Spring框架：使用@Qualifier批注会引发“ NoUniqueBeanDefinitionException”（找到多个相同类型的bean）

时间：2019-09-07 17:34:12

标签： java spring spring-boot

问题

我收到错误消息

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

尝试启动我的Spring应用程序时。

这是由我创建的两个@Service类引起的，我分别创建了每个实现和接口 StorageService 。我已经在类级别本身上分别命名了@Service和@Service("service1")这两个@Service("service2")类，而我正在尝试@Autowire中的每个类@Controller }构造函数并通过在构造函数中的每个参数上直接使用@Service注释来指定所需的@Qualifier，但是我仍然收到NoUniqueBeanDefinitionException错误。

我所期望的

我只是希望Spring可以通过使用@Qualifier批注来区分这两个Bean。

代码

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

}

应用 

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();
        };
    }
}

我认为是由于FileUploadController而引发异常，但我也认为我正确使用了@Qualifier注释。

我检查过的东西

我已经从SO遍历了多个示例，但是似乎没有任何效果。

完整的异常堆栈

***************************
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

2 个答案:

答案 0 :(得分：1)

我认为您应该将@Qualifier添加到CommandLineRunner：

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

答案 1 :(得分：-1)

这个问题被问了很长时间，并且也得到了解决。但是我想告诉作者一个大错误，它阻止了他找到根本原因。

根据堆栈跟踪，它告诉问题是在init方法中，而不是作者认为的在Controller中。这张错误的支票使他远离了根本原因。

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]
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