本文介绍如何使用Spring Security和JWT构建安全的登录认证系统：

  1. Spring Security核心概念
  2. JWT原理及结构
  3. 项目搭建步骤
  4. 安全配置类实现
  5. JWT工具类开发
  6. 认证过滤器实现
  7. 完整示例代码

1. 添加依赖

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<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-api</artifactId>
    <version>0.11.5</version>
</dependency>

2. 安全配置类

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@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable()
            .authorizeRequests()
            .antMatchers("/auth/login").permitAll()
            .anyRequest().authenticated()
            .and()
            .addFilter(new JwtAuthenticationFilter(authenticationManager()));
    }
}

3. JWT工具类

创建JWT工具类用于生成和验证token：

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@Component
public class JwtTokenUtil {

    private static final String SECRET = "your-secret-key";
    private static final long EXPIRATION = 86400000; // 24小时
    private static final String TOKEN_PREFIX = "Bearer ";
    private static final String HEADER_STRING = "Authorization";

    public String generateToken(UserDetails userDetails) {
        Map<String, Object> claims = new HashMap<>();
        return createToken(claims, userDetails.getUsername());
    }

    private String createToken(Map<String, Object> claims, String subject) {
        return Jwts.builder()
                .setClaims(claims)
                .setSubject(subject)
                .setIssuedAt(new Date())
                .setExpiration(new Date(System.currentTimeMillis() + EXPIRATION))
                .signWith(SignatureAlgorithm.HS512, SECRET)
                .compact();
    }

    public String getUsernameFromToken(String token) {
        return getClaimFromToken(token, Claims::getSubject);
    }

    public Date getExpirationDateFromToken(String token) {
        return getClaimFromToken(token, Claims::getExpiration);
    }

    private <T> T getClaimFromToken(String token, Function<Claims, T> claimsResolver) {
        final Claims claims = getAllClaimsFromToken(token);
        return claimsResolver.apply(claims);
    }

    private Claims getAllClaimsFromToken(String token) {
        return Jwts.parser()
                .setSigningKey(SECRET)
                .parseClaimsJws(token)
                .getBody();
    }

    public Boolean validateToken(String token, UserDetails userDetails) {
        final String username = getUsernameFromToken(token);
        return (username.equals(userDetails.getUsername()) && !isTokenExpired(token));
    }

    private Boolean isTokenExpired(String token) {
        final Date expiration = getExpirationDateFromToken(token);
        return expiration.before(new Date());
    }
}

4. 用户实体类

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@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    private String username;
    private String password;
    private String email;
    
    @ElementCollection(fetch = FetchType.EAGER)
    @CollectionTable(name = "user_roles", 
        joinColumns = @JoinColumn(name = "user_id"))
    @Column(name = "role")
    private Set<String> roles;
    
    // getters and setters
}

5. 用户详情服务

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@Service
public class UserDetailsServiceImpl implements UserDetailsService {

    @Autowired
    private UserRepository userRepository;

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        User user = userRepository.findByUsername(username)
            .orElseThrow(() -> new UsernameNotFoundException("User not found"));
        
        return new org.springframework.security.core.userdetails.User(
            user.getUsername(), 
            user.getPassword(),
            getAuthorities(user.getRoles())
        );
    }

    private Collection<? extends GrantedAuthority> getAuthorities(Set<String> roles) {
        return roles.stream()
            .map(role -> new SimpleGrantedAuthority(role))
            .collect(Collectors.toList());
    }
}

6. 认证过滤器

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@Component
public class JwtAuthenticationFilter extends OncePerRequestFilter {

    @Autowired
    private JwtTokenUtil jwtTokenUtil;

    @Autowired
    private UserDetailsService userDetailsService;

    @Override
    protected void doFilterInternal(HttpServletRequest request, 
                                   HttpServletResponse response, 
                                   FilterChain chain)
                                   throws ServletException, IOException {
        
        final String requestTokenHeader = request.getHeader("Authorization");
        
        String username = null;
        String jwtToken = null;
        
        if (requestTokenHeader != null && requestTokenHeader.startsWith("Bearer ")) {
            jwtToken = requestTokenHeader.substring(7);
            try {
                username = jwtTokenUtil.getUsernameFromToken(jwtToken);
            } catch (IllegalArgumentException e) {
                System.out.println("Unable to get JWT Token");
            } catch (ExpiredJwtException e) {
                System.out.println("JWT Token has expired");
            }
        } else {
            logger.warn("JWT Token does not begin with Bearer String");
        }

        if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
            UserDetails userDetails = this.userDetailsService.loadUserByUsername(username);
            
            if (jwtTokenUtil.validateToken(jwtToken, userDetails)) {
                UsernamePasswordAuthenticationToken usernamePasswordAuthenticationToken = 
                    new UsernamePasswordAuthenticationToken(
                        userDetails, 
                        null,
                        userDetails.getAuthorities()
                    );
                usernamePasswordAuthenticationToken
                    .setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                SecurityContextHolder.getContext().setAuthentication(usernamePasswordAuthenticationToken);
            }
        }
        chain.doFilter(request, response);
    }
}

7. 登录控制器

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@RestController
@RequestMapping("/auth")
public class AuthenticationController {

    @Autowired
    private AuthenticationManager authenticationManager;

    @Autowired
    private JwtTokenUtil jwtTokenUtil;

    @Autowired
    private UserDetailsService userDetailsService;

    @PostMapping("/login")
    public ResponseEntity<?> createAuthenticationToken(@RequestBody LoginRequest loginRequest) {
        try {
            authenticationManager.authenticate(
                new UsernamePasswordAuthenticationToken(
                    loginRequest.getUsername(),
                    loginRequest.getPassword()
                )
            );
        } catch (BadCredentialsException e) {
            return ResponseEntity
                .badRequest()
                .body(new ApiResponse(false, "Invalid username or password"));
        }

        final UserDetails userDetails = userDetailsService
            .loadUserByUsername(loginRequest.getUsername());

        final String token = jwtTokenUtil.generateToken(userDetails);

        return ResponseEntity.ok(new JwtResponse(token));
    }

    @PostMapping("/register")
    public ResponseEntity<?> registerUser(@Valid @RequestBody RegisterRequest registerRequest) {
        if(userRepository.existsByUsername(registerRequest.getUsername())) {
            return ResponseEntity
                .badRequest()
                .body(new ApiResponse(false, "Username is already taken"));
        }

        if(userRepository.existsByEmail(registerRequest.getEmail())) {
            return ResponseEntity
                .badRequest()
                .body(new ApiResponse(false, "Email is already in use"));
        }

        User user = new User();
        user.setUsername(registerRequest.getUsername());
        user.setEmail(registerRequest.getEmail());
        user.setPassword(passwordEncoder.encode(registerRequest.getPassword()));
        user.setRoles(new HashSet<>(Arrays.asList("ROLE_USER")));

        userRepository.save(user);

        return ResponseEntity.ok(new ApiResponse(true, "User registered successfully"));
    }
}

8. 安全配置类

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@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private JwtAuthenticationEntryPoint jwtAuthenticationEntryPoint;

    @Autowired
    private UserDetailsService userDetailsService;

    @Autowired
    private JwtRequestFilter jwtRequestFilter;

    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(userDetailsService).passwordEncoder(passwordEncoder());
    }

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

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

    @Override
    protected void configure(HttpSecurity httpSecurity) throws Exception {
        httpSecurity
            .csrf().disable()
            .authorizeRequests()
            .antMatchers("/auth/**").permitAll()
            .anyRequest().authenticated()
            .and()
            .exceptionHandling()
            .authenticationEntryPoint(jwtAuthenticationEntryPoint)
            .and()
            .sessionManagement()
            .sessionCreationPolicy(SessionCreationPolicy.STATELESS);

        httpSecurity.addFilterBefore(jwtRequestFilter, UsernamePasswordAuthenticationFilter.class);
    }
}

9. 异常处理

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@RestControllerAdvice
public class ExceptionHandler {

    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<?> handleValidationExceptions(
      MethodArgumentNotValidException ex) {
        Map<String, String> errors = new HashMap<>();
        ex.getBindingResult().getAllErrors().forEach((error) -> {
            String fieldName = ((FieldError) error).getField();
            String errorMessage = error.getDefaultMessage();
            errors.put(fieldName, errorMessage);
        });
        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
    }

    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<?> resourceNotFoundException(ResourceNotFoundException ex) {
        return new ResponseEntity<>(ex.getMessage(), HttpStatus.NOT_FOUND);
    }

    @ExceptionHandler(Exception.class)
    public ResponseEntity<?> globalExceptionHandler(Exception ex) {
        return new ResponseEntity<>(ex.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

使用示例

  1. 用户注册：
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POST /auth/register
{
    "username": "testuser",
    "email": "test@example.com",
    "password": "password123"
}
  1. 用户登录：
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POST /auth/login
{
    "username": "testuser",
    "password": "password123"
}
  1. 访问受保护的资源：
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GET /api/protected
Authorization: Bearer eyJhbGciOiJIUzUxMiJ9...

注意事项

  1. JWT密钥需要妥善保管，建议使用环境变量配置
  2. 密码需要使用BCrypt加密存储
  3. 添加适当的请求频率限制
  4. 处理token过期和刷新逻辑
  5. 添加适当的错误处理和日志记录
  6. 考虑使用Redis等存储已注销的token
  7. 建议使用HTTPS保护token传输