public static String getSha1(String str) {

if (null == str || 0 == str.length()) {

returnnull;

}

char[] hexDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

try {

MessageDigest mdTemp = MessageDigest.getInstance("SHA1");

mdTemp.update(str.getBytes("UTF-8"));

byte[] md = mdTemp.digest();

int j = md.length;

char[] buf = new char[j * 2];

int k = 0;

for (int i = 0; i < j; i++) {

byte byte0 = md[i];

buf[k++] = hexDigits[byte0 >>> 4 & 0xf];

buf[k++] = hexDigits[byte0 & 0xf];

}

return new String(buf);

} catch (Exception e) {

returnnull;

}

}