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Tomcat example source code file (CompositeELResolver.java)

This example Tomcat source code file (CompositeELResolver.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, compositeelresolver, elexception, elresolver, elresolver, featuredescriptor, featureiterator, iterator, javabean, nullpointerexception, nullpointerexception, object, object, propertynotfoundexception, propertynotfoundexception, util

The Tomcat CompositeELResolver.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.Iterator;

public class CompositeELResolver extends ELResolver {

	private int size;

	private ELResolver[] resolvers;

	public CompositeELResolver() {
		this.size = 0;
		this.resolvers = new ELResolver[2];
	}

	public void add(ELResolver elResolver) {
		if (elResolver == null) {
			throw new NullPointerException();
		}

		if (this.size >= this.resolvers.length) {
			ELResolver[] nr = new ELResolver[this.size * 2];
			System.arraycopy(this.resolvers, 0, nr, 0, this.size);
			this.resolvers = nr;
		}
		this.resolvers[this.size++] = elResolver;
	}

	public Object getValue(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		context.setPropertyResolved(false);
		int sz = this.size;
		Object result = null;
		for (int i = 0; i < sz; i++) {
			result = this.resolvers[i].getValue(context, base, property);
			if (context.isPropertyResolved()) {
				return result;
			}
		}
		return null;
	}

	public void setValue(ELContext context, Object base, Object property,
			Object value) throws NullPointerException,
			PropertyNotFoundException, PropertyNotWritableException,
			ELException {
		context.setPropertyResolved(false);
		int sz = this.size;
		for (int i = 0; i < sz; i++) {
			this.resolvers[i].setValue(context, base, property, value);
			if (context.isPropertyResolved()) {
				return;
			}
		}
	}

	public boolean isReadOnly(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		context.setPropertyResolved(false);
		int sz = this.size;
		boolean readOnly = false;
		for (int i = 0; i < sz; i++) {
			readOnly = this.resolvers[i].isReadOnly(context, base, property);
			if (context.isPropertyResolved()) {
				return readOnly;
			}
		}
		return false;
	}

	public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
		return new FeatureIterator(context, base, this.resolvers, this.size);
	}

	public Class<?> getCommonPropertyType(ELContext context, Object base) {
		int sz = this.size;
		Class<?> commonType = null, type = null;
		for (int i = 0; i < sz; i++) {
			type = this.resolvers[i].getCommonPropertyType(context, base);
			if (type != null
					&& (commonType == null || commonType.isAssignableFrom(type))) {
				commonType = type;
			}
		}
		return commonType;
	}

	public Class<?> getType(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		context.setPropertyResolved(false);
		int sz = this.size;
		Class<?> type;
		for (int i = 0; i < sz; i++) {
			type = this.resolvers[i].getType(context, base, property);
			if (context.isPropertyResolved()) {
				return type;
			}
		}
		return null;
	}

	private final static class FeatureIterator implements Iterator<FeatureDescriptor> {

		private final ELContext context;

		private final Object base;

		private final ELResolver[] resolvers;

		private final int size;

		private Iterator itr;

		private int idx;

		public FeatureIterator(ELContext context, Object base,
				ELResolver[] resolvers, int size) {
			this.context = context;
			this.base = base;
			this.resolvers = resolvers;
			this.size = size;

			this.idx = 0;
			this.guaranteeIterator();
		}
		
		private void guaranteeIterator() {
			while (this.itr == null && this.idx < this.size) {
				this.itr = this.resolvers[this.idx].getFeatureDescriptors(
						this.context, this.base);
				this.idx++;
			}
		}

		public boolean hasNext() {
			return this.itr != null;
		}

		public FeatureDescriptor next() {
			Object result = null;
			if (this.itr != null) {
				if (this.itr.hasNext()) {
					result = this.itr.next();
					if (!this.itr.hasNext()) {
						this.itr = null;
						this.guaranteeIterator();
					}
				}
			}
			return (FeatureDescriptor) result;
		}

		public void remove() {
			throw new UnsupportedOperationException();
		}
	}

}

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