<dependency>
    <groupId>com.ning</groupId>
    <artifactId>async-http-client</artifactId>
    <version>1.8.13</version>
</dependency>
<dependency>
    <groupId>com.thoughtworks.xstream</groupId>
    <artifactId>xstream</artifactId>
    <version>1.4.7</version>
</dependency>
<dependency>
    <groupId>com.gson</groupId>
    <artifactId>wechat</artifactId>
    <version>1.0.8</version>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.14.4</version>
</dependency>
<dependency>
    <groupId>com.squareup.okhttp</groupId>
    <artifactId>okhttp</artifactId>
    <version>2.7.5</version>
</dependency>
<dependency>
    <groupId>commons-httpclient</groupId>
    <artifactId>commons-httpclient</artifactId>
    <version>3.1</version>
</dependency>
<dependency>
    <groupId>org.jdom</groupId>
    <artifactId>jdom</artifactId>
    <version>1.1</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.7</version>
</dependency>

import java.security.MessageDigest;

public class MD5Util {

    private static String byteArrayToHexString(byte b[]) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++)
            resultSb.append(byteToHexString(b[i]));

        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
            n += 256;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String origin, String charsetname) {
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetname == null || "".equals(charsetname))
                resultString = byteArrayToHexString(md.digest(resultString
                        .getBytes()));
            else
                resultString = byteArrayToHexString(md.digest(resultString
                        .getBytes(charsetname)));
        } catch (Exception exception) {
        }
        return resultString;
    }

    private static final String hexDigits[] = { "0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

}

import org.apache.http.Consts;
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLContexts;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;

import javax.net.ssl.SSLContext;
import java.io.*;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.KeyStore;
import java.util.*;

/**
 * Created by Administrator on 2017/1/4.
 */
public class WxPayUtil {

    //微信支付key
    public static String API_KEY="*********";
    //公众号appid
    public static String APPID="********";
    //商户号id
    public static String MCH_ID="*******";

    //随机字符串生成
    public static String getRandomString(int length) { //length表示生成字符串的长度
        String base = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            int number = random.nextInt(base.length());
            sb.append(base.charAt(number));
        }
        return sb.toString();
    }

    //请求xml组装
    public static String getRequestXml(SortedMap<String,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 key = (String)entry.getKey();
            String value = (String)entry.getValue();
            if ("attach".equalsIgnoreCase(key)||"body".equalsIgnoreCase(key)||"sign".equalsIgnoreCase(key)) {
                sb.append("<"+key+">"+"<![CDATA["+value+"]]></"+key+">");
            }else {
                sb.append("<"+key+">"+value+"</"+key+">");
            }
        }
        sb.append("</xml>");
        return sb.toString();
    }

    //生成签名
    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=" + API_KEY);
        System.out.println(sb.toString());
        String sign = MD5Util.MD5Encode(sb.toString(), characterEncoding).toUpperCase();
        return sign;
    }

    /**
     * 验证回调签名
     * @param map
     * @return
     */
    public static boolean isTenpaySign(Map<String, String> map) {
        String charset = "utf-8";
        String signFromAPIResponse = map.get("sign");
        if (signFromAPIResponse == null || signFromAPIResponse.equals("")) {
             System.out.println("API返回的数据签名数据不存在，有可能被第三方篡改!!!");
             return false;
        }
        System.out.println("服务器回包里面的签名是:" + signFromAPIResponse);
        //过滤空 设置 TreeMap
        SortedMap<String,String> packageParams = new TreeMap<>();
        for (String parameter : map.keySet()) {
            String parameterValue = map.get(parameter);
            String v = "";
            if (null != parameterValue) {
            v = parameterValue.trim();
            }
            packageParams.put(parameter, v);
        }

        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);

        //将API返回的数据根据用签名算法进行计算新的签名，用来跟API返回的签名进行比较
        //算出签名
        String resultSign = "";
        String tobesign = sb.toString();
        if (null == charset || "".equals(charset)) {
            resultSign = MD5Util.MD5Encode(tobesign, "utf-8").toUpperCase();
        } else {
            resultSign = MD5Util.MD5Encode(tobesign, "utf-8").toUpperCase();
        }
        String tenpaySign = ((String)packageParams.get("sign")).toUpperCase();
        return tenpaySign.equals(resultSign);
    }

    //请求方法
    public static String httpsRequest(String requestUrl, String requestMethod, String outputStr) {
        try {

            URL url = new URL(requestUrl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setUseCaches(false);
            // 设置请求方式（GET/POST）
            conn.setRequestMethod(requestMethod);
            conn.setRequestProperty("content-type", "application/x-www-form-urlencoded");
            // 当outputStr不为null时向输出流写数据
            if (null != outputStr) {
                OutputStream outputStream = conn.getOutputStream();
                // 注意编码格式
                outputStream.write(outputStr.getBytes("UTF-8"));
                outputStream.close();
            }
            // 从输入流读取返回内容
            InputStream inputStream = conn.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);
            }
            // 释放资源
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();
            inputStream = null;
            conn.disconnect();
            return buffer.toString();
        } catch (ConnectException ce) {
            System.out.println("连接超时：{}"+ ce);
        } catch (Exception e) {
            System.out.println("https请求异常：{}"+ e);
        }
        return null;
    }

    //退款的请求方法
    public static String httpsRequest2(String requestUrl, String requestMethod, String outputStr) throws Exception {
        KeyStore keyStore  = KeyStore.getInstance("PKCS12");
        StringBuilder res = new StringBuilder("");
        FileInputStream instream = new FileInputStream(new File("/home/apiclient_cert.p12"));
        try {
            keyStore.load(instream, "".toCharArray());
        } finally {
            instream.close();
        }

        // Trust own CA and all self-signed certs
        SSLContext sslcontext = SSLContexts.custom()
                .loadKeyMaterial(keyStore, "1313329201".toCharArray())
                .build();
        // Allow TLSv1 protocol only
        SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
                sslcontext,
                new String[] { "TLSv1" },
                null,
                SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER);
        CloseableHttpClient httpclient = HttpClients.custom()
                .setSSLSocketFactory(sslsf)
                .build();
        try {

            HttpPost httpost = new HttpPost("https://api.mch.weixin.qq.com/secapi/pay/refund");
            httpost.addHeader("Connection", "keep-alive");
            httpost.addHeader("Accept", "*/*");
            httpost.addHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");
            httpost.addHeader("Host", "api.mch.weixin.qq.com");
            httpost.addHeader("X-Requested-With", "XMLHttpRequest");
            httpost.addHeader("Cache-Control", "max-age=0");
            httpost.addHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0) ");
            StringEntity entity2 = new StringEntity(outputStr , Consts.UTF_8);
            httpost.setEntity(entity2);
            System.out.println("executing request" + httpost.getRequestLine());

            CloseableHttpResponse response = httpclient.execute(httpost);

            try {
                HttpEntity entity = response.getEntity();

                System.out.println("----------------------------------------");
                System.out.println(response.getStatusLine());
                if (entity != null) {
                    System.out.println("Response content length: " + entity.getContentLength());
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(entity.getContent()));
                    String text = "";
                    res.append(text);
                    while ((text = bufferedReader.readLine()) != null) {
                        res.append(text);
                        System.out.println(text);
                    }

                }
                EntityUtils.consume(entity);
            } finally {
                response.close();
            }
        } finally {
            httpclient.close();
        }
        return  res.toString();

    }

    //xml解析
    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 = getChildrenText(children);
            }

            m.put(k, v);
        }

        //关闭流
        in.close();

        return m;
    }

    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(getChildrenText(list));
                }
                sb.append(value);
                sb.append("</" + name + ">");
            }
        }

        return sb.toString();
    }
}

import com.jumei.util.wxutils.WxPayUtil;
import org.apache.log4j.Logger;
import org.jdom.JDOMException;

import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.math.BigDecimal;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.UUID;

/**
 *
 * 支付基本信息
 * @author zhangli
 * @date 2016年3月28日 下午2:35:24
 *
 *
 * 1.需要支付的信息  ：
 *         用户支付  支付相关业务 支付金额  回调业务
 * 2.第三方支付需要的信息：
 *         trade_no,subject,body,total_fee,notify_url
 *
 */
public class PayUtils {
    protected static Logger logger = Logger.getLogger(PayUtils.class);
    public static String wxnotify = "/api/json/money/wxpay/succ";

    /**
     * @param totalAmount    支付金额
     * @param description    描述
     * @param request
     * @return
     */
    public static Map<String, Object> toPay(BigDecimal totalAmount,String description,String openId, HttpServletRequest request) {
        String sym = request.getRequestURL().toString().split("/api/")[0];
        String trade_no0 = UUID.randomUUID().toString().replaceAll("-", "").toLowerCase();
        String trade_no = trade_no0.substring(0,32);
        Map<String, String> map = weixinPrePay(trade_no,totalAmount,description,openId,sym,request);
        SortedMap<String, Object> finalpackage = new TreeMap<String, Object>();
        finalpackage.put("appId", WxPayUtil.APPID);
        finalpackage.put("timeStamp", String.valueOf(System.currentTimeMillis() / 1000));
        finalpackage.put("nonceStr", WxPayUtil.getRandomString(32));
        finalpackage.put("package", "prepay_id="+map.get("prepay_id"));
        finalpackage.put("signType", "MD5");
        String sign = WxPayUtil.createSign("UTF-8", finalpackage);
        finalpackage.put("paySign", sign);
        return finalpackage;
    }

    /**
     * 预支付
     * @param trade_no 商户订单号 **必输** <br/>
     * @param totalAmount 总金额 **必输** 注意 ，为货币最小单位，比如人民币时，单位为分<br/>
     * @param description 商品描述 **必输** <br/>
     * @param openid 用户标示
     * @param sym 回调地址
     * @param request
     * @return
     */
    @SuppressWarnings("unchecked")
    public static Map<String, String> weixinPrePay(String trade_no,BigDecimal totalAmount,
                                            String description, String openid,String sym, HttpServletRequest request) {
        SortedMap<String, Object> parameterMap = new TreeMap<String, Object>();
        parameterMap.put("appid", WxPayUtil.APPID);
        parameterMap.put("mch_id", WxPayUtil.MCH_ID);
        parameterMap.put("nonce_str", WxPayUtil.getRandomString(32));
        parameterMap.put("body", description);
        parameterMap.put("out_trade_no", trade_no);
        parameterMap.put("fee_type", "CNY");
        BigDecimal total = totalAmount.multiply(new BigDecimal(100));
        java.text.DecimalFormat df=new java.text.DecimalFormat("0");
        parameterMap.put("total_fee", df.format(total));
        parameterMap.put("spbill_create_ip", request.getRemoteAddr());
        parameterMap.put("notify_url", sym + wxnotify);
        parameterMap.put("trade_type", "JSAPI");
        //trade_type为JSAPI是 openid为必填项
        parameterMap.put("openid", openid);
        System.out.println("");
        String sign = WxPayUtil.createSign("UTF-8", parameterMap);
        System.out.println("jiner2");
        parameterMap.put("sign", sign);
        String requestXML = WxPayUtil.getRequestXml(parameterMap);
        System.out.println(requestXML);
        String result = WxPayUtil.httpsRequest("https://api.mch.weixin.qq.com/pay/unifiedorder", "POST",requestXML);
        System.out.println(result);
        Map<String, String> map = null;
        try {
            map = WxPayUtil.doXMLParse(result);
        } catch (JDOMException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return map;
    }

}

Map<String,Object>map = PayUtils.toPay(
                    totalAmount,
                    description,
                    openid,
                    request
            );

<script src="http://res.wx.qq.com/open/js/jweixin-1.0.0.js" type="text/javascript"></script>

//调用微信JS api 支付
function jsApiCall(){
    $.ajax({
        url: urlcore+"/money/get/alipay/order/sign?rechargeOrPay=2&orderMoney=0.01&PayType=3&openid=oDqAOw2aXVR4BigutiXjiPXC5QW4",
        type: "get",
        dataType: ‘jsonp‘,
        contentType: "application/json;charset=utf-8",
        success:function(data){        
            var d = data.data;
             WeixinJSBridge.invoke(
                ‘getBrandWCPayRequest‘,
                {
                   "appId":d.appId,     //公众号名称，由商户传入     
                   "timeStamp":d.timeStamp,         //时间戳，自1970年以来的秒数     
                   "nonceStr":d.nonceStr, //随机串     
                   "package":d.package,     
                   "signType":"MD5",         //微信签名方式：     
                   "paySign":d.paySign //微信签名 
               },
                function (res){
                    WeixinJSBridge.log(res.err_msg);
                    alert(res.err_code + res.err_desc + res.err_msg);
                    }
                );
        },
        error:function() {
            /* Act on the event */
            alert("error");
        }
    });
   
}