今天在学习ssh框架的时候，遇到了这样一个问题：
The file cannot be validated as the XML deFinition "http://www.opensymphony.com/xwork/xwork-
validator-1.0.2.dtd" that is specified as describing the Syntax of the file cannot be located.
出问题的代码：
<!DOCTYPE validators PUBLIC "-//OpenSymphony Group//XWork Validator 1.0.2//EN"
"http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">
The file cannot be validated as the XML deFinition "http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd" that is specified as describing the Syntax of the file cannot be located.
出问题的原因貌似是http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd这个网址访问不了
解决办法：
将<!DOCTYPE>这一项改为：
<!DOCTYPE validators PUBLIC "-//Apache Struts//XWork Validator 1.0.2//EN" "http://struts.apache.org/dtds/xwork-validator-1.0.2.dtd">
