The reason is that HTTP://WWW.OPENSYMPHONY.COM/XWORK/XWORK-VALIDATOR-1.0.2.DTD is no longer a DTD constraint file,
Open the URL, found that Opensymphony's URL has been migrated away, because xwork things have been incorporated into STRUTS2, become part of Apache.
All the DTDs have been handed over to http://struts.apache.org/dtds/this place.
Later, the specification of the Struts2 Checker should be changed to:
<?xml version= "1.0" encoding= "UTF-8"?>
<! DOCTYPE validators Public "-//apache struts//xwork Validator 1.0.2//en" "http://struts.apache.org/dtds/ Xwork-validator-1.0.2.dtd ">
Window---->myeclipse---->files and Editors---->xml---->xml Catalog, click on the "Add" button to pop up the Add XML catalog Element windows , click "File System ..." button, locate the downloaded DTD file (XWORK-VALIDATOR-1.0.2.DTD), click on the "OK" button, and enter after key: ("-//apache struts//xwork validator 1.0.2//en" "/HTTP/ Struts.apache.org/dtds/xwork-validator-1.0.2.dtd ") to automatically apply a DTD when creating an XML file
Add XML Catalog (Xwork-validator DTD) in MyEclipse