private String genProductArgs() { 
 StringBuffer xml = new StringBuffer(); 
 
 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", "weixin")); 
 packageParams 
  .add(new BasicNameValuePair("mch_id", Constants.MCH_ID)); 
 packageParams.add(new BasicNameValuePair("nonce_str", nonceStr)); 
 packageParams.add(new BasicNameValuePair("notify_url", 
  "http://121.40.35.3/test")); 
 packageParams.add(new BasicNameValuePair("out_trade_no", 
  genOutTradNo())); 
 packageParams.add(new BasicNameValuePair("spbill_create_ip", 
  "127.0.0.1")); 
 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, "genProductArgs fail, ex = " + e.getMessage()); 
 return null; 
 } 
 
 } 

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); 

private void genPayReq() { 
 
 req.appId = Constants.APP_ID; 
 req.partnerId = Constants.MCH_ID; 
 req.prepayId = resultunifiedorder.get("prepay_id"); 
 req.packageValue = "Sign=WXPay"; 
 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"); 
 
 show.setText(sb.toString()); 
 
 Log.e("orion", signParams.toString()); 
 
 } 

private String genNonceStr() { 
 Random random = new Random(); 
 return MD5.getMessageDigest(String.valueOf(random.nextInt(10000)) 
 .getBytes()); 
 } 

private long genTimeStamp() { 
 return System.currentTimeMillis() / 1000; 
 } 

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()) 
 .toUpperCase(); 
 Log.e("orion", appSign); 
 return appSign; 
 } 

<activity 
 android:name=".act.PayActivity" 
 android:exported="true" 
 android:launchMode="singleTop" > 
 <intent-filter> 
 <action android:name="android.intent.action.VIEW" /> 
 
 <category android:name="android.intent.category.DEFAULT" /> 
 
 <data android:scheme="wxf2f565574a968187" /> 
 </intent-filter> 
 </activity> 

private void sendPayReq() { 
 
 msgApi.registerApp(Constants.APP_ID); 
 msgApi.sendReq(req); 
 } 

public void onResp(BaseResp resp) { 
 Log.d(TAG, "onPayFinish, errCode = " + resp.errCode); 
 
 if (resp.getType() == ConstantsAPI.COMMAND_PAY_BY_WX) { 
 AlertDialog.Builder builder = new AlertDialog.Builder(this); 
 builder.setTitle(R.string.app_tip); 
 builder.setMessage(getString(R.string.pay_result_callback_msg, 
  resp.errStr + ";code=" + String.valueOf(resp.errCode))); 
 builder.show(); 
 } 
 }