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Spring Security入门：构建安全应用

在Java开发领域，Spring Security是实现应用安全的首选框架。深入了解这个强大的安全框架，掌握认证与授权的核心技术。

一、什么是Spring Security？

Spring Security是Spring生态系统中最强大的安全框架，它为Java应用提供全面的安全服务。无论是传统Web应用，还是RESTful API，甚至是微服务架构，Spring Security都能提供可靠的安全保障。

为什么选择Spring Security？

• 功能全面：涵盖认证、授权、防护等所有安全需求
• 高度可定制：灵活扩展，满足各种业务场景
• 社区活跃：Spring官方维护，文档完善
• 与Spring深度集成：无缝衔接Spring Boot

二、核心概念

2.1 认证 vs 授权

• 认证：确认"你是谁"，如登录验证
• 授权：确认"你能做什么"，如权限控制

2.2 核心组件

三、项目搭建

3.1 添加依赖

<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>3.2.0</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies>

3.2 基础配置类

@Configuration @EnableWebSecurity public class SecurityConfig { @Bean public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception { http .authorizeHttpRequests(auth -> auth .requestMatchers("/public/**").permitAll() .anyRequest().authenticated() ) .formLogin(form -> form .loginPage("/login") .defaultSuccessUrl("/home") ); return http.build(); } @Bean public PasswordEncoder passwordEncoder() { return new BCryptPasswordEncoder(); } }

四、认证流程详解

Spring Security的认证流程是一个精心设计的链式处理过程：

1. 用户提交认证信息：用户名和密码
2. 创建Authentication对象：封装认证信息
3. AuthenticationManager验证：委托给Provider
4. 加载用户详情：通过UserDetailsService
5. 验证成功：存入SecurityContext

4.1 自定义用户详情服务

@Service public class CustomUserDetailsService implements UserDetailsService { @Autowired private UserRepository userRepository; @Override public UserDetails loadUserByUsername(String username) { User user = userRepository.findByUsername(username) .orElseThrow(() -> new UsernameNotFoundException("用户不存在")); return User.builder() .username(user.getUsername()) .password(user.getPassword()) .roles(user.getRoles().toArray(new String[0])) .build(); } }

4.2 自置认证提供者

@Component public class CustomAuthenticationProvider implements AuthenticationProvider { @Autowired private UserDetailsService userDetailsService; @Autowired private PasswordEncoder passwordEncoder; @Override public Authentication authenticate(Authentication authentication) { String username = authentication.getName(); String password = authentication.getCredentials().toString(); UserDetails userDetails = userDetailsService.loadUserByUsername(username); if (passwordEncoder.matches(password, userDetails.getPassword())) { return new UsernamePasswordAuthenticationToken( username, password, userDetails.getAuthorities() ); } throw new BadCredentialsException("密码错误"); } @Override public boolean supports(Class<?> authentication) { return authentication.equals(UsernamePasswordAuthenticationToken.class); } }

五、授权机制

授权是指确定用户是否有权访问特定资源的过程。Spring Security支持多种授权方式。

5.1 URL级别授权

@Bean public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception { http .authorizeHttpRequests(auth -> auth // 公开接口 .requestMatchers("/api/public/**").permitAll() // 管理员专属 .requestMatchers("/api/admin/**").hasRole("ADMIN") // 需要特定权限 .requestMatchers("/api/write/**").hasAuthority("WRITE") // 已认证用户 .anyRequest().authenticated() ); return http.build(); }

5.2 方法级授权

@RestController @RequestMapping("/api") public class ApiController { // 需要USER角色 @GetMapping("/user") @PreAuthorize("hasRole('USER')") public String userEndpoint() { return "用户专属内容"; } // 需要ADMIN角色 @GetMapping("/admin") @PreAuthorize("hasRole('ADMIN')") public String adminEndpoint() { return "管理员专属内容"; } // 复杂表达式 @GetMapping("/secure") @PreAuthorize("hasRole('ADMIN') and #username == authentication.name") public String secureEndpoint(String username) { return "只能访问自己的数据"; } // 返回后过滤 @GetMapping("/data/{id}") @PostAuthorize("returnObject.owner == authentication.name") public Data getData(@PathVariable Long id) { return dataService.findById(id); } }

5.3 自定义权限注解

@Target(ElementType.METHOD) @Retention(RetentionPolicy.RUNTIME) @PreAuthorize("hasRole('ADMIN') or hasRole('SUPERVISOR')") public @interface IsAdminOrSupervisor { }

六、JWT令牌认证

JWT（JSON Web Token）是目前最流行的跨域认证解决方案。

6.1 JWT服务类

@Service public class JwtService { @Value("${jwt.secret}") private String secret; @Value("${jwt.expiration}") private Long expiration; public String generateToken(String username, List<String> roles) { Map<String, Object> claims = new HashMap<>(); claims.put("roles", roles); return Jwts.builder() .claims(claims) .subject(username) .issuedAt(new Date()) .expiration(new Date(System.currentTimeMillis() + expiration)) .signWith(getSigningKey()) .compact(); } public String extractUsername(String token) { return extractClaims(token).getSubject(); } public boolean validateToken(String token, String username) { String extractedUsername = extractUsername(token); return extractedUsername.equals(username) && !isTokenExpired(token); } private Claims extractClaims(String token) { return Jwts.parser() .verifyWith(getSigningKey()) .build() .parseSignedClaims(token) .getPayload(); } }

6.2 JWT认证过滤器

@Component public class JwtAuthenticationFilter extends OncePerRequestFilter { @Autowired private JwtService jwtService; @Override protected void doFilterInternal( HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { String token = extractTokenFromRequest(request); if (token != null && SecurityContextHolder.getContext().getAuthentication() == null) { String username = jwtService.extractUsername(token); if (username != null) { List<String> roles = jwtService.extractRoles(token); UsernamePasswordAuthenticationToken authToken = new UsernamePasswordAuthenticationToken( username, null, roles.stream() .map(role -> new SimpleGrantedAuthority("ROLE_" + role)) .collect(Collectors.toList()) ); SecurityContextHolder.getContext().setAuthentication(authToken); } } filterChain.doFilter(request, response); } private String extractTokenFromRequest(HttpServletRequest request) { String bearerToken = request.getHeader("Authorization"); if (bearerToken != null && bearerToken.startsWith("Bearer ")) { return bearerToken.substring(7); } return null; } }

6.3 登录控制器

@RestController @RequestMapping("/api/auth") public class AuthController { @Autowired private AuthenticationManager authenticationManager; @Autowired private JwtService jwtService; @PostMapping("/login") public LoginResponse login(@RequestBody LoginRequest request) { Authentication authentication = authenticationManager.authenticate( new UsernamePasswordAuthenticationToken( request.getUsername(), request.getPassword() ) ); User user = (User) authentication.getPrincipal(); String token = jwtService.generateToken( user.getUsername(), user.getAuthorities().stream() .map(GrantedAuthority::getAuthority) .collect(Collectors.toList()) ); return new LoginResponse(token, user.getUsername()); } }

七、过滤器链机制

Spring Security通过过滤器链处理所有HTTP请求，理解过滤器链的工作原理对定制安全功能至关重要。

7.1 常用过滤器

7.2 自定义过滤器

public class CustomFilter extends OncePerRequestFilter { @Override protected void doFilterInternal( HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { // 前置处理 String requestId = UUID.randomUUID().toString(); request.setAttribute("requestId", requestId); // 继续过滤器链 filterChain.doFilter(request, response); // 后置处理 logger.info("Request {} completed", requestId); } } // 注册自定义过滤器 @Bean public SecurityFilterChain securityFilterChain(HttpSecurity http) { http.addFilterBefore(new CustomFilter(), UsernamePasswordAuthenticationFilter.class); return http.build(); }

八、异常处理

@Component public class CustomAuthenticationEntryPoint implements AuthenticationEntryPoint { @Override public void commence( HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException { response.setStatus(HttpServletResponse.SC_UNAUTHORIZED); response.setContentType("application/json;charset=UTF-8"); ApiResponse<?> apiResponse = ApiResponse.unauthorized("未登录或登录已过期"); response.getWriter().write(new ObjectMapper().writeValueAsString(apiResponse)); } } @Component public class CustomAccessDeniedHandler implements AccessDeniedHandler { @Override public void handle( HttpServletRequest request, HttpServletResponse response, AccessDeniedException accessDeniedException) throws IOException { response.setStatus(HttpServletResponse.SC_FORBIDDEN); response.setContentType("application/json;charset=UTF-8"); ApiResponse<?> apiResponse = ApiResponse.error("权限不足"); response.getWriter().write(new ObjectMapper().writeValueAsString(apiResponse)); } }

九、应用场景

9.1 企业后台系统

典型的RBAC（基于角色的访问控制）场景：

• 用户表、角色表、权限表
• 用户-角色、角色-权限多对多关系
• 支持动态权限配置

9.2 API网关

统一认证授权中心：

• JWT令牌签发与验证
• 单点登录支持
• 第三方登录集成

十、总结

Spring Security是企业级Java应用的安全基石：

• 核心功能：认证与授权
• 扩展能力：过滤器链、自定义提供者
• 现代方案：JWT、OAuth2