Spring通过构造函数参数表达不满足的依赖关系，索引类型为0

完整的消息是

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: 
    Error creating bean with name 'userRepositoryUserDetailsService' defined in file 
    [/Users/tdaley/apache-tomcat-8.0.12/wtpwebapps/cloud-management/WEB-INF/classes/
       org/cru/cloud/management/security/UserRepositoryUserDetailsService.class]: 
    Unsatisfied dependency expressed through constructor argument with index 0 of type 
[org.cru.cloud.management.data.UserRepository]: : No qualifying bean of 
    type [org.cru.cloud.management.data.UserRepository] found for dependency: 
        expected at least 1 bean which qualifies 
        as autowire candidate for this dependency. 
     Dependency annotations: {}; 
nested exception is 
    org.springframework.beans.factory.NoSuchBeanDefinitionException: 
       No qualifying bean of type [org.cru.cloud.management.data.UserRepository] found 
       for dependency: expected at least 1 bean 
       which qualifies as autowire candidate for this dependency. 
     Dependency annotations: {}

我正在使用 Java 配置。以下代码段来自spring boot教程gs-spring-security-3.2：

package org.cru.cloud.management.security;

import java.util.Collection;

import org.cru.cloud.management.data.User;
import org.cru.cloud.management.data.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.AuthorityUtils;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

@Service
public class UserRepositoryUserDetailsService implements UserDetailsService {
    private final UserRepository userRepository;

    @Autowired
    public UserRepositoryUserDetailsService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Override
    public UserDetails loadUserByUsername(String username)
            throws UsernameNotFoundException {
        User user = userRepository.findByEmail(username);
        if(user == null) {
            throw new UsernameNotFoundException("Could not find user " + username);
        }
        return new UserRepositoryUserDetails(user);
    }

    private final static class UserRepositoryUserDetails extends User implements UserDetails {    

        private UserRepositoryUserDetails(User user) {
            super(user);
        }

        @Override
        public Collection<? extends GrantedAuthority> getAuthorities() {
            return AuthorityUtils.createAuthorityList("ROLE_USER");
        }

        @Override
        public String getUsername() {
            return getEmail();
        }

        @Override
        public boolean isAccountNonExpired() {
            return true;
        }

        @Override
        public boolean isAccountNonLocked() {
            return true;
        }

        @Override
        public boolean isCredentialsNonExpired() {
            return true;
        }

        @Override
        public boolean isEnabled() {
            return true;
        }

        private static final long serialVersionUID = 5639683223516504866L;
    }
}

public interface UserRepository extends CrudRepository<User, Long>
{
    User findByEmail(String email);
}

关于如何解决这个问题的建议？

你有吗@EnableJpaRepositories http://docs.spring.io/spring-data/jpa/docs/current/api/org/springframework/data/jpa/repository/config/EnableJpaRepositories.html您的配置类中的某处注释以及扫描设置是否正确？默认情况下，带注释的类或接口所在的包将成为存储库扫描的基础包。您可以通过为 basePackages（甚至更好 - basePackageClasses）属性设置一个值来控制它。

您可以使用 Spring Tools Suite 检查在您的上下文中声明了哪些 bean（存储库应该在 Spring Elements > Beans > Spring Data Repositories 下可见）。