Implementation compression module

compression/build.gradle

@@ -13,3 +13,6 @@ dependencies {
 	testImplementation 'org.junit.jupiter:junit-jupiter-api:5.10.2'
 	testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.10.2'
 }
+tasks.named('test', Test) {
+	useJUnitPlatform()
+}

compression/src/main/java/de/afrouper/compression/NumberCompression.java

@@ -0,0 +1,55 @@
+package de.afrouper.compression;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+
+public class NumberCompression {
+
+    private static final byte BYTES_SHORT = 2;
+    private static final byte BYTES_INTEGER = 4;
+
+    private final Base64.Encoder encoder = Base64.getEncoder();
+    private final Base64.Decoder decoder = Base64.getDecoder();
+
+    public String compressShort(short[] numbers) {
+        byte[] bytes = new byte[numbers.length * BYTES_SHORT];
+        for (int numberIndex = 0, byteIndex = 0; numberIndex < numbers.length; numberIndex++, byteIndex = byteIndex + BYTES_SHORT) {
+            bytes[byteIndex] = (byte)(numbers[numberIndex] >> 8);
+            bytes[byteIndex+1] = (byte)numbers[numberIndex];
+        }
+        return encoder.encodeToString(bytes);
+    }
+
+    public String compressInteger(int[] numbers) {
+        byte[] bytes = new byte[numbers.length * BYTES_INTEGER];
+        for (int numberIndex = 0, byteIndex = 0; numberIndex < numbers.length; numberIndex++, byteIndex = byteIndex + BYTES_INTEGER) {
+            bytes[byteIndex] = (byte)(numbers[numberIndex] >> 24);
+            bytes[byteIndex+1] = (byte)(numbers[numberIndex] >> 16);
+            bytes[byteIndex+2] = (byte)(numbers[numberIndex] >> 8);
+            bytes[byteIndex+3] = (byte)numbers[numberIndex];
+        }
+        return encoder.encodeToString(bytes);
+    }
+
+    public short[] uncompressShort(String data) {
+        byte[] bytes = decoder.decode(data.getBytes(StandardCharsets.UTF_8));
+        short[] numbers = new short[bytes.length / BYTES_SHORT];
+        for (int numberIndex = 0, byteIndex = 0; numberIndex < numbers.length; numberIndex++, byteIndex = byteIndex + BYTES_SHORT) {
+            numbers[numberIndex] = (short) (((bytes[byteIndex] & 0xFF) << 8 ) | (bytes[byteIndex+1] & 0xFF) );
+        }
+        return numbers;
+    }
+
+    public int[] uncompressInteger(String data) {
+        byte[] bytes = decoder.decode(data.getBytes(StandardCharsets.UTF_8));
+        int[] numbers = new int[bytes.length / BYTES_INTEGER];
+        for (int numberIndex = 0, byteIndex = 0; numberIndex < numbers.length; numberIndex++, byteIndex = byteIndex + BYTES_INTEGER) {
+            numbers[numberIndex] = (
+                    ((bytes[byteIndex] & 0xFF) << 24 ) |
+                    ((bytes[byteIndex+1] & 0xFF) << 16 ) |
+                    ((bytes[byteIndex+2] & 0xFF) << 8 ) |
+                    (bytes[byteIndex+3] & 0xFF));
+        }
+        return numbers;
+    }
+}

compression/src/test/java/de/afrouper/compression/NumberCompressionTest.java

@@ -0,0 +1,31 @@
+package de.afrouper.compression;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class NumberCompressionTest {
+
+    private static final short[] NUMBERS_SHORT = new short[]{4711,815,88,1,9999,8000,7514,6941,1254,-500,0};
+    private static final int[] NUMBERS_INTEGER = new int[]{4711,815,88,1,9999,8000,7514,6941,1254, 326547,-500,0};
+
+    private final NumberCompression numberCompression = new NumberCompression();
+
+    @Test
+    void testCompressionCycleShort() {
+        String compressed = numberCompression.compressShort(NUMBERS_SHORT);
+        assertNotNull(compressed);
+        System.out.println("Bytes: " + compressed.length());
+        short[] uncompressed = numberCompression.uncompressShort(compressed);
+        assertArrayEquals(NUMBERS_SHORT, uncompressed);
+    }
+
+    @Test
+    void testCompressionCycleInteger() {
+        String compressed = numberCompression.compressInteger(NUMBERS_INTEGER);
+        assertNotNull(compressed);
+        System.out.println("Bytes: " + compressed.length());
+        int[] uncompressed = numberCompression.uncompressInteger(compressed);
+        assertArrayEquals(NUMBERS_INTEGER, uncompressed);
+    }
+}

settings.gradle

@@ -1,8 +1,8 @@
-rootProject.name = 'Playground'
+rootProject.name = 'playground'
 
+include 'compression'
 include 'BCEL'
 include 'backtracking'
 include 'jzos_batch'
 include 'JNI'
 include 'xmp'
-include 'compression'