{ "alg": "HS256", "typ": "JWT" }

{ "sub": "1234567890", "name": "John Doe", "admin": true }

HMACSHA256( base64UrlEncode(header) + "." + base64UrlEncode(payload), secret)

public class JwtTokenUtils {
  // token私鑰
  private static final String TOKEN_SECRET = "jwtSECRET";
  // token過期時(shí)長(zhǎng)30分鐘
  private static final long EXPIRE_TIME = 1800L; // 單位為秒
  /**
   * 生成用戶token,設(shè)置token超時(shí)時(shí)間
   *
   * @return 生成的token
   */
   public static String createToken(LoginVo loginVo) {
    Date expireDate = new Date(System.currentTimeMillis() + EXPIRE_TIME * 1000);
    // 創(chuàng)建 Token 的 payload
    Map<String, Object> map = new HashMap<>();
    map.put("alg", "HS256");
    map.put("typ", "JWT");
    // 生成 JWT Token
    String token = JWT.create()
      .withHeader(map)// 添加頭部
      .withClaim("account", loginVo.getAccount())
      .withExpiresAt(expireDate) //超時(shí)設(shè)置,設(shè)置過期的日期
      .withIssuedAt(new Date()) //簽發(fā)時(shí)間
      .sign(Algorithm.HMAC256(TOKEN_SECRET)); //SECRET加密
    return token;
  }
  /**
   * 檢驗(yàn)token是否正確
   * @param token 需要校驗(yàn)的token
   * @return 校驗(yàn)是否成功
   */
  public static Map<String, Claim> verifyToken(String token) {
    DecodedJWT jwt = null;
    token = token.replace("Bearer ", ""); // 這里要去掉Bearer ，postman默認(rèn)會(huì)加這個(gè)，導(dǎo)致匹配不上
    try {
      //設(shè)置簽名的加密算法：HMAC256
      Algorithm algorithm = Algorithm.HMAC256(TOKEN_SECRET); // 私鑰需要一致
      JWTVerifier verifier = JWT.require(algorithm).build();
      jwt = verifier.verify(token);
    } catch (Exception e) {
//      logger.error(e.getMessage()); // 還沒安裝log4j等日志依賴，先注釋
//      logger.error("token解碼異常");
      //解碼異常則拋出異常
      return null;
    }
    return jwt.getClaims();
  }
}

@Component
@WebFilter(filterName = "JwtFilter", urlPatterns = "/*")
public class JwtFilter implements Filter {
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
    System.out.println("jwt初始化方法");
  }
  @Override
  public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
    final HttpServletRequest request = (HttpServletRequest) req;
    final HttpServletResponse response = (HttpServletResponse) res;
    response.setCharacterEncoding("UTF-8");
    final String token = request.getHeader("Authorization");
    String requestPath = request.getRequestURI();
    // 登錄接口，直接放行
    if (requestPath.contains("/user/login")) {
      chain.doFilter(request, response);
      return;
    }
     if ("OPTIONS".equals(request.getMethod())) { // 是否是 OPTIONS 請(qǐng)求
      response.setStatus(HttpServletResponse.SC_OK);
      chain.doFilter(request, response);
    } else {
      if (token == null) {
        response.getWriter().write("沒有令牌");
        return;
      }
      Map<String, Claim> userData = JwtTokenUtils.verifyToken(token); // 檢驗(yàn) token
      if (userData == null) {
        response.getWriter().write("令牌非法");
        return;
      }
      String account = userData.get("account").asString(); // 獲取用戶名
      request.setAttribute("account", account); // 設(shè)置用戶名
      chain.doFilter(req, res); // 過濾成功
    }
  }
  @Override
  public void destroy() {
    System.out.println("jwt銷毀方法執(zhí)行的邏輯");
  }
}

@Controller
@RestController  // 可處理 HTTP 請(qǐng)求的控制器，并且能夠返回?cái)?shù)據(jù)給客戶端
@RequestMapping("/user")
@RequiredArgsConstructor
public class LoginController {
  private final AdminService adminService;
  // 用戶登陸
  @GetMapping("/login")
  ResultVO<Object> login(LoginVo loginVo) {
    Admin admin = new Admin();
    admin.setAccount(loginVo.getAccount());
    admin.setAdminPassword(loginVo.getAdminPassword());
    // 查找是否有該管理員
    Admin an = adminService.queryByAdmin(admin);
    if (an == null) {
      return ResultResponse.failure(ResultCodeEnum.INTERNAL_NOT_FOUND);
    } else {
      String token = JwtTokenUtils.createToken(loginVo);
      loginVo.setToken(token);
      an.setToken(token);
      return ResultResponse.success(an);
    }
  }
  @GetMapping("/secure/current_registrant")
  public String currentRegistrant(HttpServletRequest request) {
    System.out.println("request" + request);
    String id = request.getParameter("id");
    String account = request.getParameter("account");
    String user_password = request.getParameter("adminPassword");
    return "當(dāng)前用戶信息: id=" + id + " ,account=" + account + " ,user_password=" + user_password;
  }
}