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Tomcat example source code file (ScopedAttributeELResolver.java)

This example Tomcat source code file (ScopedAttributeELResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

bean, class, elexception, enumeration, featuredescriptor, featuredescriptor, http, javabean, nullpointerexception, nullpointerexception, object, object, pagecontext, propertynotfoundexception, scopedattributeelresolver, servlet, string, string, util

The Tomcat ScopedAttributeELResolver.java source code

/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package javax.servlet.jsp.el;

import java.beans.FeatureDescriptor;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.el.PropertyNotFoundException;
import javax.el.PropertyNotWritableException;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.PageContext;

public class ScopedAttributeELResolver extends ELResolver {

	public ScopedAttributeELResolver() {
		super();
	}

	public Object getValue(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		if (context == null) {
			throw new NullPointerException();
		}

		if (base == null) {
			context.setPropertyResolved(true);
			if (property != null) {
				String key = property.toString();
				PageContext page = (PageContext) context
						.getContext(JspContext.class);
				return page.findAttribute(key);
			}
		}

		return null;
	}

	public Class<Object> getType(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		if (context == null) {
			throw new NullPointerException();
		}

		if (base == null) {
			context.setPropertyResolved(true);
			return Object.class;
		}

		return null;
	}

	public void setValue(ELContext context, Object base, Object property,
			Object value) throws NullPointerException,
			PropertyNotFoundException, PropertyNotWritableException,
			ELException {
		if (context == null) {
			throw new NullPointerException();
		}

		if (base == null) {
			context.setPropertyResolved(true);
			if (property != null) {
				String key = property.toString();
				PageContext page = (PageContext) context
						.getContext(JspContext.class);
				int scope = page.getAttributesScope(key);
				if (scope != 0) {
					page.setAttribute(key, value, scope);
				} else {
					page.setAttribute(key, value);
				}
			}
		}
	}

	public boolean isReadOnly(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		if (context == null) {
			throw new NullPointerException();
		}

		if (base == null) {
			context.setPropertyResolved(true);
		}

		return false;
	}

	public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {

		PageContext ctxt = (PageContext) context.getContext(JspContext.class);
		List<FeatureDescriptor> list = new ArrayList();
		Enumeration e;
		Object value;
		String name;

		e = ctxt.getAttributeNamesInScope(PageContext.PAGE_SCOPE);
		while (e.hasMoreElements()) {
			name = (String) e.nextElement();
			value = ctxt.getAttribute(name, PageContext.PAGE_SCOPE);
			FeatureDescriptor descriptor = new FeatureDescriptor();
			descriptor.setName(name);
			descriptor.setDisplayName(name);
			descriptor.setExpert(false);
			descriptor.setHidden(false);
			descriptor.setPreferred(true);
			descriptor.setShortDescription("page scoped attribute");
			descriptor.setValue("type", value.getClass());
			descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
			list.add(descriptor);
		}

		e = ctxt.getAttributeNamesInScope(PageContext.REQUEST_SCOPE);
		while (e.hasMoreElements()) {
			name = (String) e.nextElement();
			value = ctxt.getAttribute(name, PageContext.REQUEST_SCOPE);
			FeatureDescriptor descriptor = new FeatureDescriptor();
			descriptor.setName(name);
			descriptor.setDisplayName(name);
			descriptor.setExpert(false);
			descriptor.setHidden(false);
			descriptor.setPreferred(true);
			descriptor.setShortDescription("request scope attribute");
			descriptor.setValue("type", value.getClass());
			descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
			list.add(descriptor);
		}

		if (ctxt.getSession() != null) {
			e = ctxt.getAttributeNamesInScope(PageContext.SESSION_SCOPE);
			while (e.hasMoreElements()) {
				name = (String) e.nextElement();
				value = ctxt.getAttribute(name, PageContext.SESSION_SCOPE);
				FeatureDescriptor descriptor = new FeatureDescriptor();
				descriptor.setName(name);
				descriptor.setDisplayName(name);
				descriptor.setExpert(false);
				descriptor.setHidden(false);
				descriptor.setPreferred(true);
				descriptor.setShortDescription("session scoped attribute");
				descriptor.setValue("type", value.getClass());
				descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
				list.add(descriptor);
			}
		}

		e = ctxt.getAttributeNamesInScope(PageContext.APPLICATION_SCOPE);
		while (e.hasMoreElements()) {
			name = (String) e.nextElement();
			value = ctxt.getAttribute(name, PageContext.APPLICATION_SCOPE);
			FeatureDescriptor descriptor = new FeatureDescriptor();
			descriptor.setName(name);
			descriptor.setDisplayName(name);
			descriptor.setExpert(false);
			descriptor.setHidden(false);
			descriptor.setPreferred(true);
			descriptor.setShortDescription("application scoped attribute");
			descriptor.setValue("type", value.getClass());
			descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
			list.add(descriptor);
		}
		return list.iterator();
	}

	private static void appendEnumeration(Collection c, Enumeration e) {
		while (e.hasMoreElements()) {
			c.add(e.nextElement());
		}
	}

	public Class<String> getCommonPropertyType(ELContext context, Object base) {
		if (base == null) {
			return String.class;
		}
		return null;
	}
}

Other Tomcat examples (source code examples)

Here is a short list of links related to this Tomcat ScopedAttributeELResolver.java source code file:

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