org.ssoup.backend.web.RdfModelConverter.java Source code

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Here is the source code for org.ssoup.backend.web.RdfModelConverter.java

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/*
 * Copyright 2012  Research Studios Austria Forschungsges.m.b.H.
 *
 *    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.ssoup.backend.web;

import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import org.apache.jena.atlas.web.ContentType;
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFDataMgr;
import org.apache.jena.riot.RDFLanguages;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;

import java.io.IOException;
import java.util.Collection;

/**
 * HttpMessageConverter for using jena models with Spring WebMVC. Supports all formats jena supports
 */
public class RdfModelConverter extends AbstractHttpMessageConverter<Model> {
    private static final Logger logger = LoggerFactory.getLogger(RdfModelConverter.class);

    public RdfModelConverter() {
        this(buildMediaTypeArray());
    }

    public RdfModelConverter(MediaType supportedMediaType) {
        super(supportedMediaType);
    }

    public RdfModelConverter(MediaType... supportedMediaTypes) {
        super(supportedMediaTypes);
    }

    @Override
    protected boolean supports(Class<?> clazz) {
        return Model.class.isAssignableFrom(clazz);
    }

    @Override
    protected Model readInternal(Class<? extends Model> aClass, HttpInputMessage httpInputMessage)
            throws IOException, HttpMessageNotReadableException {
        Model model = ModelFactory.createDefaultModel();
        Lang rdfLanguage = mimeTypeToJenaLanguage(httpInputMessage.getHeaders().getContentType(), Lang.JSONLD);
        RDFDataMgr.read(model, httpInputMessage.getBody(), "", rdfLanguage);
        return model;
    }

    @Override
    protected void writeInternal(Model model, HttpOutputMessage httpOutputMessage)
            throws IOException, HttpMessageNotWritableException {
        Lang rdfLanguage = mimeTypeToJenaLanguage(httpOutputMessage.getHeaders().getContentType(), Lang.JSONLD);
        RDFDataMgr.write(httpOutputMessage.getBody(), model, rdfLanguage);
        httpOutputMessage.getBody().flush();
    }

    private static Lang mimeTypeToJenaLanguage(MediaType mediaType, Lang defaultLanguage) {
        Lang lang = RDFLanguages.contentTypeToLang(mediaType.toString());
        if (lang == null)
            return defaultLanguage;
        return lang;
    }

    private static MediaType[] buildMediaTypeArray() {
        // now register the media types this converter can handle
        Collection<Lang> languages = RDFLanguages.getRegisteredLanguages();
        MediaType[] mediatypes = new MediaType[languages.size()];

        int i = 0;
        for (Lang lang : languages) {
            ContentType ct = lang.getContentType();
            logger.debug("registering converter for rdf content type {}", lang.getContentType());
            MediaType mt = new MediaType(ct.getType(), ct.getSubType());
            mediatypes[i++] = mt;
        }
        return mediatypes;
    }
}