浅谈SpringMVC HandlerInterceptor诡异问题排查

/** * 用户登录下上文 * * @author : jamesfu * @date : 22/5/2019 * @time : 9:18 AM */@Datapublic class UserContext {  private final static ThreadLocal<UserContext> threadLocal = new ThreadLocal<>();  private Long id;  private String loginName;  public static UserContext get() {    UserContext context = threadLocal.get();    if (context == null) {      // TODO(james.h.fu):根据请求上下文获取token, 然后恢复用户登录下上文      context = new UserContext() {{        setId(1L);        setLoginName("james.h.fu1");      }};      threadLocal.set(context);    }    return context;  }  public static void clear() {    threadLocal.remove();  }  public static void set(UserContext context) {    if (context != null) {      threadLocal.set(context);    }  }}

/** * 拦截器注册配置 * * @author : jamesfu * @date : 22/5/2019 * @time : 9:15 AM */@Configurationpublic class FilterConfig implements WebMvcConfigurer {  @Autowired  private JsonRpcInterceptor jsonRpcInterceptor;  @Override  public void addInterceptors(InterceptorRegistry registry) {    registry.addInterceptor(jsonRpcInterceptor)        .addPathPatterns("/json.rpc");  }}

/**	 * Process the actual dispatching to the handler.	 * <p>The handler will be obtained by applying the servlet's HandlerMappings in order.	 * The HandlerAdapter will be obtained by querying the servlet's installed HandlerAdapters	 * to find the first that supports the handler class.	 * <p>All HTTP methods are handled by this method. It's up to HandlerAdapters or handlers	 * themselves to decide which methods are acceptable.	 * @param request current HTTP request	 * @param response current HTTP response	 * @throws Exception in case of any kind of processing failure	 */	protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception

/**	 * Apply preHandle methods of registered interceptors.	 * @return {@code true} if the execution chain should proceed with the	 * next interceptor or the handler itself. Else, DispatcherServlet assumes	 * that this interceptor has already dealt with the response itself.	 */	boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {		HandlerInterceptor[] interceptors = getInterceptors();		if (!ObjectUtils.isEmpty(interceptors)) {			for (int i = 0; i < interceptors.length; i++) {				HandlerInterceptor interceptor = interceptors[i];				if (!interceptor.preHandle(request, response, this.handler)) {					triggerAfterCompletion(request, response, null);					return false;				}				this.interceptorIndex = i;			}		}		return true;	}

/**	 * Trigger afterCompletion callbacks on the mapped HandlerInterceptors.	 * Will just invoke afterCompletion for all interceptors whose preHandle invocation	 * has successfully completed and returned true.	 */	void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, @Nullable Exception ex)			throws Exception {		HandlerInterceptor[] interceptors = getInterceptors();		if (!ObjectUtils.isEmpty(interceptors)) {			for (int i = this.interceptorIndex; i >= 0; i--) {				HandlerInterceptor interceptor = interceptors[i];				try {					interceptor.afterCompletion(request, response, this.handler, ex);				}				catch (Throwable ex2) {					logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);				}			}		}	}