ExpressionAdapter.java

/**
 * 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.camel.support;

import org.apache.camel.Exchange;

/**
 * A helper class for developers wishing to implement an {@link org.apache.camel.Expression}
 * using Java code with a minimum amount of code to write so that the developer only needs
 * to implement one of the {@link #evaluate(org.apache.camel.Exchange, Class)} or
 * {@link #evaluate(org.apache.camel.Exchange)} methods.
 *
 * @version 
 */
public abstract class ExpressionAdapter extends ExpressionSupport {

    protected String assertionFailureMessage(Exchange exchange) {
        return toString();
    }

    public <T> T evaluate(Exchange exchange, Class<T> type) {
        Object value = evaluate(exchange);
        if (Object.class == type) {
            // do not use type converter if type is Object (optimize)
            return (T) value;
        }
        return exchange.getContext().getTypeConverter().convertTo(type, exchange, value);
    }

}