code: public static List<File> unzip(File zip, File toDir) throws IOException {
  		ZipFile zf = null;
  		List<File> files = null;
  		try {
  			zf = new ZipFile(zip);
  			files = new ArrayList<File>();
  			Enumeration<?> entries = zf.entries();
  			while (entries.hasMoreElements()) {
  				ZipEntry entry = (ZipEntry) entries.nextElement();
  				if (entry.isDirectory()) {
  					new File(toDir, entry.getName()).mkdirs();
  					continue;
  				}
  
  				InputStream input = null;
  				OutputStream output = null;
  				try {
  					File f = new File(toDir, entry.getName());
  					input = zf.getInputStream(entry);
  					output = new FileOutputStream(f);
  					copy(input, output);
  					files.add(f);
  				} finally {
  					closeQuietly(output);
  					closeQuietly(input);
  				}
  			}
  		} finally {
  			if (zf != null) {
  				zf.close();
  			}
  		}
  		return files;
  	}
docs: 解压zip文件到指定的目录。
  
  @param zip 需要解压的zip文件
  @param toDir 需要解压到的目录
  @return 解压后的文件列表（不包含文件夹）