Unpack an Android adb backup using groovy

UnpackAb.groovy

import java.util.zip.*

String backupFile = "c:\\backup.ab";
String outFile = "c:\\backup.tar";

int skip = 0;
System.setProperty("line.separator", (String)(char)10);
File f = new File(backupFile);
FileInputStream fis = new FileInputStream(f);
InputStreamReader sr = new InputStreamReader(fis);
BufferedReader br = new BufferedReader(sr);
String type = br.readLine();
if(type != "ANDROID BACKUP") {
    thorw new Exception("File not an android backup");
}
skip += type.length() + 1;
String version = br.readLine();
skip += version.length() + 1;
String compressed = br.readLine();
skip += compressed.length() + 1;
String encryption = br.readLine();
if(encryption != "none") {
    throw new Exception("Can't handle encryption " + encryption);
}
skip += encryption.length() + 1;
br.close()
fis = new FileInputStream(f);
fis.skip(skip);
InflaterInputStream i = new InflaterInputStream(fis);
FileOutputStream fos = new FileOutputStream(outFile);
try {
    i.eachByte(1024) { buffer, bytesRead ->
        if(bytesRead > 0) {
            fos.write(buffer, 0, bytesRead);
        }
    }
} finally {
    fos.close();
    i.close();
    fis.close();
}