org.directwebremoting.guice.InternalConverter Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
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/*
 * Copyright 2007 Tim Peierls
 *
 * 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.directwebremoting.guice;

import java.util.concurrent.atomic.AtomicBoolean;

import org.directwebremoting.ConversionException;
import org.directwebremoting.extend.AbstractConverter;
import org.directwebremoting.extend.Converter;
import org.directwebremoting.extend.ConverterManager;
import org.directwebremoting.extend.InboundVariable;
import org.directwebremoting.extend.OutboundContext;
import org.directwebremoting.extend.OutboundVariable;

import com.google.inject.Inject;
import com.google.inject.Provider;

/**
 * Specialized converter implementation that uses a Provider to
 * look up instances to delegate to. This class is used by
 * {@link InternalConverterManager}.
 * @author Tim Peierls [tim at peierls dot net]
 */
class InternalConverter extends AbstractConverter implements Converter
{
    /**
     * Only used to satisfy bindings for the two-arg {@code bindConversion}
     * method of {@link AbstractDwrModule}.
     */
    @Inject
    InternalConverter()
    {
        this.type = null;
        this.provider = null;
    }

    /**
     * Adapts a Provider into a Converter.
     */
    InternalConverter(Class type, Provider provider)
    {
        this.type = type;
        this.provider = provider;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.Converter#convertInbound(java.lang.Class, org.directwebremoting.extend.InboundVariable, org.directwebremoting.extend.InboundContext)
     */
    public Object convertInbound(Class typeInfo, InboundVariable data) throws ConversionException
    {
        try
        {
            return getConverter().convertInbound(typeInfo, data);
        }
        catch (ClassCastException e)
        {
            throw new ConversionException(type, e);
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.Converter#convertOutbound(java.lang.Object, org.directwebremoting.extend.OutboundContext)
     */
    public OutboundVariable convertOutbound(Object data, OutboundContext outctx) throws ConversionException
    {
        try
        {
            return getConverter().convertOutbound(type.cast(data), outctx);
        }
        catch (ClassCastException e)
        {
            throw new ConversionException(type, e);
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.convert.BaseV20Converter#setConverterManager(org.directwebremoting.extend.ConverterManager)
     */
    @Override
    public void setConverterManager(ConverterManager mgr)
    {
        this.converterManager = mgr;
    }


    private Converter getConverter()
    {
        Converter converter = provider.get();
        if (calledSetConverterManager.compareAndSet(false, true))
        {
            converter.setConverterManager(converterManager);
        }
        return converter;
    }


    private final Class type;

    private final Provider provider;

    private final AtomicBoolean calledSetConverterManager = new AtomicBoolean();

    private volatile ConverterManager converterManager;
}