配置含自定义用户与密码编码器的Spring Security时遇错误

原配置代码 #

@Configuration
public class SpringSecurityConfiguration {

    
    //InMemoryUserDetailsManager(UserDetails... users)
    
        
    @Bean
    public InMemoryUserDetailsManager createUserDetailsManager() {
        
        Function<String, String> passwordEncoder
                = input -> passwordEncoder().encode(input);
        
        UserDetails userDetails = User.builder()
                                    .passwordEncoder(passwordEncoder)
                                    .username("abc")
                                    .password("123")
                                    .roles("USER","ADMIN")
                                    .build();
        
        return InMemoryUserDetailsManager(userDetails);
    }

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

}

报错信息 #

Error:The method InMemoryUserDetailsManager(UserDetails) is undefined for the type SpringSecurityConfiguration
Error:The method BCryptPasswordEncoder() is undefined for the type SpringSecurityConfiguration

错误原因与修复步骤 #

这两个错误的核心是把类当成当前类的方法调用了，正确做法是用new关键字实例化对应类，同时要确保导入了正确的Spring Security依赖包：

1. 修复InMemoryUserDetailsManager实例化
   原代码中直接写InMemoryUserDetailsManager(userDetails)是错误的，这是类的构造方法，需要用new创建实例，改为：

   return new InMemoryUserDetailsManager(userDetails);
   

2. 修复BCryptPasswordEncoder实例化
   同理，BCryptPasswordEncoder()是类的构造方法，需要添加new关键字，改为：

   return new BCryptPasswordEncoder();
   

3. 补充必要的导入语句
   在类的顶部添加以下导入，确保所有用到的类都能被识别：

   import org.springframework.context.annotation.Bean;
   import org.springframework.context.annotation.Configuration;
   import org.springframework.security.core.userdetails.User;
   import org.springframework.security.core.userdetails.UserDetails;
   import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
   import org.springframework.security.crypto.password.PasswordEncoder;
   import org.springframework.security.provisioning.InMemoryUserDetailsManager;
   import java.util.function.Function;
   

修复后的完整代码 #

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;
import java.util.function.Function;

@Configuration
public class SpringSecurityConfiguration {

    @Bean
    public InMemoryUserDetailsManager createUserDetailsManager() {
        
        Function<String, String> passwordEncoder
                = input -> passwordEncoder().encode(input);
        
        UserDetails userDetails = User.builder()
                                    .passwordEncoder(passwordEncoder)
                                    .username("abc")
                                    .password("123")
                                    .roles("USER","ADMIN")
                                    .build();
        
        return new InMemoryUserDetailsManager(userDetails);
    }

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

}

内容的提问来源于stack exchange，提问作者Lamda Function