微信公众号支付流程解读及支付签名验证方法

微信公众号支付大致分为以下几步：

1.获取openID：微信公众号支付一个重要的参数就是openID，此步骤可以查阅相关文档

2.获取支付相关参数：appid：公众账号ID，mch_id：商户号，nonce_str：随机字符串，sign_type：签名类型，out_trade_no：商户订单号，total_fee：标价金额（交易金额默认为人民币交易，接口中参数支付金额单位为【分】，参数值不能带小数），spbill_create_ip：终端IP，notify_url：通知地址，trade_type：交易类型，openid：用户标识，sign：签名

TreeMap paramMap = new TreeMap();
paramMap.put("appid", PaymentConst.WECHAT_APPID);//公众账号ID
paramMap.put("mch_id", PaymentConst.WECHAT_MCHID);//商户号
paramMap.put("nonce_str", Util.getRandomString(30, null));//随机字符串
paramMap.put("sign_type", PaymentConst.WECHAT_SIGNTYPE);//签名类型
//paramMap.put("body", "爱检查医疗套餐支付");//商品描述
paramMap.put("body", "Melical Fee");//商品描述
paramMap.put("out_trade_no", orderMain.getNumber());//商户订单号
//交易金额默认为人民币交易，接口中参数支付金额单位为【分】，参数值不能带小数。
paramMap.put("total_fee", (int)(orderMain.getTotalamount()*100));//标价金额
paramMap.put("spbill_create_ip", Util.getIpAddr(request));//终端IP
paramMap.put("notify_url", weChatNotifyUrl);//通知地址
paramMap.put("trade_type", PaymentConst.WECHAT_TRADETYPE_JSAPI);//交易类型
paramMap.put("openid", openid);//用户标识
paramMap.put("sign",Signature.createSign("UTF-8", paramMap));//签名

3.签名算法：

public static String createSign(String characterEncoding,SortedMap<String,Object> parameters){
StringBuffer sb = new StringBuffer();
Set es = parameters.entrySet();
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=" + PaymentConst.WECHAT_KEY);
System.out.println("签名："+sb.toString());
String sign =MD5.GetMD5Code(sb.toString()).toUpperCase();

return sign;
}

4.请求：

String response = HttpClientUtil.post(PaymentConst.wechatPayUrl,new String( XMLUtils.simpleMapToXml(paramMap).getBytes(), "UTF-8"));

5.XMLUtils.simpleMapToXml 方法：

public static String simpleMapToXml(Map<String, Object> map){
StringBuilder xmlString = new StringBuilder();
xmlString.append("<?xml version='1.0' encoding='UTF-8'?>").append(RT);
xmlString.append("<xml>").append(RT);
for (Map.Entry<String, Object> entry : map.entrySet()){
String key = entry.getKey();
xmlString.append("<" + key + ">" + entry.getValue() + "</" + key + ">").append(RT);
}
xmlString.append("</xml>").append(RT);
return xmlString.toString();
}

6.返回预支付结果，二次签名

  System.out.println("预支付返回结果："+response);
Map<String, String> resultParams = getWechatXmlToMap(response);
if (PaymentConst.WECHAT_STATUSCODE_FAIL.equals(resultParams.get("return_code"))){
throw new MessageException(resultParams.get("return_msg"));
}else{
if (PaymentConst.WECHAT_STATUSCODE_FAIL.equals(resultParams.get("result_code"))){
throw new MessageException(resultParams.get("return_msg"));
}else{
String prepay_id = resultParams.get("prepay_id");

TreeMap paramMap1 = new TreeMap();
paramMap1.put("appId", paramMap.get("appid"));//公众账号ID
String s = String.valueOf(Util.getSecond());
paramMap1.put("timeStamp", s);
paramMap1.put("nonceStr", Util.getRandomString(30, null));
paramMap1.put("package", "prepay_id="+prepay_id);//签名类型
paramMap1.put("signType", paramMap.get("sign_type"));//签名类型
paramMap1.put("sign1",Signature.createSign("UTF-8", paramMap1));//签名
LOGGER.info("最终签名:"+paramMap1.get("sign1"));

//生成前台支付需要的数据
Map<String, Object> map = new HashMap<String, Object>();
map.put("appId", paramMap.get("appid"));
String s1 = String.valueOf(Util.getSecond());
map.put("timeStamp", s1);
map.put("nonceStr", Util.getRandomString(30, null));
map.put("package", "prepay_id="+prepay_id);
map.put("signType", paramMap.get("sign_type"));
map.put("paySign", paramMap1.get("sign1"));
System.out.println("tttttttttttttttttttttttttttttt9999999999999tttttttttttttttttttttttttttttttttttttt");
result.setT(map);
}
}

7./**
* @Title：getWechatXmlToMap
* @Description：微信返回xml结果转为Map
* @param result
* @return
* @throws Exception Map<String,String> 返回类型
*/
private Map<String, String> getWechatXmlToMap(String result) throws Exception{
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
XMLHandler xmlHandler = new XMLHandler();
parser.parse(new ByteArrayInputStream(result.getBytes("UTF-8")), xmlHandler);
return xmlHandler.getParams();
}

8.授权成功回调方法

/**
* @Title：weixinPayBack
* @Description：支付回调(微信支付)
* @param request
* @return String 返回类型
*/
@RequestMapping(value="/weiXinPayNotify")
public String weixinPayBack(HttpServletRequest request){
try {
InputStream inStream = request.getInputStream();
ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inStream.read(buffer)) != -1) {
outSteam.write(buffer, 0, len);
}
outSteam.close();
inStream.close();
String resultStr = new String(outSteam.toByteArray(),"utf-8");
System.out.println("微信支付的回调："+resultStr);
Map<String, String> resultMap = getWechatXmlToMap(resultStr);
String return_code = resultMap.get("return_code");
if("SUCCESS".equals(return_code)){
//检验API返回的数据里面的签名是否合法，避免数据在传输的过程中被第三方篡改
if(!Signature.checkIsSignValidFromResponseString(resultStr)){
throw new MessageException("微信回调参数签名不合法");
}
String result_code = resultMap.get("result_code");
if("SUCCESS".equals(result_code)){
//支付成功的业务逻辑
//通知微信.异步确认成功.必写.不然微信会一直通知后台.八次之后就认为交易失败了.
return "<xml><return_code><![CDATA[SUCCESS]]></return_code><return_msg><![CDATA[OK]]></return_msg></xml>";
}
}
} catch (Exception e) {
LOGGER.error(e.getMessage() ,e);
}
return "<xml><return_code><![CDATA[FAIL]]></return_code><return_msg><![CDATA[ERROR]]></return_msg></xml>";
}