Tomcat example source code file (JspApplicationContextImpl.java)

This example Tomcat source code file (JspApplicationContextImpl.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

arraylist, compositeelresolver, elcontextevent, elcontextimpl, elcontextimpl, elresolver, elresolver, expressionfactory, http, illegalargumentexception, illegalargumentexception, illegalstateexception, jsp, jspapplicationcontextimpl, jspapplicationcontextimpl, list, servlet, util

The Tomcat JspApplicationContextImpl.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 org.apache.jasper.runtime;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import javax.el.ArrayELResolver;
import javax.el.BeanELResolver;
import javax.el.CompositeELResolver;
import javax.el.ELContextEvent;
import javax.el.ELContextListener;
import javax.el.ELResolver;
import javax.el.ExpressionFactory;
import javax.el.ListELResolver;
import javax.el.MapELResolver;
import javax.el.ResourceBundleELResolver;
import javax.servlet.ServletContext;
import javax.servlet.jsp.JspApplicationContext;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.el.ImplicitObjectELResolver;
import javax.servlet.jsp.el.ScopedAttributeELResolver;

import org.apache.el.ExpressionFactoryImpl;
import org.apache.jasper.el.ELContextImpl;

/**
 * Implementation of JspApplicationContext
 * 
 * @author Jacob Hookom
 */
public class JspApplicationContextImpl implements JspApplicationContext {

	private final static String KEY = JspApplicationContextImpl.class.getName();

	private final static ExpressionFactory expressionFactory = new ExpressionFactoryImpl();

	private final List<ELContextListener> contextListeners = new ArrayList();

	private final List<ELResolver> resolvers = new ArrayList();

	private boolean instantiated = false;

	private ELResolver resolver;

	public JspApplicationContextImpl() {

	}

	public void addELContextListener(ELContextListener listener) {
		if (listener == null) {
			throw new IllegalArgumentException("ELConextListener was null");
		}
		this.contextListeners.add(listener);
	}

	public static JspApplicationContextImpl getInstance(ServletContext context) {
		if (context == null) {
			throw new IllegalArgumentException("ServletContext was null");
		}
		JspApplicationContextImpl impl = (JspApplicationContextImpl) context
				.getAttribute(KEY);
		if (impl == null) {
			impl = new JspApplicationContextImpl();
			context.setAttribute(KEY, impl);
		}
		return impl;
	}

	public ELContextImpl createELContext(JspContext context) {
		if (context == null) {
			throw new IllegalArgumentException("JspContext was null");
		}

		// create ELContext for JspContext
		ELResolver r = this.createELResolver();
		ELContextImpl ctx = new ELContextImpl(r);
		ctx.putContext(JspContext.class, context);

		// alert all ELContextListeners
		ELContextEvent event = new ELContextEvent(ctx);
		for (int i = 0; i < this.contextListeners.size(); i++) {
			this.contextListeners.get(i).contextCreated(event);
		}

		return ctx;
	}

	private ELResolver createELResolver() {
		this.instantiated = true;
		if (this.resolver == null) {
			CompositeELResolver r = new CompositeELResolver();
			r.add(new ImplicitObjectELResolver());
			for (Iterator itr = this.resolvers.iterator(); itr.hasNext();) {
				r.add((ELResolver) itr.next());
			}
			r.add(new MapELResolver());
			r.add(new ResourceBundleELResolver());
			r.add(new ListELResolver());
			r.add(new ArrayELResolver());	
			r.add(new BeanELResolver());
			r.add(new ScopedAttributeELResolver());
			this.resolver = r;
		}
		return this.resolver;
	}

	public void addELResolver(ELResolver resolver) throws IllegalStateException {
		if (resolver == null) {
			throw new IllegalArgumentException("ELResolver was null");
		}
		if (this.instantiated) {
			throw new IllegalStateException(
					"cannot call addELResolver after the first request has been made");
		}
		this.resolvers.add(resolver);
	}

	public ExpressionFactory getExpressionFactory() {
		return expressionFactory;
	}

}