Added JarUtils: programatically extract JAR files.

src/main/com/jdbernard/util/JarUtils.groovy

@@ -0,0 +1,36 @@
+package com.jdbernard.util
+
+import java.util.jar.JarEntry
+import java.util.jar.JarFile
+import java.util.jar.JarInputStream
+import java.util.jar.JarOutputStream
+
+public class JarUtils {
+
+    public static void extract(File f, File outputDir) {
+        extract(new JarFile(f), outputDir) }
+
+    public static void extract(JarFile jarFile, File outputDir) {
+        jarFile.entries().each { jarEntry ->
+            def outputFile = new File(outputDir, jarEntry.name)
+            if (jarEntry.isDirectory()) { outputFile.mkdirs() }
+            else {
+                jarFile.getInputStream(jarEntry).withStream { is ->
+                    outputFile.withOutputStream { os ->
+                        while (is.available() > 0) { os.write(is.read()) }}}}}}
+
+    public static void extract(JarInputStream jarIS, File outputDir) {
+        JarEntry curEntry = jarIS.nextJarEntry
+        while(curEntry != null) {
+            File outFile = new File(outputDir, curEntry.name)
+            if (curEntry.isDirectory()) { outFile.mkdirs() }
+            else {
+                outFile.withOutputStream { os ->
+                    byte[] buffer = new byte[curEntry.size]
+                    int bytesRead = jarIS.read(buffer, 0, curEntry.size as
+                    Integer)
+                    os.write(buffer, 0, bytesRead) }}
+            
+            curEntry = jarIS.nextJarEntry }
+        jarIS.close() }
+}