Althought this thread is rather old, I used the script to concatenate my CSS files. I recognized that it does not cut out comments nor relative URLs from folders below the root folder work correctly, so I fixed them. As I did not found this tool as an addon within the repository, I will just drop the code here, maybe someone will find it useful 
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class ConcatenateCss {
private static final String SEPARATOR = "----------------------------------------------------------------------";
private static final Pattern URL_PATTERN = Pattern.compile("url\\(['\"]
?(.*?)['\"]
?\\)");
private static final Pattern COMMENT_START = Pattern.compile("/\\*");
private static final Pattern COMMENT_END = Pattern.compile("\\*/");
private static File cssRootDir;
private static File cssRootFile;
private static File cssRootFileAll;
private static URI cssRootUri;
private static int fileCount;
private static int lineCount;
public static void main(final String[] args) throws IOException {
if (args.length != 2) {
System.err.println("Usage: java ConcatenateCss [path to root css file]
[path to target css file]
");
return;
}
final String fileName = args[0]
;
cssRootFile = new File(fileName);
cssRootDir = cssRootFile.getParentFile();
cssRootFileAll = new File(args[1]
);
cssRootUri = cssRootDir.toURI();
System.out.println("CSS root file is: " + cssRootFile);
System.out.println("Concatenated CSS: " + cssRootFileAll);
System.out.println("---");
final StringBuilder cssContent = new StringBuilder();
cssContent.append("/* CSS CONCATENATED FROM SUBDIRECTORIES */\n");
concatenate(cssRootFile, cssContent);
++fileCount;
final BufferedWriter out = new BufferedWriter(new FileWriter(
cssRootFileAll));
out.write(cssContent.toString());
out.close();
System.out.println("---");
System.out.println("Successfully concatenated " + fileCount
+ " files (" + lineCount + " lines)");
}
private static boolean concatenate(final File cssFile,
final StringBuilder cssContent) throws IOException {
if (!cssFile.isFile()) {
System.out.println("Ignored file: " + cssFile
+ " (missing or not a file)");
return false;
}
cssContent.append("/* " + SEPARATOR + " "
+ cssFile.getName().toUpperCase() + " */\n");
++lineCount;
final DataInputStream in = new DataInputStream(new FileInputStream(
cssFile));
final BufferedReader br = new BufferedReader(new InputStreamReader(in));
String line;
boolean commentActive = false;
while ((line = br.readLine()) != null) {
// Remove comments:
if (!commentActive) {
Matcher commentStartMatcher = COMMENT_START.matcher(line);
if (commentStartMatcher.find()) {
// Filter for Comments within one line:
String restLine = line.substring(commentStartMatcher.end(0));
Matcher commentEndMatcher = COMMENT_END.matcher(restLine);
if (commentEndMatcher.find()) {
line = line.substring(0, commentStartMatcher.start(0)) + restLine.substring(commentEndMatcher.end(0));
} else {
commentActive = true;
line = line.substring(0, commentStartMatcher.start(0));
}
}
} else {
Matcher commentEndMatcher = COMMENT_END.matcher(line);
if (commentEndMatcher.find()) {
commentActive = false;
line = line.substring(commentEndMatcher.end(0));
} else {
continue;
}
}
if (line == null || line.equals("")) {
continue;
}
if (line.startsWith("@import")) {
final Matcher urlMatcher = URL_PATTERN.matcher(line);
if (urlMatcher.find()) {
final String url = urlMatcher.group(1);
File importFile = new File(url);
if (!importFile.isAbsolute()) {
importFile = new File(cssFile.getParentFile(), url);
}
if (!concatenate(importFile, cssContent)) {
cssContent.append(line).append("\n");
++lineCount;
} else {
++fileCount;
System.out.println("Concatenated: " + importFile);
}
} else {
cssContent.append(line).append("\n");
++lineCount;
System.out
.println("Warning: Could not find url(...) pattern");
}
continue;
}
final Matcher urlMatcher = URL_PATTERN.matcher(line);
if (urlMatcher.find()) {
final String url = urlMatcher.group(1);
File imageFile = new File(url);
if (!imageFile.isAbsolute()) {
imageFile = new File(cssFile.getParentFile(), url);
String newUrl = cssRootUri.relativize(imageFile.toURI()).getPath();
newUrl = newUrl.replaceAll(cssRootUri.getPath(), "");
line = line.replaceAll(url, newUrl);
}
}
cssContent.append(line).append("\n");
++lineCount;
}
in.close();
return true;
}
}
Cheers,
Martin