一个可以跟踪系统执行顺序的类，把他应用到程序中可以记录执行这句话执行的时间，从而跟踪程序执行顺序，尤其适用于多线程跟踪-An execution order of the class tracking system, he applied to the program execution time can be recorded in the execution of this sentence to track the program sequence, in particular for m