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">

错误提示：

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">