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Tomcat example source code file (ExpressionEvaluatorImpl.java)

This example Tomcat source code file (ExpressionEvaluatorImpl.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

class, class, elcontextimpl, elexception, elexception, expressionevaluator, expressionevaluatorimpl, expressionevaluatorimpl, expressionfactory, functionmapper, functionmapper, functionmapperimpl, jsp, object, servlet, variableresolver

The Tomcat ExpressionEvaluatorImpl.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.el;

import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.servlet.jsp.el.ELException;
import javax.servlet.jsp.el.ELParseException;
import javax.servlet.jsp.el.Expression;
import javax.servlet.jsp.el.ExpressionEvaluator;
import javax.servlet.jsp.el.FunctionMapper;
import javax.servlet.jsp.el.VariableResolver;


public final class ExpressionEvaluatorImpl extends ExpressionEvaluator {

	private final ExpressionFactory factory;
	
	public ExpressionEvaluatorImpl(ExpressionFactory factory) {
		this.factory = factory;
	}

	public Expression parseExpression(String expression, Class expectedType,
			FunctionMapper fMapper) throws ELException {
		try {
			ELContextImpl ctx = new ELContextImpl(ELResolverImpl.DefaultResolver);
            if (fMapper != null) {
                ctx.setFunctionMapper(new FunctionMapperImpl(fMapper));
            }
			ValueExpression ve = this.factory.createValueExpression(ctx, expression, expectedType);
			return new ExpressionImpl(ve);
		} catch (javax.el.ELException e) {
			throw new ELParseException(e.getMessage());
		}
	}

	public Object evaluate(String expression, Class expectedType,
			VariableResolver vResolver, FunctionMapper fMapper)
			throws ELException {
		return this.parseExpression(expression, expectedType, fMapper).evaluate(vResolver);
	}

}

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