public String weixin_pay(Integer orderId) throws Exception {

        TPredepositOrder predepositOrder=predepositOrderService.getPredepositOrderInfoById(orderId);//根据订单号获取订单信息

        // 账号信息

        String appid = Constants.appid;           // appid  开发者id 登录公众号》开发》基本配置 AppID(应用ID)后面就是

        String mch_id =Constants.WEIXIN_MCH_ID;   // 商业号  不知道的问你老板要

        String key = Constants.WEIXIN_PAY_KEY;    // key    登录微信商户号后，找到账户设置 -> 密码安全 -> API安全 -> API密钥；不会的这个有个地址点开看 http://www.2cto.com/weixin/201506/412421.html

     
        //根据时间生成随机字符串

        String currTime = PayCommonUtil.getCurrTime();

        String strTime = currTime.substring(8, currTime.length());

        String strRandom = PayCommonUtil.buildRandom(4) + "";

        String nonce_str = strTime + strRandom;  

        //价格处理

        Double price=predepositOrder.getPreDeposit();

        int total_fee=(int) (price*100);

        String order_price =total_fee+"";           // 价格   注意：价格的单位是分  

        String body = "天天酷跑-游戏充值";            // 商品名称 格式必须是 公司名称-商品名称

        String out_trade_no = orderId.toString();   // 订单号  

        // 获取发起电脑 ip

        String ip=InetAddress.getLocalHost().toString();

        ip=ip.substring(ip.lastIndexOf('/')+1,ip.length());

        System.out.println("本机的IP = " +ip);

        String spbill_create_ip =ip;

        // 回调接口回调地址

        String notify_url = Constants.NOTIFY_URL;

        String trade_type = "NATIVE";  //支付类型 网页扫码支付就用这个 不解释

        SortedMap<Object,Object> packageParams = new TreeMap<Object,Object>();

        packageParams.put("appid", appid);

        packageParams.put("body", body);

        packageParams.put("mch_id", mch_id);

        packageParams.put("nonce_str",nonce_str);

        packageParams.put("notify_url", notify_url);

        packageParams.put("out_trade_no",out_trade_no);

        packageParams.put("spbill_create_ip", spbill_create_ip);

        packageParams.put("total_fee", order_price);

        packageParams.put("trade_type", trade_type);

        String sign = PayCommonUtil.createSign("UTF-8",packageParams,key);

        packageParams.put("sign",sign);

        String requestXML = PayCommonUtil.getRequestXml(packageParams);

        System.out.println(requestXML);

        String resXml = HttpUtil.postData("https://api.mch.weixin.qq.com/pay/unifiedorder",requestXML);//这个是微信返回url的接口地址

        System.out.println("返回的xml信息"+resXml);

        Map map = XMLUtil.doXMLParse(resXml);

        String urlCode = (String) map.get("code_url");

        System.out.println("支付地址"+urlCode);

        return urlCode;

} 

<div style="margin-top: 10px;width:500px;height:500px;" id="output"></div>

<script type="text/javascript" src="weixin/js/jquery.qrcode-0.12.0.min.js"></script><--!引入生成二维码的js--->

<script type="text/javascript">

      var url = '${urlCode}';

      jQuery('#output').qrcode({render: "table",width:500,height:500,correctLevel:0,text:url});

      window.setInterval("selectInfo()",10000);

      function selectInfo(){

        //用定时函数不停的获取该订单编号的状态 如果是已付款 弹出支付成功 跳转到相应的页面

      }

   </script>

@RequestMapping("weixin_notify")

    public void weixin_notify(HttpServletRequest request,HttpServletResponse response) throws Exception{

        //读取参数

        InputStream inputStream ;

        StringBuffer sb = new StringBuffer();

        inputStream = request.getInputStream();

        String s ;

        BufferedReader in = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));

        while ((s = in.readLine()) != null){

            sb.append(s);

        }

        in.close();

        inputStream.close();  

        //解析xml成map

        Map<String, String> m = new HashMap<String, String>();

        m = XMLUtil.doXMLParse(sb.toString());  

        //过滤空 设置 TreeMap

        SortedMap<Object,Object> packageParams = new TreeMap<Object,Object>();

        Iterator it = m.keySet().iterator();

        while (it.hasNext()) {

            String parameter = (String) it.next();

            String parameterValue = m.get(parameter);  

            String v = "";

            if(null != parameterValue) {

                v = parameterValue.trim();

            }

            packageParams.put(parameter, v);

        }  

        // 账号信息

        String key = Constants.WEIXIN_PAY_KEY; // key  

        logger.info(packageParams);

        //判断签名是否正确

        if(PayCommonUtil.isTenpaySign("UTF-8", packageParams,key)) {

            //------------------------------

            //处理业务开始

            //------------------------------

            String resXml = "";

            if("SUCCESS".equals((String)packageParams.get("result_code"))){

                // 这里是支付成功

                //////////执行自己的业务逻辑////////////////  

                //获取订单号

                String out_trade_no = (String)packageParams.get("out_trade_no");

                //调用根据订单号更改订单状态的方法

//////////执行自己的业务逻辑////////////////  

                logger.info("支付成功");

                //通知微信.异步确认成功.必写.不然会一直通知后台.八次之后就认为交易失败了.

                resXml = "<xml>" + "<return_code><![CDATA[SUCCESS]]></return_code>"

                        + "<return_msg><![CDATA[OK]]></return_msg>" + "</xml> ";  

            } else {

                logger.info("支付失败,错误信息：" + packageParams.get("err_code"));

                resXml = "<xml>" + "<return_code><![CDATA[FAIL]]></return_code>"

                        + "<return_msg><![CDATA[报文为空]]></return_msg>" + "</xml> ";

            }

            //------------------------------

            //处理业务完毕

            //------------------------------

            BufferedOutputStream out = new BufferedOutputStream(  response.getOutputStream());

            out.write(resXml.getBytes());

            out.flush();

            out.close();

        } else{

            logger.info("通知签名验证失败");

        }  

    }  

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.net.URL;

import java.net.URLConnection;

//这个工具类是 根据url

public class HttpUtil {  

    private final static int CONNECT_TIMEOUT = 5000; // in milliseconds

    private final static String DEFAULT_ENCODING = "UTF-8";  

    public static String postData(String urlStr, String data){

        return postData(urlStr, data, null);

    }  

    /****

     * 功能描述 根据url    请求接口  返回String数据

     * @param urlStr    接口地址

     * @param data

     * @param contentType

     * @return

     */

    public static String postData(String urlStr, String data, String contentType){

        BufferedReader reader = null;

        try {

            URL url = new URL(urlStr);

            URLConnection conn = url.openConnection();

            conn.setDoOutput(true);

            conn.setConnectTimeout(CONNECT_TIMEOUT);

            conn.setReadTimeout(CONNECT_TIMEOUT);

            if(contentType != null)

                conn.setRequestProperty("content-type", contentType);

            OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream(), DEFAULT_ENCODING);

            if(data == null)

                data = "";

            writer.write(data);

            writer.flush();

            writer.close();    

            reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), DEFAULT_ENCODING));

            StringBuilder sb = new StringBuilder();

            String line = null;

            while ((line = reader.readLine()) != null) {

                sb.append(line);

                sb.append("\r\n");

            }

            return sb.toString();

        } catch (IOException e) {

            e.getMessage();

        } finally {

            try {

                if (reader != null)

                    reader.close();

            } catch (IOException e) {

            }

        }

        return null;

    }

}  

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.Iterator;

import java.util.Map;

import java.util.Set;

import java.util.SortedMap;

import com.ruanyun.common.utils.MD5;

import com.ruanyun.common.utils.MD5Util;

public class PayCommonUtil {  

    /**

     * 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 = MD5Util.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();  //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();

            String v = (String) entry.getValue();

            if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {

                sb.append(k + "=" + v + "&");

            }

        }

        sb.append("key=" + API_KEY);

        System.out.println("StringQ:参数排列顺序"+sb.toString());

        String sign = MD5.MD5Encode(sb.toString(),characterEncoding).toUpperCase();  //sign必须是大写

        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 = (String) 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;

    }  

}

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import org.jdom.Document;

import org.jdom.Element;

import org.jdom.JDOMException;

import org.jdom.input.SAXBuilder;

public class XMLUtil {

     /**

     * 解析xml,返回第一级元素键值对。如果第一级元素有子节点，则此节点的值是子节点的xml数据。

     * @param strxml

     * @return

     * @throws JDOMException

     * @throws IOException

     */

    public static Map doXMLParse(String strxml) throws JDOMException, IOException {

        strxml = strxml.replaceFirst("encoding=\".*\"", "encoding=\"UTF-8\"");  

        if(null == strxml || "".equals(strxml)) {

            return null;

        }  

        Map m = new HashMap();  

        InputStream in = new ByteArrayInputStream(strxml.getBytes("UTF-8"));

        SAXBuilder builder = new SAXBuilder();

        Document doc = builder.build(in);

        Element root = doc.getRootElement();

        List list = root.getChildren();

        Iterator it = list.iterator();

        while(it.hasNext()) {

            Element e = (Element) it.next();

            String k = e.getName();

            String v = "";

            List children = e.getChildren();

            if(children.isEmpty()) {

                v = e.getTextNormalize();

            } else {

                v = XMLUtil.getChildrenText(children);

            }  

            m.put(k, v);

        }  

        //关闭流

        in.close();  

        return m;

    }  

    /**

     * 获取子结点的xml

     * @param children

     * @return String

     */

    public static String getChildrenText(List children) {

        StringBuffer sb = new StringBuffer();

        if(!children.isEmpty()) {

            Iterator it = children.iterator();

            while(it.hasNext()) {

                Element e = (Element) it.next();

                String name = e.getName();

                String value = e.getTextNormalize();

                List list = e.getChildren();

                sb.append("<" + name + ">");

                if(!list.isEmpty()) {

                    sb.append(XMLUtil.getChildrenText(list));

                }

                sb.append(value);

                sb.append("</" + name + ">");

            }

        }  

        return sb.toString();

    }  

}