Spring Boot 3.0.6创建用户时PasswordEncoder空指针异常求助

错误信息 #

{"message": "Cannot invoke \"org.springframework.security.crypto.password.PasswordEncoder.encode(java.lang.CharSequence)\" because \"this.passwordEncoder\" is null", "path": "/auth/nuevo"}

我的MainSecurity代码 #

@Configuration
@EnableWebSecurity
@EnableMethodSecurity
public class MainSecurity {

    @Autowired
    UserDetailsImpl userDetailsServiceImpl;

    @Autowired
    JwtEntryPoint jwtEntryPoint;

    @Bean
    public JwtTokenFilter jwtTokenFilter() {
        return new JwtTokenFilter();
    }

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

    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(userDetailsServiceImpl).passwordEncoder(passwordEncoder());
    }

    @Bean
    public AuthenticationManager authenticationManager(AuthenticationConfiguration authenticationConfiguration)
            throws Exception {
        return authenticationConfiguration.getAuthenticationManager();
    }

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http.cors().and().csrf().disable()
                .exceptionHandling().authenticationEntryPoint(jwtEntryPoint).and()
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS).and()
                .authorizeHttpRequests()
                .requestMatchers("/**").permitAll()
                .anyRequest().authenticated();
            http
.addFilterBefore(jwtTokenFilter()
, UsernamePasswordAuthenticationFilter.class);

        return http.build();
    }
}

解决方案 #

1. 修复用户创建Service的PasswordEncoder注入 #

空指针的核心原因是创建用户的逻辑中未正确注入PasswordEncoder Bean，导致调用encode方法时对象为空。确保用户Service通过构造注入（Spring 3.x推荐方式）引入PasswordEncoder：

@Service
public class UserService {
    private final PasswordEncoder passwordEncoder;
    private final UserRepository userRepository;

    public UserService(PasswordEncoder passwordEncoder, UserRepository userRepository) {
        this.passwordEncoder = passwordEncoder;
        this.userRepository = userRepository;
    }

    public User createUser(UserDto userDto) {
        User user = new User();
        user.setUsername(userDto.getUsername());
        // 使用注入的PasswordEncoder加密密码
        user.setPassword(passwordEncoder.encode(userDto.getPassword()));
        // 其他字段赋值
        return userRepository.save(user);
    }
}

2. 移除已弃用的configure方法 #

Spring Boot 3.x中configure(AuthenticationManagerBuilder auth)方法已被弃用，框架会自动关联你定义的PasswordEncoder和UserDetailsService Bean，无需手动配置。修改后的MainSecurity代码：

@Configuration
@EnableWebSecurity
@EnableMethodSecurity
public class MainSecurity {

    private final UserDetailsImpl userDetailsServiceImpl;
    private final JwtEntryPoint jwtEntryPoint;

    // 构造注入替代@Autowired（Spring 3.x推荐写法）
    public MainSecurity(UserDetailsImpl userDetailsServiceImpl, JwtEntryPoint jwtEntryPoint) {
        this.userDetailsServiceImpl = userDetailsServiceImpl;
        this.jwtEntryPoint = jwtEntryPoint;
    }

    @Bean
    public JwtTokenFilter jwtTokenFilter() {
        return new JwtTokenFilter();
    }

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

    @Bean
    public AuthenticationManager authenticationManager(AuthenticationConfiguration authenticationConfiguration)
            throws Exception {
        return authenticationConfiguration.getAuthenticationManager();
    }

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http.cors().and().csrf().disable()
                .exceptionHandling().authenticationEntryPoint(jwtEntryPoint).and()
                .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS).and()
                .authorizeHttpRequests(auth -> auth
                        .requestMatchers("/**").permitAll()
                        .anyRequest().authenticated())
                .addFilterBefore(jwtTokenFilter(), UsernamePasswordAuthenticationFilter.class);

        return http.build();
    }
}

3. 验证UserDetailsImpl的配置 #

确保UserDetailsImpl类正确实现UserDetailsService接口，并且添加了@Service注解被Spring容器管理。

内容的提问来源于stack exchange，提问作者Programmer-G