unpacker for MA pack file, and it's easy to generate pack file, possible to customize MA assets.

Unpacker.java

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * unpacker for MA pack file
 */
public final class Unpacker {

	public static void main(String[] args) {
		
		if(args.length >= 1) {
			
			File f = new File(args[0]);
			unpack(f);
		}
	}
	
	private static int readInt(InputStream input) throws IOException {
		
		int ret = 0;
		int i = 3;

		while (i >= 0) {
				
			int k = input.read();
			ret |= k << i * 8;
			i--;
		}
		
		return ret;
	}

	private static byte[] readBytes(InputStream input, int offset, int length)
			throws IOException {

		byte[] bytes = new byte[length];

		input.read(bytes, 0, length);

		return bytes;
	}

	public static boolean unpack(File file) {
		
		log("start unpack: %s", file.getAbsolutePath());
		
		if(!file.exists()) {
			
			error("file dose not exist: %s", file.getAbsolutePath());
			return false;
		}

		BufferedInputStream bi = null;
		int offset = 0;

		try {
			
			bi = new BufferedInputStream(new FileInputStream(file));
			
			int ch = bi.read();

			if(ch != 0x52) {
				
				error("invalid header: %d", ch);
				return false;
			}

			ch = bi.read();

			if(ch != 0x4a) {
				
				error("invalid header: %d", ch);
				return false;
			}

			int total = readInt(bi);
			int pCount = readInt(bi);
			int nth = readInt(bi);

			if(nth == 0) {
				
				log("totalFileSize: %d", total);
				log("packFileCount: %d", pCount);
				log("nthPackFile: %d", nth);
			}
			
			int num = readInt(bi);
			
			offset = 18;//header length
			
			String[] lStr = new String[num];
			int[] lInt = new int[num];
			
			for(int i = 0; i < num; i++) {
				
				int strLength = readInt(bi);
				offset += 4;
				
				byte[] strBytes = readBytes(bi, offset, strLength);
				offset += strLength;
				
				int bytesLength = readInt(bi);
				offset += 4;
				
				lStr[i] = new String(strBytes); 
				lInt[i] = bytesLength;
			}
			
			for(int i = 0; i < num; i ++) {
				
				bi.read();//forward 1byte
				
				int bytesLength = lInt[i];
				
				byte[] bytes = readBytes(bi, offset, bytesLength);
				offset += bytes.length;
				
				String name = lStr[i];
				
				//TODO do something with name and bytes (bytes is encrypted!)
				log(name);
			}
			
			return true;

		} catch (Exception e) {
			
			error("error at offset: %d", offset);
			e.printStackTrace();
			return false;
			
		} finally {
			
			if(bi != null) {
				
				try {
					
					bi.close();
				}
				catch (Exception e2) {
					
					e2.printStackTrace();
				}
			}
		}
	}
	
	private static void log(String format, Object... params) {
		
		System.out.printf(format, params);
		System.out.println();
	}
	
	private static void error(String format, Object... params) {
		
		System.err.printf(format, params);
		System.err.println();
	}
	
}