从键盘输入一首诗，把它写入到文本文件poem.txt中。以便初学者掌握熟悉java运行环境，编程掌握Java输入输出流和Swing组件的用法-A poem from the keyboard, put it in writing to a text file poem.txt. For beginners to master familiar with the java runtime environment, to master the Java programming input and o