微信签名生成算法

工作笔记：

MD5Util：

private static String byteArrayToHexString(byte b[]) {
		StringBuffer resultSb = new StringBuffer();
		for (int i = 0; i < b.length; i++)
			resultSb.append(byteToHexString(b[i]));

		return resultSb.toString();
	}

	private static String byteToHexString(byte b) {
		int n = b;
		if (n < 0)
			n += 256;
		int d1 = n / 16;
		int d2 = n % 16;
		return hexDigits[d1] + hexDigits[d2];
	}

	public static String MD5Encode(String origin, String charsetname) {
		String resultString = null;
		try {
			resultString = new String(origin);
			MessageDigest md = MessageDigest.getInstance("MD5");
			if (charsetname == null || "".equals(charsetname))
				resultString = byteArrayToHexString(md.digest(resultString
						.getBytes()));
			else
				resultString = byteArrayToHexString(md.digest(resultString
						.getBytes(charsetname)));
		} catch (Exception exception) {
		}
		return resultString;
	}

	private static final String hexDigits[] = { "0", "1", "2", "3", "4", "5",
		"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
sign 生成： 	

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		System.out.println(">>>模拟微信支付<<<");
		System.out.println("==========华丽的分隔符==========");
		//微信api提供的参数
		String appid = "wxd930ea5d5a258f4f";
		String mch_id = "10000100";
		String device_info = "1000";
		String body = "test";
		String nonce_str = "ibuaiVcKdpRxkhJA";
		
		SortedMap<Object,Object> parameters = new TreeMap<Object,Object>();
		parameters.put("appid", appid);
		parameters.put("mch_id", mch_id);
		parameters.put("device_info", device_info);
		parameters.put("body", body);
		parameters.put("nonce_str", nonce_str);
		
		String characterEncoding = "UTF-8";
		String weixinApiSign = "9A0A8659F005D6984697E2CA0A9CF3B7";
		System.out.println("微信的签名是：" + weixinApiSign);
		String mySign = createSign(characterEncoding,parameters);
		System.out.println("我     的签名是："+mySign);
		
		if(weixinApiSign.equals(mySign)){
			System.out.println("恭喜你成功了~");
		}else{
			System.out.println("注定了你是个失败者~");
		}
		
		String userAgent = "Mozilla/5.0(iphone;CPU iphone OS 5_1_1 like Mac OS X) AppleWebKit/534.46(KHTML,like Geocko) Mobile/9B206 MicroMessenger/5.0";
		
		char agent = userAgent.charAt(userAgent.indexOf("MicroMessenger")+15);
		
		System.out.println("微信的版本号："+new String(new char[]{agent}));
	}

	/**
	 * 微信支付签名算法sign
	 * @param characterEncoding
	 * @param parameters
	 * @return
	 */
	@SuppressWarnings("unchecked")
	public static String createSign(String characterEncoding,SortedMap<Object,Object> parameters){
		StringBuffer sb = new StringBuffer();
		Set es = parameters.entrySet();//所有参与传参的参数按照accsii排序（升序）
		Iterator it = es.iterator();
		while(it.hasNext()) {
			Map.Entry entry = (Map.Entry)it.next();
			String k = (String)entry.getKey();
			Object v = entry.getValue();
			if(null != v && !"".equals(v) 
					&& !"sign".equals(k) && !"key".equals(k)) {
				sb.append(k + "=" + v + "&");
			}
		}
		sb.append("key=" + Key);
		String sign = MD5Util.MD5Encode(sb.toString(), characterEncoding).toUpperCase();
		return sign;
	}