拦截器里MDC.put后，异常了，怎么保证MDC.clear

在拦截器中，可以使用try-catch-finally块来确保MDC.clear()在任何情况下都会被调用。在try块中设置MDC，然后在finally块中调用MDC.clear()。这样可以确保即使发生异常，MDC也会被清除。以下是示例代码：

public class MyInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        MDC.put("requestId", UUID.randomUUID().toString());
        return true;
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        try {
            // do something
        } catch (Exception e) {
            // handle exception
        } finally {
            MDC.clear();
        }
    }
}