android端微信支付V3版本地签名统一下单详解

满满的都是坑，因为服务器偷懒让客服端写统一下单，服务器只给了通知的url。微信的支付demo并没有统一下单的代码。

读此文前先阅读： https://pay.weixin.qq.com/wiki/doc/api/app/app.PHP?chapter=9_1

一步步的来  先根据统一下单的参数介绍工具：

1. 获取到当前的ip：

<span style="font-size:14px;">public String getLocalIpAddress() { 
    try { 
      for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements(); ) { 
        NetworkInterface intf = en.nextElement(); 
        for (Enumeration<InetAddress> enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements(); ) { 
          InetAddress inetAddress = enumIpAddr.nextElement(); 
          if (!inetAddress.isLoopbackAddress()) { 
            return inetAddress.getHostAddress().toString(); 
          } 
        } 
      } 
    } catch (SocketException ex) { 
    } 
    return null; 
  } 
  private String getWifiIp() { 
    //获取wifi服务 
    WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE); 
    //判断wifi是否开启 
    if (!wifiManager.isWifiEnabled()) { 
      wifiManager.setWifiEnabled(true); 
    } 
    WifiInfo wifiInfo = wifiManager.getConnectionInfo(); 
    int ipAddress = wifiInfo.getIpAddress(); 
    String ip = intToIp(ipAddress); 
    return ip; 
  } 
  private String intToIp(int i) { 
    return (i & 0xFF) + "." + 
        ((i >> 8) & 0xFF) + "." + 
        ((i >> 16) & 0xFF) + "." + 
        (i >> 24 & 0xFF); 
  } 
</span> 

2.随机订单号生成 test 你们可根据自己生成随机数：

<span style="font-size:14px;">private String genOutTradNo() { 
    Random random = new Random(); 
    return MD5.getMessageDigest(String.valueOf(random.nextInt(10000)).getBytes()); 
  }</span> 

3.签名工具：

<span style="font-size:14px;">private String genAppSign(List<NameValuePair> params) { 
    StringBuilder sb = new StringBuilder(); 
    for (int i = 0; i < params.size(); i++) { 
      sb.append(params.get(i).getName()); 
      sb.append('='); 
      sb.append(params.get(i).getValue()); 
      sb.append('&'); 
    } 
    sb.append("key="); 
    sb.append(Constants.API_KEY); 
    this.sb.append("sign str\n"+sb.toString()+"\n\n"); 
    String appSign = MD5.getMessageDigest(sb.toString().getBytes()); 
    Log.e("orion",appSign); 
    return appSign; 
  }</span> 

差不多了  现在我们需要生成传递的参数   参数要求是xml 格式的：

<span style="font-size:14px;">private String genProductArgs() { 
    StringBuffer xml = new StringBuffer(); 
    String ip = getWifiIp(); 
    if (ip == "" && ip == "") { 
      ip = getLocalIpAddress(); 
    } 
    try { 
      String nonceStr = genNonceStr(); 
      xml.append("</xml>"); 
      List<NameValuePair> packageParams = new LinkedList<NameValuePair>(); 
      packageParams.add(new BasicNameValuePair("appid", Constants.APP_ID)); 
      packageParams.add(new BasicNameValuePair("body", "APP pay test")); 
      packageParams.add(new BasicNameValuePair("mch_id", Constants.MCH_ID)); 
      packageParams.add(new BasicNameValuePair("nonce_str", nonceStr)); 
      packageParams.add(new BasicNameValuePair("notify_url",ConfigUtil.NOTIFY_URL)); 
      packageParams.add(new BasicNameValuePair("out_trade_no",genOutTradNo())); 
      packageParams.add(new BasicNameValuePair("spbill_create_ip",ip)); 
      packageParams.add(new BasicNameValuePair("total_fee", "1")); 
      packageParams.add(new BasicNameValuePair("trade_type", "APP")); 
      String sign = genPackageSign(packageParams); 
      packageParams.add(new BasicNameValuePair("sign", sign)); 
      String xmlstring =toXml(packageParams); 
      return xmlstring; 
    } catch (Exception e) { 
      Log.e("TAG", "fail, ex = " + e.getMessage()); 
      return null; 
    } 
  }</span> 

其中  toxml：

<span style="font-size:14px;">private String toXml(List<NameValuePair> params) { 
    StringBuilder sb = new StringBuilder(); 
    sb.append("<xml>"); 
    for (int i = 0; i < params.size(); i++) { 
      sb.append("<"+params.get(i).getName()+">"); 
      sb.append(params.get(i).getValue()); 
      sb.append("</"+params.get(i).getName()+">"); 
    } 
    sb.append("</xml>"); 
    Log.e("orion",sb.toString()); 
    return sb.toString(); 
  }</span> 

得到传递的参数，根据文档指示，我们需要用post去吊连接URL地址：Https://api.mch.weixin.qq.com/pay/unifiedorder：

<span style="font-size:14px;">  private class GetPrepayIdTask extends AsyncTask<Void, Void, Map<String,String>> { 
    private ProgressDialog dialog; 
    @Override 
    protected void onPreExecute() { 
      dialog = ProgressDialog.show(PayActivity.this, getString(R.string.app_tip), getString(R.string.getting_prepayid)); 
    } 
    @Override 
    protected void onPostExecute(Map<String,String> result) { 
      if (dialog != null) { 
        dialog.dismiss(); 
      } 
      sb.append("prepay_id\n"+result.get("prepay_id")+"\n\n"); 
      resultunifiedorder=result; 
    } 
    @Override 
    protected void onCancelled() { 
      super.onCancelled(); 
    } 
    @Override 
    protected Map<String,String> doInBackground(Void... params) { 
      String url = String.fORMat("https://api.mch.weixin.qq.com/pay/unifiedorder"); 
      String entity = genProductArgs(); 
      Log.e("orion",entity); 
      byte[] buf = Util.httpPost(url, entity); 
      String content = new String(buf); 
      Log.e("orion", content); 
      Map<String,String> xml=decodeXml(content); 
      return xml; 
    } 
  }</span> 

 其中decodexml就是：

 <span style="font-size:14px;">public Map<String,String> decodeXml(String content) { 
    try { 
      Map<String, String> xml = new HashMap<String, String>(); 
      XmlPullParser parser = Xml.newPullParser(); 
      parser.setInput(new StringReader(content)); 
      int event = parser.getEventType(); 
      while (event != XmlPullParser.END_DOCUMENT) { 
        String nodeName=parser.getName(); 
        switch (event) { 
          case XmlPullParser.START_DOCUMENT: 
            break; 
          case XmlPullParser.START_TAG: 
            if("xml".equals(nodeName)==false){ 
              //实例化student对象 
              xml.put(nodeName,parser.nextText()); 
            } 
            break; 
          case XmlPullParser.END_TAG: 
            break; 
        } 
        event = parser.next(); 
      } 
      return xml; 
    } catch (Exception e) { 
      Log.e("orion",e.toString()); 
    } 
    return null; 
  }</span> 

 下单完成，第二部就是给微信支付传递调起微信支付的参数（具体参数看文档说明）：

 <span style="font-size:14px;">private void genPayReq() { 
    req.appId = Constants.APP_ID; 
    req.partnerId = Constants.MCH_ID; 
    req.prepayId = resultunifiedorder.get("prepay_id"); 
    req.packageValue = "prepay_id="+resultunifiedorder.get("prepay_id"); 
    req.nonceStr = genNonceStr(); 
    req.timeStamp = String.valueOf(genTimeStamp()); 
    List<NameValuePair> signParams = new LinkedList<NameValuePair>(); 
    signParams.add(new BasicNameValuePair("appid", req.appId)); 
    signParams.add(new BasicNameValuePair("noncestr", req.nonceStr)); 
    signParams.add(new BasicNameValuePair("package", req.packageValue)); 
    signParams.add(new BasicNameValuePair("partnerid", req.partnerId)); 
    signParams.add(new BasicNameValuePair("prepayid", req.prepayId)); 
    signParams.add(new BasicNameValuePair("timestamp", req.timeStamp)); 
    req.sign = genAppSign(signParams); 
    sb.append("sign\n"+req.sign+"\n\n"); 
    Log.e("orion", signParams.toString()); 
  }</span> 

 第三部，调微信支付：

 <span style="font-size:14px;">private void sendPayReq() { 
    msgApi.reGISterApp(Constants.APP_ID); 
    msgApi.sendReq(req); 
  }</span> 

 其中：

 <span style="font-size:14px;">Constants.APP_ID</span> 

是appid 在开发者平台获取

<span style="font-size:14px;">    req.partnerId = Constants.MCH_ID;</span> 

商户id

<span style="font-size:14px;">ConfigUtil.NOTIFY_URL</span> 

支付后的回调通知地址。

签名两次，然后用的api——key是商户平台api安全里面自定义的。

对了 还有个获取时间工具

<span style="font-size:14px;">private long genTimeStamp() { 
    return System.currentTimeMillis() / 1000; 
  }</span> 

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