java - 没有可用的类型 [...] 的合格 Bean

Question

我有以下结构:

网络服务

@Autowired
public FooService(@Qualifier("fooMapper1") FooBO fooBO1,
        @Qualifier("fooMapper2") FooBO fooBO2,
        @Qualifier("fooMapper3") FooBO fooBO3) {
    this.fooBO1= fooBO1;
    this.fooBO2= fooBO2;
    this.fooBO3= fooBO3;
}

配置

@Configuration
public class MapperConfig {

    @Bean("fooMapper1")
    public FooBO oneMapper(FooOneMapper mapper) {
        return new FooBO(mapper);
    }
    @Bean("fooMapper2")
    public FooBO twoMapper(FooTwoMapper mapper) {
        return new FooBO(mapper);
    }
    @Bean("fooMapper3")
    public FooBO threeMapper(FooThreeMapper mapper) {
        return new FooBO(mapper);
    }
}

FooBO

    @Autowired
    public FooBO(IFooMapper mapper) {
        this.mapper = mapper;
    }

IFooMapper是由FooOneMapper、FooTwoMapper和FooThreeMapper扩展的接口(interface)。

当我尝试运行该项目时，抛出以下消息:

Description:

Parameter 0 of constructor in ...FooBO required a single bean, but 4 were found:
    - FooOneMapper: defined in file [C:...\mapper\FooOneMapper.class]
    - FooTwoMapper: defined in file [C:...\mapper\FooTwoMapper.class]
    - FooThreeMapper: defined in file [C:...\mapper\FooThreeMapper.class]
    - IFooMapper: defined in file [C:...\mapper\IFooMapper.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

我不明白为什么 spring 与 bean 发生这种冲突，因为一切似乎都配置良好。

Answer 1

我猜您已经使用 @Component 注释对 FooBO 进行了注释。

the root package containing Spring Boot main class s is scanned to look for any @Component-annotated classes, and those classes are registered as Spring bean definitions within the container

您正在配置类中创建 bean。确保 FooBO 和 IFooMapper 未使用 @Component 或其构造型注释进行注释。

class FooBO {

    private final IFooMapper mapper;

    public FooBO(IFooMapper mapper) {
        this.mapper = mapper;
    }
}

如果由于某种原因您无法删除@Component。其他修复方法是使用 @Primary

将 IFooMapper 的实现之一标记为主要实现

@Component
@Primary
class FooOneMapper implements IFooMapper{

}

或者提供额外的数据来帮助spring解决依赖关系。

public FooBO(@Qualifier("fooThreeMapper") IFooMapper mapper) {
    this.mapper = mapper;
}