您可以改进该程序，增强其功能，并学习更多使用并发集合技术的知识。
You can do a lot with the program to enhance its functionality and learn more about working with concurrent collection techniques.
我请您使用本文的zip文件，它包含一个程序来帮助您学习如何使用fop生成pdf文件。
I invite you to make use of the article's zip file, which includes a program that will help you learn how to generate a PDF file using Fop.
实际上，这个程序是人们学习Rails时使用到的一个演示应用程序。
In fact, it's one of the demo applications that people use when learning Rails.
应用推荐