java模拟PHP的pack和unpack类，packunpack

package qghl.intp.util; import java.io.IOException; import java.io.InputStream; public class PackUtil{ /** * 打包字符串 * 类似php中pack在java中的实现 * * @param str * @return */ public static byte[] pack(String str) { int nibbleshift = 4; int position = 0; int len = str.length() / 2 + str.length() % 2; byte[] output = new byte[len]; for (char v : str.toCharArray()) { byte n = (byte) v; if (n >= '0' && n <= '9') { n -= '0'; } else if (n >= 'A' && n <= 'F') { n -= ('A' - 10); } else if (n >= 'a' && n <= 'f') { n -= ('a' - 10); } else { continue; } output[position] |= (n << nibbleshift); if (nibbleshift == 0) { position++; } nibbleshift = (nibbleshift + 4) & 7; } return output; } /** * 16进制的字符解压 类php中unpack * * @param is * @param len * @return * @throws IOException */ public static String unpack(InputStream is, int len) throws IOException { byte[] bytes = new byte[len]; is.read(bytes); return unpack(bytes); } /*** * 16进制的字符解压 类php中unpack * @param bytes * @return */ public static String unpack(byte[] bytes) { StringBuilder stringBuilder = new StringBuilder(""); if (bytes == null || bytes.length <= 0) { return null; } for (int i = 0; i < bytes.length; i++) { int v = bytes[i] & 0xFF; String hv = Integer.toHexString(v); if (hv.length() < 2) { stringBuilder.append(0); } stringBuilder.append(hv); } return stringBuilder.toString(); } }