiveTeams() {
        return teamRepository.findByIsActiveTrue();
    } 
}

TeamRepository.java

package mygroup.tqbcbackend.repository;

import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import mygroup.tqbcbackend.model.Team;

@Repository
public interface TeamRepository extends JpaRepository<Team,String>{
    
    public List<Team> findByIsActiveTrue();

}

TqbcBackendApplication.java

package mygroup.tqbcbackend;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class TqbcBackendApplication {

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

}

应用程序属性

####### Data-Source Properties #######
spring.datasource.url=jdbc:mysql://localhost:3306/the_qb_carousel?useSSL=false&allowPublicKeyRetrieval=true
spring.datasource.username=root
spring.datasource.password=mypassword
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

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


###### JPA Properties ######
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect

# Stops SQL column names being automatically renamed to snake case
spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

spring.jpa.hibernate.ddl-auto=update
# 
spring.jpa.properties.hibernate.jdbc.batch_size=16

logging.level.org.hibernate.persister.entity=ERROR


#logging.level.org.hibernate.SQL=DEBUG
#logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE
#logging.level.org.hibernate.type=TRACE

###### App Properties ######
tqdm.app.jwtSecret= VerySecretKey
tqdm.app.jwtExpirationMs= 86400000
tqdm.app.frontEndURL=http://localhost:8081

###### Email Properties ######
spring.mail.host = smtp.gmail.com
spring.mail.port = 587
spring.mail.properties.mail.smtp.starttls.enable = true
spring.mail.username = mail@gmail.com
spring.mail.password = password
spring.mail.properties.mail.smtp.starttls.required = true
spring.mail.properties.mail.smtp.auth = true
spring.mail.properties.mail.smtp.connectiontimeout = 5000
spring.mail.properties.mail.smtp.timeout = 5000
spring.mail.properties.mail.smtp.writetimeout = 5000

Answer 1

嗯......，这应该工作？ 好吧，您可以强制 Spring 查找存储库的特定包。 在您的主服务器上尝试@EnableJpaRepositories("mygroup.tqbcbackend.repository") 。

从Spring Boot Documetation的示例 12 中窃取