所有validation.xml的声明需要修改为：
<!DOCTYPE validators PUBLIC
"-//Apache Struts//XWork Validator 1.0.2//EN"
"http://struts.apache.org/dtds/xwork-validator-1.0.2.dtd">
否则会出现以下异常：
[ERROR] 2013-07-23 17:06:58(41144) --> [http-8080-3] com.opensymphony.xwork2.util.logging.commons.CommonsLogger.error(CommonsLogger.java:38): Caught exception while loading file cn/test/action/UserLoginAction-login-validation.xml Connection timed out: connect - [unknown location] at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:119) at com.opensymphony.xwork2.validator.DefaultValidatorFileParser.parseActionValidatorConfigs(DefaultValidatorFileParser.java:82) at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.loadFile(AnnotationActionValidatorManager.java:394) at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.buildAliasValidatorConfigs(AnnotationActionValidatorManager.java:271) at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.buildValidatorConfigs(AnnotationActionValidatorManager.java:374) at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.getValidators(AnnotationActionValidatorManager.java:102) at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.validate(AnnotationActionValidatorManager.java:141) at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.validate(AnnotationActionValidatorManager.java:133) at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.validate(AnnotationActionValidatorManager.java:128) at com.opensymphony.xwork2.validator.ValidationInterceptor.doBeforeInvocation(ValidationInterceptor.java:222) at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263) at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
