private static String APPID = "";　　

　　private static String MCHID= "";

　　private static String KEY= "";

　　private static String APPSECRET= "";

　　private static String body= "";

　　private static String notify_url= "";　　　　//回调地址。测试回调必须保证外网能访问到此地址

　  /**
　   * 统一下单接口
     * 微信二维码支付
     * @param params
     * @return
     */
    public String weixin_pay(String out_trade_no,String product_id) {
        JSONObject retJson = new JSONObject();
        try {

            String currTime = PayCommonUtil.getCurrTime();
            String strTime = currTime.substring(8, currTime.length());
            String strRandom = PayCommonUtil.buildRandom(4) + "";
            String nonce_str = strTime + strRandom;　　　　　　//生成随机字符串

            JSONObject requestObj = JSONObject.fromObject(params);
            
            // 正式上线的时候价格根据订单id查询
            String order_price = "1"; // 价格 注意：价格的单位是分

            SortedMap<Object, Object> packageParams = new TreeMap<Object, Object>();
            packageParams.put("appid", APPID);
            packageParams.put("mch_id", MCHID);
            packageParams.put("nonce_str", nonce_str);
            packageParams.put("body", body);
            packageParams.put("out_trade_no", out_trade_no);
            packageParams.put("total_fee", order_price);
            packageParams.put("spbill_create_ip", "用户端ip");
            packageParams.put("notify_url", notify_url);
            packageParams.put("trade_type", "NATIVE");
            packageParams.put("product_id", product_id);
            Calendar nowTime = Calendar.getInstance();
            packageParams.put("time_start", DateFormatUtil.formatDate(
                    nowTime.getTime(), "yyyyMMddHHmmss"));
            nowTime.add(Calendar.MINUTE, requestObj.getInt("expire_time"));
            packageParams.put("time_expire", DateFormatUtil.formatDate(
                    nowTime.getTime(), "yyyyMMddHHmmss"));

            String sign = PayCommonUtil.createSign("UTF-8", packageParams,
                   KEY);
            packageParams.put("sign", sign);　　　　　　　　//加密

            String requestXML = PayCommonUtil.getRequestXml(packageParams);
            logger.info("支付请求：" + requestXML);
            long startTime=System.currentTimeMillis();
            String resXml = HttpRequest.postData(
                    "https://api.mch.weixin.qq.com/pay/unifiedorder",
                    requestXML);
            long endTime=System.currentTimeMillis();
            
            Integer execute_time = (int) ((endTime-startTime)/1000);
            logger.info("支付结果：" + resXml);
            Map map = XMLUtil.doXMLParse(resXml);
            
            JSONObject reportParams = new JSONObject();
            reportParams.put("url", "https://api.mch.weixin.qq.com/pay/unifiedorder");
            reportParams.put("execute_time", execute_time);
            reportParams.put("return_code", map.get("return_code").toString());
            reportParams.put("return_msg", map.get("return_msg").toString());
            reportParams.put("result_code", map.get("result_code").toString());
            if (map.get("err_code") != null) {
                reportParams.put("err_code", map.get("err_code").toString());
                reportParams.put("err_code_des", map.get("err_code_des").toString());
            }
            reportParams.put("out_trade_no", out_trade_no);
            //交易保障
            report(reportParams.toString());
            if (map.get("return_code").toString().equals("SUCCESS") && map.get("result_code").toString().equals("SUCCESS")) {
                String urlCode = (String) map.get("code_url");　　　　　　　　　　//微信二维码短链接
                retJson.put("code", 0);
                retJson.put("message", "下单成功.");
                retJson.put("data", urlCode);
            } else {
                retJson.put("code", 1);
                retJson.put("message", map.get("err_code_des").toString());
                retJson.put("data", "");
            }
            return retJson.toString();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

public class PayCommonUtil {
    
    public static Logger log = LoggerFactory.getLogger(PayCommonUtil.class);
    
    /**
     * 是否签名正确,规则是:按参数名称a-z排序,遇到空值的参数不参加签名。
     * @return boolean
     */  
    public static boolean isTenpaySign(String characterEncoding, SortedMap<Object, Object> 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(!"sign".equals(k) && null != v && !"".equals(v)) {  
                sb.append(k + "=" + v + "&");  
            }  
        }  
          
        sb.append("key=" + API_KEY);  
          
        //算出摘要  
        String mysign = MD5.MD5Encode(sb.toString(), characterEncoding).toLowerCase();  
        String tenpaySign = ((String)packageParams.get("sign")).toLowerCase();  
          
        //System.out.println(tenpaySign + "    " + mysign);  
        return tenpaySign.equals(mysign);  
    }  
 
    /**
     * @author
     * @date 2016-4-22
     * @Description：sign签名
     * @param characterEncoding
     *            编码格式
     * @param parameters
     *            请求参数
     * @return
     */  
    public static String createSign(String characterEncoding, SortedMap<Object, Object> 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 = "";
            try {
                v = (String) entry.getValue();
            } catch (Exception e) {
                // TODO: handle exception
                v = entry.getValue() + "";
            }
             
            if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {  
                sb.append(k + "=" + v + "&");  
            }  
        }  
        sb.append("key=" + API_KEY);  
        String sign = MD5.MD5Encode(sb.toString(), characterEncoding).toUpperCase();  
        return sign;  
    }  
 
    /**
     * @author
     * @date 2016-4-22
     * @Description：将请求参数转换为xml格式的string
     * @param parameters
     *            请求参数
     * @return
     */  
    public static String getRequestXml(SortedMap<Object, Object> parameters) {  
        StringBuffer sb = new StringBuffer();  
        sb.append("<xml>");  
        Set es = parameters.entrySet();  
        Iterator it = es.iterator();  
        while (it.hasNext()) {  
            Map.Entry entry = (Map.Entry) it.next();  
            String k = (String) entry.getKey();
            String v = "";
            try {
                v = (String) entry.getValue();
            } catch (Exception e) {
                // TODO: handle exception
                v = entry.getValue() + "";
            }
             
            if ("attach".equalsIgnoreCase(k) || "body".equalsIgnoreCase(k) || "sign".equalsIgnoreCase(k)) {  
                sb.append("<" + k + ">" + "<![CDATA[" + v + "]]></" + k + ">");  
            } else {  
                sb.append("<" + k + ">" + v + "</" + k + ">");  
            }  
        }  
        sb.append("</xml>");  
        return sb.toString();  
    }  
 
    /**
     * 取出一个指定长度大小的随机正整数.
     *  
     * @param length
     *            int 设定所取出随机数的长度。length小于11
     * @return int 返回生成的随机数。
     */  
    public static int buildRandom(int length) {  
        int num = 1;  
        double random = Math.random();  
        if (random < 0.1) {  
            random = random + 0.1;  
        }  
        for (int i = 0; i < length; i++) {  
            num = num * 10;  
        }  
        return (int) ((random * num));  
    }  
 
    /**
     * 获取当前时间 yyyyMMddHHmmss
     *  
     * @return String
     */  
    public static String getCurrTime() {  
        Date now = new Date();  
        SimpleDateFormat outFormat = new SimpleDateFormat("yyyyMMddHHmmss");  
        String s = outFormat.format(now);  
        return s;  
    }  
    
    
    public static JSONObject httpsRequestToJsonObject(String requestUrl,
            String requestMethod, String outputStr) {
        JSONObject jsonObject = null;
        try {
            StringBuffer buffer = httpsRequest(requestUrl, requestMethod,
                    outputStr);
            jsonObject = JSONObject.fromObject(buffer.toString());
        } catch (ConnectException ce) {
            log.error("连接超时：" + ce.getMessage());
        } catch (Exception e) {
            log.error("https请求异常：" + e.getMessage());
        }
        return jsonObject;
    }

    private static StringBuffer httpsRequest(String requestUrl,
            String requestMethod, String output)
            throws NoSuchAlgorithmException, NoSuchProviderException,
            KeyManagementException, MalformedURLException, IOException,
            ProtocolException, UnsupportedEncodingException {
        URL url = new URL(requestUrl);
        HttpsURLConnection connection = (HttpsURLConnection) url
                .openConnection();
        connection.setDoOutput(true);
        connection.setDoInput(true);
        connection.setUseCaches(false);
        connection.setRequestMethod(requestMethod);
        if (null != output) {
            OutputStream outputStream = connection.getOutputStream();
            outputStream.write(output.getBytes("UTF-8"));
            outputStream.close();
        }
        // 从输入流读取返回内容
        InputStream inputStream = connection.getInputStream();
        InputStreamReader inputStreamReader = new InputStreamReader(
                inputStream, "utf-8");
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        String str = null;
        StringBuffer buffer = new StringBuffer();
        while ((str = bufferedReader.readLine()) != null) {
            buffer.append(str);
        }
        bufferedReader.close();
        inputStreamReader.close();
        inputStream.close();
        inputStream = null;
        connection.disconnect();
        return buffer;
    }
}