微信支付 第二次签名遇到的坑

微信支付第二次加签参数

appid  partnerid prepayid noncestr timestamp package

package为固定值 Sign=WXPay
timestamp 为十位时间戳
其他参数为统一下单时返回的参数

这里使用的事MD5加密 需要与统一下单时的参数一致

SortedMap sortedMap = new TreeMap<>();
​​​​​​​sortedMap.put("appid",(String)map.get("appid"));
sortedMap.put("partnerid",(String)map.get("mch_id"));
sortedMap.put("prepayid",(String)map.get("prepay_id"));
sortedMap.put("noncestr",(String)map.get("nonce_str"));
sortedMap.put("timestamp",time.toString());
sortedMap.put("package","Sign=WXPay");
String sign = PayCommonUtil.createSign("UTF-8", sortedMap, key);

PayCommonUtil类

	public static String createSign(String characterEncoding, SortedMap 
     packageParams, String API_KEY) {
        StringBuffer sb = new StringBuffer();
        Set es = packageParams.entrySet();
        Iterator it = es.iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            String k = (String) entry.getKey();
            String v = (String) entry.getValue();
            if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
                sb.append(k + "=" + v + "&");
            }
        }
        sb.append("key=" + API_KEY);
        String sign = MD5Util.MD5Encode(sb.toString(), characterEncoding).toUpperCase();

        return sign;
    }

MD5Util 加密工具类

public class 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" };
}