org.culturegraph.mf.stream.sink.TripleObjectWriter.java Source code

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Here is the source code for org.culturegraph.mf.stream.sink.TripleObjectWriter.java

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/*
 *  Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 *  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.culturegraph.mf.stream.sink;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;
import org.culturegraph.mf.exceptions.MetafactureException;
import org.culturegraph.mf.framework.DefaultObjectReceiver;
import org.culturegraph.mf.framework.annotations.Description;
import org.culturegraph.mf.framework.annotations.In;
import org.culturegraph.mf.framework.annotations.Out;
import org.culturegraph.mf.types.Triple;

/**
 * Writes the object value of the triple into a file. The filename 
 * is constructed from subject and predicate.
 * 
 * Please note: This module does not check if the filename constructed
 * from subject and predicate stays within {@code baseDir}. THIS MODULE
 * SHOULD NOT BE USED IN ENVIRONMENTS IN WHICH THE VALUES OF SUBJECT AND
 * PREDICATE A PROVIDED BY AN UNTRUSTED SOURCE!
 * 
 * @author Christoph Bhme
 */
@Description("Writes the object value of the triple into a file. The filename is "
        + "constructed from subject and predicate. Please note: This module does "
        + "not check if the filename constructed from subject and predicate stays "
        + "within `baseDir`. THIS MODULE SHOULD NOT BE USED IN ENVIRONMENTS IN WHICH "
        + "THE VALUES OF SUBJECT AND PREDICATE A PROVIDED BY AN UNTRUSTED SOURCE!")
@In(Triple.class)
@Out(Void.class)
public final class TripleObjectWriter extends DefaultObjectReceiver<Triple> {

    private final String baseDir;

    private String encoding = "UTF-8";

    public TripleObjectWriter(final String baseDir) {
        this.baseDir = baseDir;
    }

    /**
     * Returns the encoding used to open the resource.
     * 
     * @return current default setting
     */
    public String getEncoding() {
        return encoding;
    }

    /**
     * Sets the encoding used to open the resource.
     * 
     * @param encoding
     *            new encoding
     */
    public void setEncoding(final String encoding) {
        this.encoding = encoding;
    }

    @Override
    public void process(final Triple triple) {
        final String file = FilenameUtils.concat(FilenameUtils.concat(baseDir, triple.getSubject()),
                triple.getPredicate());

        ensurePathExists(file);

        try {
            final Writer writer = new OutputStreamWriter(new FileOutputStream(file), encoding);
            IOUtils.write(triple.getObject(), writer);
            writer.close();
        } catch (IOException e) {
            throw new MetafactureException(e);
        }
    }

    private void ensurePathExists(final String path) {
        final File parent = new File(path).getAbsoluteFile().getParentFile();
        parent.mkdirs();
    }

}