1. AuthenticationManager無法自動注入

在實現AbstractAuthenticationProcessingFilter重寫以使用者名稱、密碼認證時，需要顯示注入AuthenticationManager，不然會報如下錯誤：

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'usernamePasswordAuthenticationFilter' defined in class path resource 
           [com/wj/springbootdemo/modules/auth/security/SecurityConfig.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: authenticationManager must be specified
 

解決辦法，顯示注入AuthenticationManager：

@Bean
@Override
public AuthenticationManager authenticationManagerBean() throws Exception {
    return super.authenticationManagerBean();
}

然後注入到UsernamePasswordAuthenticationFilter裡：

@Bean
public UsernamePasswordAuthenticationFilter usernamePasswordAuthenticationFilter
 
() throws Exception {
       UsernamePasswordAuthenticationFilter filter=new UsernamePasswordAuthenticationFilter();
       filter.setAuthenticationManager(authenticationManagerBean());
       return filter;
}

2.需要指定密碼加密方式

在使用Spring Security 5.x登陸頁面進行登陸時，後端會報錯：There is no PasswordEncoder mapped for the id “null”，因為5.x版本新增了多種密碼加密方式，必須指定一種，比如這樣解決：

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

下列加密方式供參考，選取一種即可：

bcrypt - BCryptPasswordEncoder (Also used for encoding) 

ldap - LdapShaPasswordEncoder 

MD4 - Md4PasswordEncoder 

MD5 - new MessageDigestPasswordEncoder("MD5") 

noop - NoOpPasswordEncoder 

pbkdf2 - Pbkdf2PasswordEncoder 

scrypt - SCryptPasswordEncoder 

SHA-1 - new MessageDigestPasswordEncoder("SHA-1") 

SHA-256 - new MessageDigestPasswordEncoder("SHA-256") 

sha256 - StandardPasswordEncoder