Tomcat example source code file (ListELResolver.java)

This example Tomcat source code file (ListELResolver.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, boolean, class, elexception, featuredescriptor, javabean, list, list, listelresolver, nullpointerexception, nullpointerexception, object, object, propertynotfoundexception, propertynotfoundexception, propertynotwritableexception, util

The Tomcat ListELResolver.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.el;

import java.beans.FeatureDescriptor;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public class ListELResolver extends ELResolver {

	private final boolean readOnly;

	private final static Class UNMODIFIABLE = Collections.unmodifiableList(
			new ArrayList()).getClass();

	public ListELResolver() {
		this.readOnly = false;
	}

	public ListELResolver(boolean readOnly) {
		this.readOnly = readOnly;
	}

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

		if (base instanceof List) {
			context.setPropertyResolved(true);
			List list = (List) base;
			int idx = coerce(property);
			if (idx < 0 || idx >= list.size()) {
				return null;
			}
			return list.get(idx);
		}

		return null;
	}

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

		if (base instanceof List) {
			context.setPropertyResolved(true);
			List list = (List) base;
			int idx = coerce(property);
			if (idx < 0 || idx >= list.size()) {
				return null;
			}
			Object obj = list.get(idx);
			return (obj != null) ? obj.getClass() : null;
		}

		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 instanceof List) {
			context.setPropertyResolved(true);
			List list = (List) base;

			if (this.readOnly) {
				throw new PropertyNotWritableException(message(context,
						"resolverNotWriteable", new Object[] { base.getClass()
								.getName() }));
			}

			int idx = coerce(property);
			try {
				list.set(idx, value);
			} catch (UnsupportedOperationException e) {
				throw new PropertyNotWritableException(e);
			} catch (IndexOutOfBoundsException e) {
				throw new PropertyNotFoundException(e);
			}
		}
	}

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

		if (base instanceof List) {
			context.setPropertyResolved(true);
			List list = (List) base;
			int idx = coerce(property);
			if (idx < 0 || idx >= list.size()) {
				throw new PropertyNotFoundException(
						new ArrayIndexOutOfBoundsException(idx).getMessage());
			}
			return this.readOnly || UNMODIFIABLE.equals(list.getClass());
		}

		return this.readOnly;
	}

	public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
		if (base instanceof List) {
			FeatureDescriptor[] descs = new FeatureDescriptor[((List) base).size()];
			for (int i = 0; i < descs.length; i++) {
				descs[i] = new FeatureDescriptor();
				descs[i].setDisplayName("["+i+"]");
				descs[i].setExpert(false);
				descs[i].setHidden(false);
				descs[i].setName(""+i);
				descs[i].setPreferred(true);
				descs[i].setValue(RESOLVABLE_AT_DESIGN_TIME, Boolean.FALSE);
				descs[i].setValue(TYPE, Integer.class);
			}
			return Arrays.asList(descs).iterator();
		}
		return null;
	}

	public Class<?> getCommonPropertyType(ELContext context, Object base) {
		if (base != null && base instanceof List) {
			return Integer.class;
		}
		return null;
	}

	private final static int coerce(Object property) {
		if (property instanceof Number) {
			return ((Number) property).intValue();
		}
		if (property instanceof Character) {
			return ((Character) property).charValue();
		}
		if (property instanceof Boolean) {
			return (((Boolean) property).booleanValue() ? 1 : 0);
		}
        if (property instanceof String) {
            return Integer.parseInt((String) property);
        }
		throw new IllegalArgumentException(property != null ? property
				.toString() : "null");
	}
}