如何在zip文件中使用相对路径？（很急，解决马上给分，在线等候）

Question

压缩目录的代码：
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;public class FileZip
{
    static final char SEPARATOR = File.separatorChar;
    private int preffixLen = 0;    public void compress(OutputStream out, File file) throws IOException
    {
        preffixLen = file.getParentFile().getAbsolutePath().length() + 1;
        ZipOutputStream zos = new ZipOutputStream(out);
        addFile(zos, file);
        zos.close();
    }    private void addFile(ZipOutputStream zos, File file) throws IOException
    {
        String entryName = entryName(file);
        if (entryName.equals("") || entryName.equals("."))
            return;        System.out.println("adding " + entryName);
        ZipEntry entry = new ZipEntry(entryName);
        entry.setTime(file.lastModified());
        boolean isDirectory = file.isDirectory();
        if (isDirectory)
        {
            entry.setMethod(0);
            entry.setSize(0L);
            entry.setCrc(0L);
        }
        else
            entry.setSize(file.length());        zos.putNextEntry(entry);
        if (isDirectory)
        {
            File[] files = file.listFiles();
            for(int i=0; i<files.length; i++)
                addFile(zos, files[i]);
        }
        else
        {
            byte buf[] = new byte[1024];
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
            int bytes;
            while ((bytes = bis.read(buf, 0, buf.length)) != -1)
                zos.write(buf, 0, bytes);
            bis.close();
        }
        zos.closeEntry();
    }    private String entryName(File file)
    {
        String entryName = file.getPath();
        if (file.isDirectory())
            entryName = entryName.endsWith(File.separator) ? entryName : entryName + File.separator;
        entryName = entryName.replace(File.separatorChar, '/').substring(preffixLen);
        return entryName;
    }    public static void main(String args[])
    {
        try
        {
            FileOutputStream fos = new FileOutputStream("test.zip"); //压缩到test.zip文件
            FileZip zip = new FileZip();
            zip.compress(new BufferedOutputStream(fos), new File("c:\\downloads\\ggg")); //压缩目录c:\\downloads\\ggg
            fos.close();
        }
        catch (Throwable e)
        {
            e.printStackTrace();
        }
    }
}