1、接口文档

https://pay.weixin.qq.com/wiki/doc/api/cash_coupon.php?chapter=13_5

2、证书下载及证书安装

首先，商户调用微信红包接口时，服务器会进行证书验证，所以要在商户平台下载证书。在管理后台的“账户信息”里找到“安全设置”就可以下载了证书了。

商户平台：https://pay.weixin.qq.com

我们把下载好的证书解压放到目录D:/certs下。SSL接口中使用到这些证书。

接着就是向帐号中充值，因为发放现金红包将扣除商户的可用余额，所以需要预先充值，确保可用余额充足。进入“资金管理”菜单找到“现金管理”，在此进行充值，保证帐号有余额可以进行红包发放。

3、业务代码

3.1红包实体类

package com.benben.timetable.wechat.entity;

/**
 * 现金红包
 *
 * @ClassName: SendRedPack
 * @Description: TODO
 * @author 潘广伟(笨笨)
 * @date 2015年12月11日
 *
 */
public class SendRedPack {

    private String nonce_str;// 随机字符串
    private String sign;// 签名
    private String mch_billno;// 商户订单号
    private String mch_id;// 商户号
    private String wxappid;// 公众账号
    private String send_name;// 商户名称
    private String re_openid;// 用户
    private int total_amount;// 付款金额
    private int total_num;// 红包发放总人数
    private String wishing;// 红包祝福语
    private String client_ip;// Ip地址
    private String act_name;// 活动名称
    private String remark;// 备注

    public int getTotal_amount() {
        return total_amount;
    }

    public void setTotal_amount(int total_amount) {
        this.total_amount = total_amount;
    }

    public int getTotal_num() {
        return total_num;
    }

    public void setTotal_num(int total_num) {
        this.total_num = total_num;
    }

    public String getNonce_str() {
        return nonce_str;
    }

    public void setNonce_str(String nonce_str) {
        this.nonce_str = nonce_str;
    }

    public String getSign() {
        return sign;
    }

    public void setSign(String sign) {
        this.sign = sign;
    }

    public String getMch_billno() {
        return mch_billno;
    }

    public void setMch_billno(String mch_billno) {
        this.mch_billno = mch_billno;
    }

    public String getMch_id() {
        return mch_id;
    }

    public void setMch_id(String mch_id) {
        this.mch_id = mch_id;
    }

    public String getWxappid() {
        return wxappid;
    }

    public void setWxappid(String wxappid) {
        this.wxappid = wxappid;
    }

    public String getSend_name() {
        return send_name;
    }

    public void setSend_name(String send_name) {
        this.send_name = send_name;
    }

    public String getRe_openid() {
        return re_openid;
    }

    public void setRe_openid(String re_openid) {
        this.re_openid = re_openid;
    }

    public String getWishing() {
        return wishing;
    }

    public void setWishing(String wishing) {
        this.wishing = wishing;
    }

    public String getClient_ip() {
        return client_ip;
    }

    public void setClient_ip(String client_ip) {
        this.client_ip = client_ip;
    }

    public String getAct_name() {
        return act_name;
    }

    public void setAct_name(String act_name) {
        this.act_name = act_name;
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }

}

再次吐槽微信的xml格式。下划线啊！！！

3.2、生成红包数据签名

    public String createSendRedPackOrderSign(SendRedPack redPack){
        StringBuffer sign = new StringBuffer();
        sign.append("act_name=").append(redPack.getAct_name());
        sign.append("&client_ip=").append(redPack.getClient_ip());
        sign.append("&mch_billno=").append(redPack.getMch_billno());
        sign.append("&mch_id=").append(redPack.getMch_id());
        sign.append("&nonce_str=").append(redPack.getNonce_str());
        sign.append("&re_openid=").append(redPack.getRe_openid());
        sign.append("&remark=").append(redPack.getRemark());
        sign.append("&send_name=").append(redPack.getSend_name());
        sign.append("&total_amount=").append(redPack.getTotal_amount());
        sign.append("&total_num=").append(redPack.getTotal_num());
        sign.append("&wishing=").append(redPack.getWishing());
        sign.append("&wxappid=").append(redPack.getWxappid());
        sign.append("&key=").append(payKey);
        return DigestUtils.md5Hex(sign.toString()).toUpperCase();
    }

签名算法请参考：https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=4_3
之前微信支付也用到相同的签名方式：http://blog.csdn.net/jrainbow/article/details/49904065

3.3、SSL接口

private String ssl(String url,String data){
        StringBuffer message = new StringBuffer();
        try {
            KeyStore keyStore  = KeyStore.getInstance("PKCS12");
            FileInputStream instream = new FileInputStream(new File("D:/certs/apiclient_cert.p12"));
            keyStore.load(instream, mchId.toCharArray());
         // Trust own CA and all self-signed certs
            SSLContext sslcontext = SSLContexts.custom()
                    .loadKeyMaterial(keyStore, mchId.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();
            HttpPost httpost = new HttpPost(url);

            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) ");
            httpost.setEntity(new StringEntity(data, "UTF-8"));
            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(),"UTF-8"));
                    String text;
                    while ((text = bufferedReader.readLine()) != null) {
                        message.append(text);
                    }

                }
                EntityUtils.consume(entity);
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                response.close();
            }
        } catch (Exception e1) {
            e1.printStackTrace();
        } 

        return message.toString();
    }

注意：微信本身提供的demo中的ssl程序是不正确的。

3.4 发送红包

    /**
     * 现金红包
     * @Title: bindDevice
     * @return String
     * @throws
     */
    public Map<String, String> sendRedPack(SendRedPack redPack) throws Exception{
        String sign = createSendRedPackOrderSign(redPack);
        redPack.setSign(sign);

        xmlUtil.xstream().alias("xml", redPack.getClass());
        String xml = xmlUtil.xstream().toXML(redPack);
        String response = ssl(sendEedPackUrl,xml);
        Map<String, String> responseMap = xmlUtil.parseXml(response);
        return responseMap;
    }