1 简介
Spring Security作为成熟且强大的安全框架,得到许多大厂的青睐。而作为前后端分离的SSO方案,JWT也在许多项目中应用。本文将介绍如何通过Spring Security实现JWT认证。
用户与服务器交互大概如下:

- 客户端获取JWT,一般通过POST方法把用户名/密码传给server;
- 服务端接收到客户端的请求后,会检验用户名/密码是否正确,如果正确则生成JWT并返回;不正确则返回错误;
- 客户端拿到JWT后,在有效期内都可以通过JWT来访问资源了,一般把JWT放在请求头;一次获取,多次使用;
- 服务端校验JWT是否合法,合法则允许客户端正常访问,不合法则返回401。
 
2 项目整合
我们把要整合的Spring Security和JWT加入到项目的依赖中去:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>io.jsonwebtoken</groupId> <artifactId>jjwt</artifactId> <version>0.9.1</version> </dependency>
2.1 JWT整合
2.1.1 JWT工具类
JWT工具类起码要具有以下功能:
- 根据用户信息生成JWT;
- 校验JWT是否合法,如是否被篡改、是否过期等;
- 从JWT中解析用户信息,如用户名、权限等;
具体代码如下:
@Component
public class JwtTokenProvider {
 @Autowired JwtProperties jwtProperties;
 @Autowired
 private CustomUserDetailsService userDetailsService;
 private String secretKey;
 @PostConstruct
 protected void init() {
  secretKey = Base64.getEncoder().encodeToString(jwtProperties.getSecretKey().getBytes());
 }
 public String createToken(String username, List<String> roles) {
  Claims claims = Jwts.claims().setSubject(username);
  claims.put("roles", roles);
  Date now = new Date();
  Date validity = new Date(now.getTime() + jwtProperties.getValidityInMs());
  return Jwts.builder()//
    .setClaims(claims)//
    .setIssuedAt(now)//
    .setExpiration(validity)//
    .signWith(SignatureAlgorithm.HS256, secretKey)//
    .compact();
 }
 public Authentication getAuthentication(String token) {
  UserDetails userDetails = this.userDetailsService.loadUserByUsername(getUsername(token));
  return new UsernamePasswordAuthenticationToken(userDetails, "", userDetails.getAuthorities());
 }
 public String getUsername(String token) {
  return Jwts.parser().setSigningKey(secretKey).parseClaimsJws(token).getBody().getSubject();
 }
 public String resolveToken(HttpServletRequest req) {
  String bearerToken = req.getHeader("Authorization");
  if (bearerToken != null && bearerToken.startsWith("Bearer ")) {
   return bearerToken.substring(7);
  }
  return null;
 }
 public boolean validateToken(String token) {
  try {
   Jws<Claims> claims = Jwts.parser().setSigningKey(secretKey).parseClaimsJws(token);
   if (claims.getBody().getExpiration().before(new Date())) {
    return false;
   }
   return true;
  } catch (JwtException | IllegalArgumentException e) {
   throw new InvalidJwtAuthenticationException("Expired or invalid JWT token");
  }
 }
}
工具类还实现了另一个功能:从HTTP请求头中获取JWT。
2.1.2 Token处理的Filter
Filter是Security处理的关键,基本上都是通过Filter来拦截请求的。首先从请求头取出JWT,然后校验JWT是否合法,如果合法则取出Authentication保存在SecurityContextHolder里。如果不合法,则做异常处理。
public class JwtTokenAuthenticationFilter extends GenericFilterBean {
 private JwtTokenProvider jwtTokenProvider;
 public JwtTokenAuthenticationFilter(JwtTokenProvider jwtTokenProvider) {
  this.jwtTokenProvider = jwtTokenProvider;
 }
 @Override
 public void doFilter(ServletRequest req, ServletResponse res, FilterChain filterChain)
   throws IOException, ServletException {
  HttpServletRequest request = (HttpServletRequest) req;
  HttpServletResponse response = (HttpServletResponse) res;
  try {
   String token = jwtTokenProvider.resolveToken(request);
   if (token != null && jwtTokenProvider.validateToken(token)) {
    Authentication auth = jwtTokenProvider.getAuthentication(token);
    if (auth != null) {
     SecurityContextHolder.getContext().setAuthentication(auth);
    }
   }
  } catch (InvalidJwtAuthenticationException e) {
   response.setStatus(HttpStatus.UNAUTHORIZED.value());
   response.getWriter().write("Invalid token");
   response.getWriter().flush();
   return;
  }
  filterChain.doFilter(req, res);
 }
}
对于异常处理,使用@ControllerAdvice是不行的,应该这个是Filter,在这里抛的异常还没有到DispatcherServlet,无法处理。所以Filter要自己做异常处理:
catch (InvalidJwtAuthenticationException e) {
 response.setStatus(HttpStatus.UNAUTHORIZED.value());
 response.getWriter().write("Invalid token");
 response.getWriter().flush();
 return;
}
最后的return不能省略,因为已经要把输出的内容给Response了,没有必要再往后传递,否则报错
java.lang.IllegalStateException: getWriter() has already been called
2.1.3 JWT属性
JWT需要配置一个密钥来加密,同时还要配置JWT令牌的有效期。
@Configuration
@ConfigurationProperties(prefix = "pkslow.jwt")
public class JwtProperties {
 private String secretKey = "pkslow.key";
 private long validityInMs = 3600_000;
//getter and setter
}
2.2 Spring Security整合
Spring Security的整个框架还是比较复杂的,简化后大概如下图所示:

它是通过一连串的Filter来进行安全管理。细节这里先不展开讲。
2.2.1 WebSecurityConfigurerAdapter配置
这个配置也可以理解为是FilterChain的配置,可以不用理解,代码很好懂它做了什么:
@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {
 @Autowired
 JwtTokenProvider jwtTokenProvider;
 @Bean
 @Override
 public AuthenticationManager authenticationManagerBean() throws Exception {
  return super.authenticationManagerBean();
 }
 @Bean
 public PasswordEncoder passwordEncoder() {
  return NoOpPasswordEncoder.getInstance();
 }
 @Override
 protected void configure(HttpSecurity http) throws Exception {
  http
   .httpBasic().disable()
   .csrf().disable()
   .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS)
   .and()
   .authorizeRequests()
   .antMatchers("/auth/login").permitAll()
   .antMatchers(HttpMethod.GET, "/admin").hasRole("ADMIN")
   .antMatchers(HttpMethod.GET, "/user").hasRole("USER")
   .anyRequest().authenticated()
   .and()
   .apply(new JwtSecurityConfigurer(jwtTokenProvider));
 }
}
这里通过HttpSecurity配置了哪些请求需要什么权限才可以访问。
- /auth/login用于登陆获取JWT,所以都能访问;
- /admin只有ADMIN用户才可以访问;
- /user只有USER用户才可以访问。
 
而之前实现的Filter则在下面配置使用:
public class JwtSecurityConfigurer extends SecurityConfigurerAdapter<DefaultSecurityFilterChain, HttpSecurity> {
 private JwtTokenProvider jwtTokenProvider;
 public JwtSecurityConfigurer(JwtTokenProvider jwtTokenProvider) {
  this.jwtTokenProvider = jwtTokenProvider;
 }
 @Override
 public void configure(HttpSecurity http) throws Exception {
  JwtTokenAuthenticationFilter customFilter = new JwtTokenAuthenticationFilter(jwtTokenProvider);
  http.exceptionHandling()
    .authenticationEntryPoint(new JwtAuthenticationEntryPoint())
    .and()
    .addFilterBefore(customFilter, UsernamePasswordAuthenticationFilter.class);
 }
}
2.2.2 用户从哪来
通常在Spring Security的世界里,都是通过实现UserDetailsService来获取UserDetails的。
@Component
public class CustomUserDetailsService implements UserDetailsService {
 private UserRepository users;
 public CustomUserDetailsService(UserRepository users) {
  this.users = users;
 }
 @Override
 public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
  return this.users.findByUsername(username)
    .orElseThrow(() -> new UsernameNotFoundException("Username: " + username + " not found"));
 }
}
对于UserRepository,可以从数据库中读取,或者其它用户管理中心。为了方便,我使用Map放了两个用户:
@Repository
public class UserRepository {
 private static final Map<String, User> allUsers = new HashMap<>();
 @Autowired
 private PasswordEncoder passwordEncoder;
 @PostConstruct
 protected void init() {
  allUsers.put("pkslow", new User("pkslow", passwordEncoder.encode("123456"), Collections.singletonList("ROLE_ADMIN")));
  allUsers.put("user", new User("user", passwordEncoder.encode("123456"), Collections.singletonList("ROLE_USER")));
 }
 public Optional<User> findByUsername(String username) {
  return Optional.ofNullable(allUsers.get(username));
 }
}
3 测试
完成代码编写后,我们来测试一下:
(1)无JWT访问,失败
curl http://localhost:8080/admin
{"timestamp":"2021-02-06T05:45:06.385+0000","status":403,"error":"Forbidden","message":"Access Denied","path":"/admin"}
$ curl http://localhost:8080/user
{"timestamp":"2021-02-06T05:45:16.438+0000","status":403,"error":"Forbidden","message":"Access Denied","path":"/user"}
(2)admin获取JWT,密码错误则失败,密码正确则成功
$ curl http://localhost:8080/auth/login -X POST -d '{"username":"pkslow","password":"xxxxxx"}' -H 'Content-Type: application/json'
{"timestamp":"2021-02-06T05:47:16.254+0000","status":403,"error":"Forbidden","message":"Access Denied","path":"/auth/login"}
$ curl http://localhost:8080/auth/login -X POST -d '{"username":"pkslow","password":"123456"}' -H 'Content-Type: application/json'
eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJwa3Nsb3ciLCJyb2xlcyI6WyJST0xFX0FETUlOIl0sImlhdCI6MTYxMjU5MDYxNCwiZXhwIjoxNjEyNTkxMjE0fQ.d4Gi50aaOsHHqpM0d8Mh1960otnZf7rlE3x6xSfakVo 
(3)admin带JWT访问/admin,成功;访问/user失败
$ curl http://localhost:8080/admin -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJwa3Nsb3ciLCJyb2xlcyI6WyJST0xFX0FETUlOIl0sImlhdCI6MTYxMjU5MDYxNCwiZXhwIjoxNjEyNTkxMjE0fQ.d4Gi50aaOsHHqpM0d8Mh1960otnZf7rlE3x6xSfakVo'
you are admin
$ curl http://localhost:8080/user -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJwa3Nsb3ciLCJyb2xlcyI6WyJST0xFX0FETUlOIl0sImlhdCI6MTYxMjU5MDYxNCwiZXhwIjoxNjEyNTkxMjE0fQ.d4Gi50aaOsHHqpM0d8Mh1960otnZf7rlE3x6xSfakVo'
{"timestamp":"2021-02-06T05:51:23.099+0000","status":403,"error":"Forbidden","message":"Forbidden","path":"/user"}
(4)使用过期的JWT访问,失败
$ curl http://localhost:8080/admin -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJwa3Nsb3ciLCJyb2xlcyI6WyJST0xFX0FETUlOIl0sImlhdCI6MTYxMjU5MDQ0OSwiZXhwIjoxNjEyNTkwNTA5fQ.CSaubE4iJcYATbLmbb59aNFU1jNCwDFHUV3zIakPU64' Invalid token
4 总结
代码请查看:https://github.com/LarryDpk/pkslow-samples
以上就是Springboot集成Spring Security实现JWT认证的步骤详解的详细内容,更多关于Springboot集成Spring Security的资料请关注易盾网络其它相关文章!
