/**
* 微信支付签名算法sign
* @param characterEncoding
* @param parameters
* @return
*/
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=" + WEIXIN_KEY);
System.out.println("签名字符串:"+sb.toString());
System.out.println("签名MD5未变大写：" + MD5Util.MD5Encode(sb.toString(), characterEncoding));
String sign = MD5Util.MD5Encode(sb.toString(), characterEncoding).toUpperCase();
return sign;
}