Java 16进制字符串与2进制字符串相互转换

public static String hexString2binaryString(String hexString) {
if (hexString == null || hexString.length() % 2 != 0)
return null;
String bString = "", tmp;
for (int i = 0; i < hexString.length(); i++) {
tmp = "0000" + Integer.toBinaryString(Integer.parseInt(hexString.substring(i, i + 1), 16));
bString += tmp.substring(tmp.length() - 4);
}
return bString;
}
//------------------------------------------------------
public static String binaryString2hexString(String bString) {
if (bString == null || bString.equals("") || bString.length() % 8 != 0)
return null;
StringBuffer tmp=new StringBuffer();
int iTmp = 0;
for (int i = 0; i < bString.length(); i += 4) {
iTmp = 0;
for (int j = 0; j < 4; j++) {
iTmp += Integer.parseInt(bString.substring(i + j, i + j + 1)) << (4 - j - 1);
}
tmp.append(Integer.toHexString(iTmp));
}
return tmp.toString();
}