java模拟PHP的pack和unpack类

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();
}
}

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