说明：  疯狂的打印机. 分别使用 Thread 和 Runnable写具有两个同样功能的线程，打印从1-1000的数字。将靠后start的线程的优先级设为8，再执行一次。两次结果分别输出至“writer.txt”和“writer8.txt”
(Crazy printer respectively use Thread and Runnable write the same function with two threads, printing digital 1-1000. The rearward start the thread priority set to 8, then again. Two results are output to the " writer.txt" and " writer8.txt" )