package freemarker.ext.jsp;
import java.security.AccessController;
import java.security.PrivilegedAction;
import javax.el.ELContext;
import javax.servlet.jsp.JspApplicationContext;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.JspFactory;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.el.ELException;
import javax.servlet.jsp.el.ExpressionEvaluator;
import javax.servlet.jsp.el.VariableResolver;
import freemarker.log.Logger;
import freemarker.template.TemplateModelException;
/**
* Implementation of PageContext that contains JSP 2.0 and JSP 2.1 specific methods.
*
* @author Attila Szegedi
* @version $Id: FreeMarkerPageContext2.java,v 1.1 2005/06/11 12:13:39 szegedia Exp $
*/
class FreeMarkerPageContext21 extends FreeMarkerPageContext {
private static final Logger logger = Logger.getLogger("freemarker.jsp");
static {
if(JspFactory.getDefaultFactory() == null) {
JspFactory.setDefaultFactory(new FreeMarkerJspFactory21());
}
logger.debug("Using JspFactory implementation class " +
JspFactory.getDefaultFactory().getClass().getName());
}
private FreeMarkerPageContext21() throws TemplateModelException {
super();
}
static FreeMarkerPageContext create() throws TemplateModelException {
return new FreeMarkerPageContext21();
}
/**
* Attempts to locate and manufacture an expression evaulator instance. For this
* to work you <b>must</b> have the Apache Commons-EL package in the classpath. If
* Commons-EL is not available, this method will throw an UnsupportedOperationException.
*/
public ExpressionEvaluator getExpressionEvaluator() {
try {
Class type = ((ClassLoader)AccessController.doPrivileged(
new PrivilegedAction() {
public Object run() {
return Thread.currentThread().getContextClassLoader();
}
})).loadClass
("org.apache.commons.el.ExpressionEvaluatorImpl");
return (ExpressionEvaluator) type.newInstance();
}
catch (Exception e) {
throw new UnsupportedOperationException("In order for the getExpressionEvaluator() " +
"method to work, you must have downloaded the apache commons-el jar and " +
"made it available in the classpath.");
}
}
/**
* Returns a variable resolver that will resolve variables by searching through
* the page scope, request scope, session scope and application scope for an
* attribute with a matching name.
*/
public VariableResolver getVariableResolver() {
final PageContext ctx = this;
return new VariableResolver() {
public Object resolveVariable(String name) throws ELException {
return ctx.findAttribute(name);
}
};
}
private ELContext elContext;
public ELContext getELContext() {
if(elContext == null) {
JspApplicationContext jspctx = JspFactory.getDefaultFactory().getJspApplicationContext(getServletContext());
if(jspctx instanceof FreeMarkerJspApplicationContext) {
elContext = ((FreeMarkerJspApplicationContext)jspctx).createNewELContext(this);
elContext.putContext(JspContext.class, this);
}
else {
throw new UnsupportedOperationException(
"Can not create an ELContext using a foreign JspApplicationContext\n" +
"Consider dropping a private instance of JSP 2.1 API JAR file in\n" +
"your WEB-INF/lib directory and then try again.");
}
}
return elContext;
}
}
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