BAEL-7106-compress-and-uncompress-bytes-2 (#15398)

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/compressbytes/CompressByteArrayUtil.java

@@ -23,6 +23,23 @@ public class CompressByteArrayUtil {
         return outputStream.toByteArray();
     }
 
+    public static byte[] compressWithCustomLevel(byte[] input, int level) {
+        Deflater deflater = new Deflater();
+        deflater.setInput(input);
+        deflater.setLevel(level);
+        deflater.finish();
+
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        byte[] buffer = new byte[1024];
+
+        while (!deflater.finished()) {
+            int compressedSize = deflater.deflate(buffer);
+            outputStream.write(buffer, 0, compressedSize);
+        }
+
+        return outputStream.toByteArray();
+    }
+
     public static byte[] decompress(byte[] input) throws DataFormatException {
         Inflater inflater = new Inflater();
         inflater.setInput(input);

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/compressbytes/CompressByteArrayUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.compressbytes;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.zip.DataFormatException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class CompressByteArrayUnitTest {
+
+    private static final String INPUT_STRING = "Building a REST API is not a trivial task – from the high-level RESTful " +
+            "constraints down to the nitty-gritty of making everything work and work well." +
+            "Spring has made REST a first-class citizen and the platform has been maturing in leaps and bounds." +
+            "With this guide, my aim is to organize the mountains of information that are available on the subject and " +
+            "guide you through properly building an API." +
+            "The guide starts with the basics – bootstrapping the REST API, the Spring MVC Configuration, and basic customization.";
+
+    @Test
+    void givenInputString_whenCompressWithDefaultLevel_thenDecompressWithSameSize() throws DataFormatException {
+        byte[] input = INPUT_STRING.getBytes();
+        byte[] compressedData = CompressByteArrayUtil.compress(input);
+        byte[] decompressedData = CompressByteArrayUtil.decompress(compressedData);
+        System.out.println("Original: " + input.length + " bytes");
+        System.out.println("Compressed: " + compressedData.length + " bytes");
+        System.out.println("Decompressed: " + decompressedData.length + " bytes");
+        assertEquals(input.length, decompressedData.length);
+    }
+
+    @Test
+    void givenInputString_whenCompressWithCustomLevel_thenDecompressWithSameSize() throws DataFormatException {
+        byte[] input = INPUT_STRING.getBytes();
+        byte[] compressedData = CompressByteArrayUtil.compressWithCustomLevel(input, 1);
+        byte[] decompressedData = CompressByteArrayUtil.decompress(compressedData);
+        System.out.println("Original: " + input.length + " bytes");
+        System.out.println("Compressed: " + compressedData.length + " bytes");
+        System.out.println("Decompressed: " + decompressedData.length + " bytes");
+        assertEquals(input.length, decompressedData.length);
+    }
+}