sha1加密

public static String getSha1(String str){
		if (null == str || 0 == str.length()){
			return null;
		}
		
		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 (NoSuchAlgorithmException e) {
				e.printStackTrace();
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		return str;
	}