public static String sha1Data(String params,String accessPrivateKey,String signMethod) throws QingException{
		String signParams = "GET\n/iaas/\n"+params;
		byte[] rawHmac = null;
		try {
			SecretKeySpec signingKey = new SecretKeySpec(accessPrivateKey.getBytes(), signMethod);
			Mac mac = Mac.getInstance(signMethod);
			mac.init(signingKey);  
	        rawHmac = mac.doFinal(signParams.getBytes());  
		} catch (NoSuchAlgorithmException nsae) {
			nsae.printStackTrace();
			throw new QingException(nsae.getMessage());
		} catch (InvalidKeyException ike) {
			ike.printStackTrace();
			throw new QingException(ike.getMessage());
		} catch (Exception e) {
			e.printStackTrace();
			throw new QingException(e.getMessage());
		}
		return params+"&signature="+new String(com.qingcloud.util.Base64.encode(rawHmac));
	}