我正在学习如何使用spring security来构建登录功能，我得到了如下错误“无效的用户名或密码”：
原因：java.lang.NullPointerException：无法调用“com.thang.repository.AccountRepository.findByUsername（String）”，因为“this.accountRepository”在com.thang.service.CustomAccountDetailsService.loadUserByUsername（CustomAccountDetailsService.java：27）~[classes/：na] at org.springframework.security.authentication.dao.DaoAuthenticationProvider.retrieveUser（DaoAuthenticationProvider.java：103）~[spring-security-core-6.1.1.jar：6.1.1]为null...省略60个公共帧
我试着在谷歌上找到修复它的方法，但它不起作用，希望你能帮助我x1c 0d1x
Account.java

package com.thang.entity;

import java.util.Set;

import jakarta.persistence.*;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name= "users")
public class Account {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    
    @Column(nullable = false, unique = true)
    private String username;
    
    @Column(nullable = false, unique = true)
    private String email;
    
    @Column(nullable = false)
    private String password;
    
    public Account(String name, String username, String email, String password, Set<Role> roles) {
        super();
        this.name = name;
        this.username = username;
        this.email = email;
        this.password = password;
        this.roles = roles;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Set<Role> getRoles() {
        return roles;
    }

    public void setRoles(Set<Role> roles) {
        this.roles = roles;
    }

    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(name = "users_roles",
    joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"),
        inverseJoinColumns = @JoinColumn(name = "role_id", referencedColumnName = "id")
    )
    private Set<Role> roles;
    
}

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AccountRepository.java

package com.thang.repository;

import java.util.Optional;

import org.springframework.data.jpa.repository.JpaRepository;

import com.thang.entity.Account;

public interface AccountRepository extends JpaRepository<Account, Long>{

    Optional<Account> findByUsername(String username);

    Boolean existsByEmail(String email);

    Optional<Account> findByUsernameOrEmail(String username, String email);

    boolean existsByUsername(String username);
    
}

型
CustomAccountDetailsService.java

package com.thang.service;

import lombok.AllArgsConstructor;

import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

import com.thang.entity.Account;
import com.thang.repository.AccountRepository;

import java.util.Set;
import java.util.stream.Collectors;

@Service
@AllArgsConstructor
public class CustomAccountDetailsService implements UserDetailsService {

    private AccountRepository accountRepository;

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        
        Account account = accountRepository.findByUsername(username)
                .orElseThrow(() -> new UsernameNotFoundException("User not exists by Username"));

        Set<GrantedAuthority> authorities = account.getRoles().stream()
                .map((role) -> new SimpleGrantedAuthority(role.getName()))
                .collect(Collectors.toSet());

        return new org.springframework.security.core.userdetails.User(
                username,
                account.getPassword(),
                authorities
        );
    }
   
}

型
login.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Login</title>
 <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css"
          rel="stylesheet"
          integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC"
          crossorigin="anonymous">
</head>
<body>
    <nav class="navbar navbar-expand-lg navbar-dark bg-dark">
        <div class="container-fluid">
            <a class="navbar-brand" th:href="@{/index}">Login System</a>
            <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
                <span class="navbar-togger-icon"></span>
            </button>
        </div>
    </nav>
    <br /><br />
    <div class="container">
        <div class="row">
            <div class="col-md-6 offset-md-3">
                <div th:if="${param.error}">
                    <div class="alert alert-danger">Invalid Username or Password</div>
                </div>
                <div th:if="${param.logout}">
                    <div class="alert alert-success">You have been logout.</div>
                </div>
                
                <div class="card">
                    <div class="card-header">
                        <h2 class="text-center">Login Form</h2>
                    </div>
                    <div class="card-body">
                        <form method="post" role="form" th:action="@{/login}" class="form-horizontal">
                            <div class="form-group mb3">
                                <label>User Name</label>
                                <input
                                    type="text"
                                    id="username"
                                    name="username"
                                    class="form-control"
                                    placeholder="Enter Username"                                
                                />
                            </div>
                            
                            <div class="form-group mb3">
                                <label>Password</label>
                                <input
                                    type="password"
                                    id="password"
                                    name="password"
                                    class="form-control"
                                    placeholder="Enter password"                                
                                />
                            </div>
                            <br>
                            <div class="form-group mb-3">
                                <button type="submit" class="btn btn-primary">Submit</button>
                            </div>
                        </form>
                    </div>
                </div>
            </div>
        </div>
    </div>
</body>
</html>

型
SecurityConfig.java

package com.thang.security;

import lombok.AllArgsConstructor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.config.annotation.authentication.configuration.AuthenticationConfiguration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.SecurityFilterChain;
import org.springframework.security.web.util.matcher.AntPathRequestMatcher;

import static org.springframework.security.config.Customizer.*;

@Configuration
@AllArgsConstructor
public class SecurityConfig{

    @SuppressWarnings("unused")
    private UserDetailsService userDetailsService;

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

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http.csrf(withDefaults())
                .authorizeHttpRequests((authorize) ->
                        authorize.anyRequest().authenticated()
                ).formLogin(
                form -> form
                        .loginPage("/login")
                        .loginProcessingUrl("/login")
                        .defaultSuccessUrl("/handover")
                        .permitAll()
        ).logout(
                logout -> logout
                        .logoutRequestMatcher(new AntPathRequestMatcher("/logout"))
                        .permitAll()
        );
        return http.build();
    }

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

型