通过浏览器的事件机制来捕获用户的键盘事件-Through the browser' s event mechanism to capture user' s keyboard events

Krabber项目是支持Ajax动态内容抓取的网页信息抽取程序。这是Krabber的开发文档。-Krabber project is to support Ajax dynamic content capture Web information extraction process. This is Krabber development documentation.

* 自定义两个exception exception类 *编写一段程序使用这两个类：从标准输入读入字符串， *当字符串为空时抛出一 个exception， *当字符串包含阿拉伯数字 时抛出另一个exception；捕获exception -* Custom two exception exception class* write a program to use these two categories: the string read the standard inp