一、循环依赖问题

APPLICATION FAILED TO START

Description:

The dependencies of some of the beans in the application context form a cycle:

┌─────┐
| springSecurityConfig (field private XXXX.config.MyauthenticationProvider XXXX.config.SpringSecurityConfig.myauthenticationProvider)
↑ ↓
| myauthenticationProvider (field private org.springframework.security.crypto.password.PasswordEncoder XXXX.config.MyauthenticationProvider.passwordEncoder)
└─────┘

Action:

Relying upon circular references is discouraged and they are prohibited by default. Update your application to remove the dependency cycle between beans. As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.

进程已结束，退出代码为 0

二、背景说明

最近也没有啥变更啊，有的就是因为客户漏洞扫描的时候，反馈了说我们的Spring框架出问题了，第一直接就是SpringBoot的版本有问题，要修复，于是升级了版本如下，这一升级，好啦，就出现了上面的问题了。
漏洞扫描报告

<parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.6.7</version>
      <relativePath/>
</parent>

底层默认的Spring版本是

<spring-framework.version>5.3.19</spring-framework.version>

三、问题原因

3.1 在SpringSecurityConfig注入MyAuthenticationProvider

@Autowired
private MyAuthenticationProvider myAuthenticationProvider;

3.2 在SpringSecurityConfig声明一个Bean，PasswordEncoder

@Bean
public PasswordEncoder passwordEncoder() {
     return new BCryptPasswordEncoder();
}

3.2 在MyAuthenticationProvider 又注入了PasswordEncoder

@Component
public class MyAuthenticationProvider implements AuthenticationProvider, UserDetailsService {
    @Autowired
    private UserService userService;
    @Autowired
    private UserDao userDao;
    @Autowired
    private PasswordEncoder passwordEncoder;

四、问题解决

循环引用主要是因为会导致Spring不知道该先创建哪个Bean才会被禁用的，可以使用@Lazy注解指定某个Bean进行懒加载就可以优雅解决该问题。

@Component
public class MyAuthenticationProvider implements AuthenticationProvider, UserDetailsService {

    @Autowired
    private UserService userService;

    @Autowired
    private UserDao userDao;

    @Lazy
    @Autowired
    private PasswordEncoder passwordEncoder;