关于OAuth2AuthServerConfig中passwordEncoder和authenticationManager注入顺序的问题

来源：4-5 搭建OAuth2认证服务器

落尽余辉

2019-09-15

我在跟着视频敲代码的时候，将passwordEncoder写在authenticationManager之前：

@Configuration
@EnableAuthorizationServer
public class OAuth2AuthServerConfig extends AuthorizationServerConfigurerAdapter {

    @Autowired
    private PasswordEncoder passwordEncoder;

    @Autowired
    private AuthenticationManager authenticationManager;

其他的代码与老师写的一样，结果在启动时就出现了：

Error creating bean with name 'OAuth2AuthServerConfig': Unsatisfied dependency expressed through field 'passwordEncoder'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'OAuth2WebSecurityConfig': Unsatisfied dependency expressed through field 'userDetailsService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userDetailServiceImpl': Unsatisfied dependency expressed through field 'passwordEncoder'; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'passwordEncoder': Requested bean is currently in creation: Is there an unresolvable circular reference?

"Error creating bean with name ‘passwordEncoder’: Requested bean is there an unresolvable circular reference?"
看了一下感觉像是UserDetailServiceImpl和OAuth2WebSecurityConfig这两个类出现的循环引用？
有两种解决方法
一是将OAuth2AuthServerConfig中的注入顺序替换下，按照老师的写法

    @Autowired
    private AuthenticationManager authenticationManager;
    
    @Autowired
    private PasswordEncoder passwordEncoder;

二是移除passwordEncoder注入，改为本地变量直接使用

@Component
public class UserDetailServiceImpl implements UserDetailsService {

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        PasswordEncoder passwordEncoder = new BCryptPasswordEncoder();
        return User.withUsername(username)
                .password(passwordEncoder.encode("123456"))
                .authorities("ROLE_ADMIN").build();
    }
}

搜了一圈找到类似的问题，却也没有正儿八经的解决思路，大概能知道是passwordEncoder注入的问题，但不知道究竟为什么会导致这种情况的发生，希望老师能解答一下，
非常感谢(｡◕◡◕｡)ﾉ

写回答

6回答