使用@Qualifier 注释抛出“NoUniqueBeanDefinitionException”（发现多个相同类型的bean）

Question

Problem

I'm receiving the error

Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'hello.storage.StorageService' available: expected single matching bean but found 2: service2,service1

when attempting to start my Spring application.

This is caused by two @Service classes I've created that each implement and interface I've created, StorageService . I've named both of the @Service classes on the class level itself, @Service("service1") and @Service("service2") , and I'm trying to @Autowire each class in a @Controller constructor and specifying the @Service I want by using the @Qualifier annotation directly on each parameter in the constructor but I am still receiving the NoUniqueBeanDefinitionException error.

What I expect

I just expect Spring to be able to differentiate between the two Beans by using the @Qualifier annotation.

Code

StorageService

package hello.storage;

import org.springframework.core.io.Resource;
import org.springframework.web.multipart.MultipartFile;

import java.nio.file.Path;
import java.util.stream.Stream;

public interface StorageService {

    void init();

    void store(MultipartFile file);

    Stream<Path> loadAll();

    Path load(String filename);

    Resource loadAsResource(String filename);

    void deleteAll();

}

FileSystemStorageService

package hello.storage;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.core.io.Resource;
import org.springframework.core.io.UrlResource;
import org.springframework.stereotype.Service;
import org.springframework.util.FileSystemUtils;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.net.MalformedURLException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Stream;

@Service("service1")
public class FileSystemStorageService implements StorageService {

    private final Path rootLocation;

    @Autowired
    public FileSystemStorageService(StorageProperties properties) {
        this.rootLocation = Paths.get(properties.getLocation());
    }

    @Override
    public void store(MultipartFile file) {
        try {
            if (file.isEmpty()) {
                throw new StorageException("Failed to store empty file " + file.getOriginalFilename());
            }
            Files.copy(file.getInputStream(), this.rootLocation.resolve(file.getOriginalFilename()));
        } catch (IOException e) {
            throw new StorageException("Failed to store file " + file.getOriginalFilename(), e);
        }
    }

    @Override
    public Stream<Path> loadAll() {
        try {
            return Files.walk(this.rootLocation, 1)
                    .filter(path -> !path.equals(this.rootLocation))
                    .map(path -> this.rootLocation.relativize(path));
        } catch (IOException e) {
            throw new StorageException("Failed to read stored files", e);
        }

    }

    @Override
    public Path load(String filename) {
        return rootLocation.resolve(filename);
    }

    @Override
    public Resource loadAsResource(String filename) {
        try {
            Path file = load(filename);
            Resource resource = new UrlResource(file.toUri());
            if(resource.exists() || resource.isReadable()) {
                return resource;
            }
            else {
                throw new StorageFileNotFoundException("Could not read file: " + filename);

            }
        } catch (MalformedURLException e) {
            throw new StorageFileNotFoundException("Could not read file: " + filename, e);
        }
    }

    @Override
    public void deleteAll() {
        FileSystemUtils.deleteRecursively(rootLocation.toFile());
    }

    @Override
    public void init() {
        try {
            Files.createDirectory(rootLocation);
        } catch (IOException e) {
            throw new StorageException("Could not initialize storage", e);
        }
    }
}

AltFileSystemStorageService

package hello.storage;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.core.io.Resource;
import org.springframework.core.io.UrlResource;
import org.springframework.stereotype.Service;
import org.springframework.util.FileSystemUtils;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.net.MalformedURLException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Stream;

@Service("service2")
public class AltFileSystemStorageService implements StorageService {

    // Exactly the same as "FileSystemStorageService" this is just for testing/learning
}

FileUploadController

package hello;

import java.io.IOException;
import java.util.stream.Collectors;

import hello.storage.AltFileSystemStorageService;
import hello.storage.FileSystemStorageService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

import hello.storage.StorageFileNotFoundException;
import hello.storage.StorageService;

@Controller
public class FileUploadController {

    private final StorageService storageService;
    private final StorageService altStorageService;

    @Autowired
    public FileUploadController(@Qualifier("service1") FileSystemStorageService storageService,
                                @Qualifier("service2") AltFileSystemStorageService altStorageService)
    {
        this.storageService = storageService;
        this.altStorageService = altStorageService;
    }

    // Controller specific methods

}

Application

package hello;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;

import hello.storage.StorageProperties;
import hello.storage.StorageService;

@SpringBootApplication
@EnableConfigurationProperties(StorageProperties.class)
public class Application {

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

    @Bean
    CommandLineRunner init(StorageService storageService) {
        return (args) -> {
            storageService.deleteAll();
            storageService.init();
        };
    }
}

I believe the exception is being thrown because of the FileUploadController but I also thought I was using the @Qualifier annotation correctly.

What I've checked

I've gone over multiple examples from SO but nothing seems to be working.

• Autowiring of beans in spring boot with @Qualifier annotation

• @Qualifier Annotation in Spring is not working

• Spring @Autowired and @Qualifier [closed]

Complete Exception Stack

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

Description:

Parameter 0 of method init in hello.Application required a single bean, but 2 were found:
    - service2: defined in file [/UploadFiles/initial/target/classes/hello/storage/AltFileSystemStorageService.class]
    - service1: defined in file [/UploadFiles/initial/target/classes/hello/storage/FileSystemStorageService.class]


Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

[WARNING] 
java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at org.springframework.boot.maven.AbstractRunMojo$LaunchRunner.run(AbstractRunMojo.java:542)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'init' defined in hello.Application: Unsatisfied dependency expressed through method 'init' parameter 0; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'hello.storage.StorageService' available: expected single matching bean but found 2: service2,service1
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:769)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:509)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1321)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1160)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:742)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:389)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:311)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1213)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1202)
    at hello.Application.main(Application.java:17)
    ... 6 more
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'hello.storage.StorageService' available: expected single matching bean but found 2: service2,service1
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveNotUnique(DependencyDescriptor.java:221)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1229)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1171)
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857)
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760)
    ... 25 more
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 5.838 s
[INFO] Finished at: 2019-09-07T13:21:10-04:00
[INFO] Final Memory: 34M/120M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.1.6.RELEASE:run (default-cli) on project gs-uploading-files: An exception occurred while running. null: InvocationTargetException: Error creating bean with name 'init' defined in hello.Application: Unsatisfied dependency expressed through method 'init' parameter 0; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'hello.storage.StorageService' available: expected single matching bean but found 2: service2,service1 -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

Answer 1

I think you should add @Qualifier to the CommandLineRunner :

@Bean
CommandLineRunner init(@Qualifier("service1") StorageService storageService)

Answer 2

This question was asked for a long time, and was resolved as well. But I'd like to tell the big mistake of the author, it prevented him finding the root cause.

According to stack trace, it told issue was in init method, not in Controller as the author considered. This wrong check took him far away to the root cause.

Parameter 0 of method init in hello.Application required a single bean, but 2 were found:
    - service2: defined in file [/UploadFiles/initial/target/classes/hello/storage/AltFileSystemStorageService.class]
    - service1: defined in file [/UploadFiles/initial/target/classes/hello/storage/FileSystemStorageService.class]