fixed gzip and tests

src/main/java/eu/dnetlib/apps/oai/utils/GzipUtils.java

@@ -1,37 +1,54 @@
 package eu.dnetlib.apps.oai.utils;
 
+import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.InputStreamReader;
 import java.util.zip.GZIPInputStream;
 import java.util.zip.GZIPOutputStream;
 
-import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang3.StringUtils;
 
 public class GzipUtils {
 
-	public static byte[] compress(final String data) {
-		if (StringUtils.isBlank(data)) { return null; }
+	public static byte[] compress(final String str) {
+		if (StringUtils.isBlank(str)) { return null; }
 
-		try (final ByteArrayOutputStream bos = new ByteArrayOutputStream(data.length());
-			final GZIPOutputStream gzip = new GZIPOutputStream(bos)) {
-			gzip.write(data.getBytes());
+		try {
+			final ByteArrayOutputStream obj = new ByteArrayOutputStream();
+			final GZIPOutputStream gzip = new GZIPOutputStream(obj);
+			gzip.write(str.getBytes("UTF-8"));
 			gzip.flush();
-			return bos.toByteArray();
+			gzip.close();
+			return obj.toByteArray();
 		} catch (final IOException e) {
 			throw new RuntimeException("error in gzip", e);
 		}
 	}
 
-	public static String decompress(final byte[] bytes) {
-		if (bytes == null || bytes.length == 0) { return null; }
-		try (final ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
-			final GZIPInputStream gis = new GZIPInputStream(bis)) {
-			return IOUtils.toString(gis, "UTF-8");
+	public static String decompress(final byte[] compressed) {
+		final StringBuilder outStr = new StringBuilder();
+		if (compressed == null || compressed.length == 0) { return null; }
+		try {
+			if (isCompressed(compressed)) {
+				final GZIPInputStream gis = new GZIPInputStream(new ByteArrayInputStream(compressed));
+				final BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(gis, "UTF-8"));
+
+				String line;
+				while ((line = bufferedReader.readLine()) != null) {
+					outStr.append(line);
+				}
+			} else {
+				outStr.append(compressed);
+			}
+			return outStr.toString();
 		} catch (final IOException e) {
 			throw new RuntimeException("error in gunzip", e);
 		}
 	}
 
+	public static boolean isCompressed(final byte[] compressed) {
+		return compressed[0] == (byte) GZIPInputStream.GZIP_MAGIC && compressed[1] == (byte) (GZIPInputStream.GZIP_MAGIC >> 8);
+	}
 }

src/test/java/eu/dnetlib/apps/oai/utils/GzipUtilsTest.java

@@ -0,0 +1,47 @@
+package eu.dnetlib.apps.oai.utils;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class GzipUtilsTest {
+
+	@BeforeEach
+	void setUp() throws Exception {}
+
+	@Test
+	final void testCompressAndDecompress() {
+		final String message = "Hello world";
+
+		final byte[] bytes = GzipUtils.compress(message);
+		assertNotNull(bytes);
+		assertTrue(bytes.length > 0);
+
+		assertEquals(message, GzipUtils.decompress(bytes));
+	}
+
+	@Test
+	final void testCompressNull() {
+		assertNull(GzipUtils.compress(null));
+	}
+
+	@Test
+	final void testDecompressNull() {
+		assertNull(GzipUtils.decompress(null));
+	}
+
+	@Test
+	final void testCompressEmpty() {
+		assertNull(GzipUtils.compress(""));
+	}
+
+	@Test
+	final void testDecompressEmpty() {
+		assertNull(GzipUtils.decompress(new byte[] {}));
+	}
+
+}