First commit.

src/main/kotlin/com/example/Main.kt

@@ -0,0 +1,84 @@
+package com.example
+
+import org.apache.commons.compress.archivers.zip.*
+import java.io.File
+import java.util.*
+
+internal var allFilesPredicate: ZipArchiveEntryPredicate = ZipArchiveEntryPredicate { true }
+
+fun main(args: Array<String>) {
+    val kobalt = File("kobalt-1.0.58.jar")
+    val zip = File("kobalt-1.0.58.zip")
+    val src = File("kobalt-1.0.58-sources.jar")
+
+    //rezip2(kobalt, zip)
+    rezip3(kobalt, src, zip)
+}
+
+fun rezip(jarIn: File, zipOut: File) {
+    val s = System.currentTimeMillis()
+    val zos = ZipArchiveOutputStream(zipOut)
+    zos.encoding = "UTF-8"
+    val zip = ZipFile(jarIn)
+    zip.copyRawEntries(zos, allFilesPredicate)
+    zos.close()
+    zip.close()
+
+    println("Rezip Time: " + (System.currentTimeMillis() - s) + "ms")
+}
+
+fun rezip2(jarIn: File, zipOut: File) {
+    val s = System.currentTimeMillis()
+    val zos = ZipArchiveOutputStream(zipOut)
+    zos.encoding = "UTF-8"
+    val zip = ZipFile(jarIn)
+
+    for (entry in zip.entries) {
+        zos.addRawArchiveEntry(entry, zip.getRawInputStream(entry))
+    }
+
+    zos.close()
+
+    zip.close()
+
+    println("Rezip2 Time: " + (System.currentTimeMillis() - s) + "ms")
+}
+
+fun rezip3(jarIn: File, srcJar: File, zipOut: File) {
+    val s = System.currentTimeMillis()
+    val zos = ZipArchiveOutputStream(zipOut)
+    zos.encoding = "UTF-8"
+    val jar = ZipFile(jarIn)
+    
+    val jarEntries = jar.entries
+
+    for (entry in jar.entries) {
+        zos.addRawArchiveEntry(entry, jar.getRawInputStream(entry))
+    }
+
+    jar.close()
+
+    val src = ZipFile(srcJar)
+
+    for (entry in src.entries) {
+        if (!entryExists(jarEntries, entry)) {
+            zos.addRawArchiveEntry(entry, src.getRawInputStream(entry))
+        }
+    }
+
+    src.close()
+
+    zos.close()
+
+    println("Rezip3 Time: " + (System.currentTimeMillis() - s) + "ms")
+}
+
+fun entryExists(jarEntries: Enumeration<ZipArchiveEntry>, entry: ZipArchiveEntry): Boolean {
+    for (e in jarEntries) {
+        if (e.name == entry.name) {
+            return true
+        }
+    }
+    return false
+}
+