Merge pull request #69 from cboehme/triple-object-writer

Added TripleObjectWriter module to write the object values of triples into files.

Author: cboehme

src/main/java/org/culturegraph/mf/stream/sink/TripleObjectWriter.java

@@ -0,0 +1,99 @@
+/*
+ *  Copyright 2013 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.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 Böhme
+ */
+@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)
+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();
+	}
+	
+}

src/test/java/org/culturegraph/mf/stream/sink/TripleObjectWriterTest.java

@@ -0,0 +1,95 @@
+/*
+ *  Copyright 2013 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 static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.commons.io.IOUtils;
+import org.culturegraph.mf.types.Triple;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+/**
+ * Tests for {@link TripleObjectWriter}.
+ * 
+ * @author Christoph Böhme
+ */
+public final class TripleObjectWriterTest {
+
+	private static final String SUBJECT1 = "subject1";
+	private static final String SUBJECT2 = "subject2";
+	private static final String STRUCTURED_SUBJECT_A = "a";
+	private static final String STRUCTURED_SUBJECT_B = "b";
+	private static final String STRUCTURED_SUBJECT = STRUCTURED_SUBJECT_A + "/" + STRUCTURED_SUBJECT_B;
+	private static final String PREDICATE = "predicate";
+	private static final String OBJECT1 = "object-data 1";
+	private static final String OBJECT2 = "object-data 2";
+
+	private TripleObjectWriter tripleObjectWriter;
+	
+	// NO CHECKSTYLE VisibilityModifier|DeclarationOrder FOR 3 LINES:
+	// JUnit requires rules to be public
+	@Rule
+	public TemporaryFolder tempFolder = new TemporaryFolder();
+	
+	private String baseDir;
+
+	@Before
+	public void setup() throws IOException {
+		baseDir = tempFolder.newFolder().getAbsolutePath();
+		tripleObjectWriter = new TripleObjectWriter(baseDir);
+	}
+	
+	@After
+	public void cleanup() {
+		tripleObjectWriter.closeStream();
+	}
+	
+	@Test
+	public void testShouldWriteObjectOfTripleIntoFile() throws IOException {
+		tripleObjectWriter.process(new Triple(SUBJECT1, PREDICATE, OBJECT1));
+		tripleObjectWriter.process(new Triple(SUBJECT2, PREDICATE, OBJECT2));
+		
+		final String filename1 = baseDir + File.separator + SUBJECT1 + File.separator + PREDICATE;
+		final String filename2 = baseDir + File.separator + SUBJECT2 + File.separator + PREDICATE;
+		assertEquals(get(filename1), OBJECT1);
+		assertEquals(get(filename2), OBJECT2);
+	}
+	
+	@Test
+	public void testShouldMapStructuredSubjectsToDirectories() throws IOException {
+		tripleObjectWriter.process(new Triple(STRUCTURED_SUBJECT, PREDICATE, OBJECT1));
+		
+		final String filename = baseDir
+				+ File.separator + STRUCTURED_SUBJECT_A + File.separator + STRUCTURED_SUBJECT_B 
+				+ File.separator + PREDICATE;
+		assertEquals(get(filename), OBJECT1);		
+	}
+	
+	private String get(final String filename) throws IOException {
+		final InputStream stream = new FileInputStream(filename);
+		return IOUtils.toString(stream, tripleObjectWriter.getEncoding());
+	}
+	
+}