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package org.apache.taglibs.standard.tag.common.xml;
import javax.xml.xpath.XPathVariableResolver;
import javax.xml.namespace.QName;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.PageContext;
/**
* The XPathVariableResolver implementation provides access to user
* XPath variables.
*/
public class JSTLXPathVariableResolver implements XPathVariableResolver {
//*********************************************************************
// Support for XPath evaluation
private PageContext pageContext;
// The URLs
private static final String PAGE_NS_URL =
"http://java.sun.com/jstl/xpath/page";
private static final String REQUEST_NS_URL =
"http://java.sun.com/jstl/xpath/request";
private static final String SESSION_NS_URL =
"http://java.sun.com/jstl/xpath/session";
private static final String APP_NS_URL =
"http://java.sun.com/jstl/xpath/app";
private static final String PARAM_NS_URL =
"http://java.sun.com/jstl/xpath/param";
private static final String INITPARAM_NS_URL =
"http://java.sun.com/jstl/xpath/initParam";
private static final String COOKIE_NS_URL =
"http://java.sun.com/jstl/xpath/cookie";
private static final String HEADER_NS_URL =
"http://java.sun.com/jstl/xpath/header";
//*********************************************************************
// Constructor
public JSTLXPathVariableResolver(PageContext pc) {
pageContext = pc;
}
/**
* Find variable in set of variables
*
* @param QName variable name
*
* @return QName variables value
*
* @throws NullPointerException if variable name is null
*/
public Object resolveVariable(QName qname) throws NullPointerException {
Object varObject = null;
if (qname == null) {
throw new NullPointerException("Cannot resolve null variable");
}
String namespace = qname.getNamespaceURI();
String prefix = qname.getPrefix();
String localName = qname.getLocalPart();
// p("[resolveVariable] namespace: " + namespace + " prefix: " + prefix + " localName: " + localName);
try {
varObject = getVariableValue(namespace, prefix, localName);
} catch (UnresolvableException ue) {
System.out.println("JSTLXpathVariableResolver.resolveVariable threw UnresolvableException: " + ue);
}
// p("[resolveVariable] varObject: " + varObject);
return varObject;
}
/**
* Retrieve an XPath's variable value using JSTL's custom
* variable-mapping rules
*/
protected Object getVariableValue(String namespace,
String prefix,
String localName)
throws UnresolvableException {
// p("resolving: ns=" + namespace + " prefix=" + prefix + " localName=" + localName);
// We can match on namespace with Xalan but leaving as is
// [ I 'd prefer to match on namespace, but this doesn't appear
// to work in Jaxen]
if (namespace == null || namespace.equals("")) {
return notNull(
pageContext.findAttribute(localName),
namespace,
localName);
} else if (namespace.equals(PAGE_NS_URL)) {
return notNull(
pageContext.getAttribute(localName,PageContext.PAGE_SCOPE),
namespace,
localName);
} else if (namespace.equals(REQUEST_NS_URL)) {
return notNull(
pageContext.getAttribute(localName,
PageContext.REQUEST_SCOPE),
namespace,
localName);
} else if (namespace.equals(SESSION_NS_URL)) {
return notNull(
pageContext.getAttribute(localName,
PageContext.SESSION_SCOPE),
namespace,
localName);
} else if (namespace.equals(APP_NS_URL)) {
return notNull(
pageContext.getAttribute(localName,
PageContext.APPLICATION_SCOPE),
namespace,
localName);
} else if (namespace.equals(PARAM_NS_URL)) {
return notNull(
pageContext.getRequest().getParameter(localName),
namespace,
localName);
} else if (namespace.equals(INITPARAM_NS_URL)) {
return notNull(
pageContext.getServletContext().
getInitParameter(localName),
namespace,
localName);
} else if (namespace.equals(HEADER_NS_URL)) {
HttpServletRequest hsr =
(HttpServletRequest) pageContext.getRequest();
return notNull(
hsr.getHeader(localName),
namespace,
localName);
} else if (namespace.equals(COOKIE_NS_URL)) {
HttpServletRequest hsr =
(HttpServletRequest) pageContext.getRequest();
Cookie[] c = hsr.getCookies();
for (int i = 0; i < c.length; i++)
if (c[i].getName().equals(localName))
return c[i].getValue();
throw new UnresolvableException("$" + namespace + ":" + localName);
} else {
throw new UnresolvableException("$" + namespace + ":" + localName);
}
}
/**
* Validate that the Object returned is not null. If it is
* null, throw an exception.
*/
private Object notNull(Object o, String namespace, String localName)
throws UnresolvableException {
if (o == null) {
throw new UnresolvableException("$" + (namespace==null?"":namespace+":") + localName);
}
// p("resolved to: " + o);
return o;
}
//*********************************************************************
// Utility methods
private static void p(String s) {
System.out.println("[JSTLXPathVariableResolver] " + s);
}
}
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