ParamProcessorsService.java

/*****************************************************************************
 * Copyright 2011 Zdenko Vrabel
 *
 * Licensed 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.zdevra.guice.mvc.parameters;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Set;

import org.zdevra.guice.mvc.exceptions.InvalidMethodParameterException;

import com.google.inject.Inject;
import com.google.inject.Singleton;

/**
 * This class collect the all registered processor factories for parameters
 * which can be used and also the class choose the proper-one for the parameter.
 * 
 *  
 * @see ParamProcessorFactory
 * @see ParamProcessor
 */
@Singleton
public class ParamProcessorsService {

    private final Collection<ParamProcessorFactory> factories;

    /**
     * Constructor
     * @param factories are injected from Guice
     */
    @Inject
    public ParamProcessorsService(Set<ParamProcessorFactory> factories) {
        this.factories = new ArrayList<ParamProcessorFactory>(factories);
    }


    public ParamProcessor createProcessor(ParamMetadata metadata) {
        for (ParamProcessorFactory factory : factories) {
            ParamProcessor processor = factory.buildParamProcessor(metadata);
            if (processor != null) {
                return processor;
            }
        }

        throw new InvalidMethodParameterException(metadata);
    }
}