package freemarker.ext.jsp;
import java.util.Iterator;
import java.util.LinkedList;
import javax.el.ArrayELResolver;
import javax.el.BeanELResolver;
import javax.el.CompositeELResolver;
import javax.el.ELContext;
import javax.el.ELContextEvent;
import javax.el.ELContextListener;
import javax.el.ELResolver;
import javax.el.ExpressionFactory;
import javax.el.FunctionMapper;
import javax.el.ListELResolver;
import javax.el.MapELResolver;
import javax.el.ResourceBundleELResolver;
import javax.el.ValueExpression;
import javax.el.VariableMapper;
import javax.servlet.jsp.JspApplicationContext;
import javax.servlet.jsp.el.ImplicitObjectELResolver;
import javax.servlet.jsp.el.ScopedAttributeELResolver;
import freemarker.log.Logger;
import freemarker.template.utility.ClassUtil;
/**
* @author Attila Szegedi
* @version $Id: $
*/
class FreeMarkerJspApplicationContext implements JspApplicationContext
{
private static final Logger logger = Logger.getLogger("freemarker.jsp");
private static final ExpressionFactory expressionFactoryImpl = findExpressionFactoryImplementation();
private final LinkedList listeners = new LinkedList();
private final CompositeELResolver elResolver = new CompositeELResolver();
private final CompositeELResolver additionalResolvers = new CompositeELResolver();
{
elResolver.add(new ImplicitObjectELResolver());
elResolver.add(additionalResolvers);
elResolver.add(new MapELResolver());
elResolver.add(new ResourceBundleELResolver());
elResolver.add(new ListELResolver());
elResolver.add(new ArrayELResolver());
elResolver.add(new BeanELResolver());
elResolver.add(new ScopedAttributeELResolver());
}
public void addELContextListener(ELContextListener listener) {
synchronized(listeners) {
listeners.addLast(listener);
}
}
private static ExpressionFactory findExpressionFactoryImplementation() {
ExpressionFactory ef = tryExpressionFactoryImplementation("com.sun");
if(ef == null) {
ef = tryExpressionFactoryImplementation("org.apache");
if(ef == null) {
logger.warn("Could not find any implementation for " +
ExpressionFactory.class.getName());
}
}
return ef;
}
private static ExpressionFactory tryExpressionFactoryImplementation(String packagePrefix) {
String className = packagePrefix + ".el.ExpressionFactoryImpl";
try {
Class cl = ClassUtil.forName(className);
if(ExpressionFactory.class.isAssignableFrom(cl)) {
logger.info("Using " + className + " as implementation of " +
ExpressionFactory.class.getName());
return (ExpressionFactory)cl.newInstance();
}
logger.warn("Class " + className + " does not implement " +
ExpressionFactory.class.getName());
}
catch(ClassNotFoundException e) {
}
catch(Exception e) {
logger.error("Failed to instantiate " + className, e);
}
return null;
}
public void addELResolver(ELResolver resolver) {
additionalResolvers.add(resolver);
}
public ExpressionFactory getExpressionFactory() {
return expressionFactoryImpl;
}
ELContext createNewELContext(final FreeMarkerPageContext pageCtx) {
ELContext ctx = new FreeMarkerELContext(pageCtx);
ELContextEvent event = new ELContextEvent(ctx);
synchronized(listeners) {
for (Iterator iter = listeners.iterator(); iter.hasNext();) {
ELContextListener l = (ELContextListener) iter.next();
l.contextCreated(event);
}
}
return ctx;
}
private class FreeMarkerELContext extends ELContext {
private final FreeMarkerPageContext pageCtx;
FreeMarkerELContext(FreeMarkerPageContext pageCtx) {
this.pageCtx = pageCtx;
}
public ELResolver getELResolver() {
return elResolver;
}
public FunctionMapper getFunctionMapper() {
return null;
}
public VariableMapper getVariableMapper() {
return new VariableMapper() {
public ValueExpression resolveVariable(String name) {
Object obj = pageCtx.findAttribute(name);
if(obj == null) {
return null;
}
return expressionFactoryImpl.createValueExpression(obj,
obj.getClass());
}
public ValueExpression setVariable(String name,
ValueExpression value) {
ValueExpression prev = resolveVariable(name);
pageCtx.setAttribute(name, value.getValue(
FreeMarkerELContext.this));
return prev;
}
};
}
}
}
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