微信小程序支付Jsapi下单Java版保姆级教程_Java

前置环境

jdk：21
maven：3.9.9

需要自己去注册申请微信小程序和微信支付平台商户号绑定

注意上述两张图片是微信公众平台和微信支付平台，两个地方的appid和商户号必须得对的上

支付产品许可申请

需要把这个申请上，这个就不做赘述了，这个跟着申请内容填资料就行了。

支付参数申请

这里点击进去后申请一个证书

然后进入这个api安全，这里比较关键，注意操作步骤。

这里的密钥记清楚，最好新建一个文件做一个备注。

点击这个下载，按照这个下载证书文档，操作，这里注意的是这个outputfilepath以及apiclinet_key.pem地址

apiclinet_key.pem地址

这个地址需要在解密回调里面去申请，同样里面的密钥也需要记住。

然后按照这个工具里面的操作进行来回复制就会得到一个文件，这个文件里面的apiclinet_key.pem存放的地址。

这样操作下来我们就得到一个

java -jar certificatedownloader.jar -k czbk5123643ffduv3 -m 1622408443 -f e:\code\ai\乞讨\1622408443_20250305_cert\apiclient_key.pem -s 495f550990e8ff3fc72c7 -o e:\www\code

运行后

得到密钥文件。至此我们所需要的文件已全部收集齐全。

代码：

application.yaml

cant:
  wechat:
    # 微信公众平台里面的小程序appid
    appid: wx8b8656de482b
    # 商户号
    mchid: 1622408443
    # 商户api证书里面的序列号
    mchserialno: 405172e0770000864ce6a4136411
    # 解密回调的密钥
    apiv3key: cwxpay435434323ffduv3
    # 这个是解密回调也就是生成的（微信支付商户平台证书工具）
    privatekeyfilepath: e:\code\ai\乞讨\1622408443_20250307_cert\apiclient_cert.pem
    # 这个是通cmd生成的
    wechatpaycertfilepath: e:\www\code\wechatpay_54d388b975fd231c6ca45be67f78d0e4181ac0c2.pem
    # 支付成功回调地址
    notifyurl: https://taluop.top/cant/notify

导入依赖

<dependency>
            <groupid>com.github.wechatpay-apiv3</groupid>
            <artifactid>wechatpay-java</artifactid>
            <version>0.2.10</version>
        </dependency>

配置类

@component
@configurationproperties(prefix = "cant.wechat")
@data
@enableconfigurationproperties
public class wechatproperties {
    private string appid; //小程序的appid
    private string secret; //小程序的秘钥
    private string mchid; //商户号
    private string mchserialno; //商户api证书的证书序列号
    private string privatekeyfilepath; //商户私钥文件
    private string apiv3key; //证书解密的密钥
    private string wechatpaycertfilepath; //平台证书
    private string notifyurl; //支付成功的回调地址
    private string refundnotifyurl; //退款成功的回调地址

}

工具类

/**
 * 微信支付工具类
 */
@component
public class wechatpayutil {

    //微信支付下单接口地址
    public static final string jsapi = "https://api.mch.weixin.qq.com/v3/pay/transactions/jsapi";

    //申请退款接口地址
    public static final string refunds = "https://api.mch.weixin.qq.com/v3/refund/domestic/refunds";

    @autowired
    private wechatproperties wechatproperties;

    /**
     * 获取调用微信接口的客户端工具对象
     *
     * @return
     */
    private closeablehttpclient getclient() {
        privatekey merchantprivatekey = null;
        try {
            // merchantprivatekey商户api私钥，如何加载商户api私钥请看常见问题
            merchantprivatekey = pemutil.loadprivatekey(new fileinputstream(new file(wechatproperties.getprivatekeyfilepath())));
            // 加载平台证书文件
            x509certificate x509certificate = pemutil.loadcertificate(new fileinputstream(new file(wechatproperties.getwechatpaycertfilepath())));
            // wechatpaycertificates微信支付平台证书列表。你也可以使用“定时更新平台证书功能”
            list<x509certificate> wechatpaycertificates = arrays.aslist(x509certificate);

            wechatpayhttpclientbuilder builder = wechatpayhttpclientbuilder.create()
                    .withmerchant(wechatproperties.getmchid(), wechatproperties.getmchserialno(), merchantprivatekey)
                    .withwechatpay(wechatpaycertificates);

            // 通过wechatpayhttpclientbuilder构造的httpclient，会自动的处理签名和验签
            closeablehttpclient httpclient = builder.build();
            return httpclient;
        } catch (filenotfoundexception e) {
            e.printstacktrace();
            return null;
        }
    }

    /**
     * 发送post方式请求
     *
     * @param url
     * @param body
     * @return
     */
    private string post(string url, string body) throws exception {
        closeablehttpclient httpclient = getclient();

        httppost httppost = new httppost(url);
        httppost.addheader(httpheaders.accept, contenttype.application_json.tostring());
        httppost.addheader(httpheaders.content_type, contenttype.application_json.tostring());
        httppost.addheader("wechatpay-serial", wechatproperties.getmchserialno());
        httppost.setentity(new stringentity(body, "utf-8"));

        closeablehttpresponse response = httpclient.execute(httppost);
        try {
            string bodyasstring = entityutils.tostring(response.getentity());
            return bodyasstring;
        } finally {
            httpclient.close();
            response.close();
        }
    }

    /**
     * jsapi下单
     *
     * @param ordernum    商户订单号
     * @param total       总金额
     * @param description 商品描述
     * @param openid      微信用户的openid
     * @return
     */
    private string jsapi(string ordernum, bigdecimal total, string description, string openid) throws exception {
        jsonobject jsonobject = new jsonobject();
        jsonobject.put("appid", wechatproperties.getappid());
        jsonobject.put("mchid", wechatproperties.getmchid());
        jsonobject.put("description", description);
        jsonobject.put("out_trade_no", ordernum);
        jsonobject.put("notify_url", wechatproperties.getnotifyurl());

        jsonobject amount = new jsonobject();
        amount.put("total", total.multiply(new bigdecimal(100)).setscale(2, bigdecimal.round_half_up).intvalue());
        amount.put("currency", "cny");

        jsonobject.put("amount", amount);

        jsonobject payer = new jsonobject();
        payer.put("openid", openid);

        jsonobject.put("payer", payer);

        string body = jsonobject.tojsonstring();
        return post(jsapi, body);
    }

    /**
     * 小程序支付
     *
     * @param ordernum    商户订单号
     * @param total       金额，单位 元
     * @param description 商品描述
     * @param openid      微信用户的openid
     * @return
     */
    public jsonobject pay(string ordernum, bigdecimal total, string description, string openid) throws exception {
        //统一下单，生成预支付交易单
        string bodyasstring = jsapi(ordernum, total, description, openid);
        //解析返回结果
        jsonobject jsonobject = json.parseobject(bodyasstring);

        system.out.println(jsonobject);

        string prepayid = jsonobject.getstring("prepay_id");
        if (prepayid != null) {
            string timestamp = string.valueof(system.currenttimemillis() / 1000);
            string noncestr = randomstringutils.randomnumeric(32);
            arraylist<object> list = new arraylist<>();
            list.add(wechatproperties.getappid());
            list.add(timestamp);
            list.add(noncestr);
            list.add("prepay_id=" + prepayid);
            //二次签名，调起支付需要重新签名
            stringbuilder stringbuilder = new stringbuilder();
            for (object o : list) {
                stringbuilder.append(o).append("\n");
            }
            string signmessage = stringbuilder.tostring();
            byte[] message = signmessage.getbytes();

            signature signature = signature.getinstance("sha256withrsa");
            signature.initsign(pemutil.loadprivatekey(new fileinputstream(new file(wechatproperties.getprivatekeyfilepath()))));
            signature.update(message);
            string packagesign = base64.getencoder().encodetostring(signature.sign());

            //构造数据给微信小程序，用于调起微信支付
            jsonobject jo = new jsonobject();
            jo.put("timestamp", timestamp);
            jo.put("noncestr", noncestr);
            jo.put("package", "prepay_id=" + prepayid);
            jo.put("signtype", "rsa");
            jo.put("paysign", packagesign);

            return jo;
        }
        return jsonobject;
    }
    /**
     * 发送get方式请求
     *
     * @param url
     * @return
     */
    private string get(string url) throws exception {
        closeablehttpclient httpclient = getclient();

        httpget httpget = new httpget(url);
        httpget.addheader(httpheaders.accept, contenttype.application_json.tostring());
        httpget.addheader(httpheaders.content_type, contenttype.application_json.tostring());
        httpget.addheader("wechatpay-serial", wechatproperties.getmchserialno());

        closeablehttpresponse response = httpclient.execute(httpget);
        try {
            string bodyasstring = entityutils.tostring(response.getentity());
            return bodyasstring;
        } finally {
            httpclient.close();
            response.close();
        }
    }


    /**
     * 申请退款
     *
     * @param outtradeno    商户订单号
     * @param outrefundno   商户退款单号
     * @param refund        退款金额
     * @param total         原订单金额
     * @return
     */
    public string refund(string outtradeno, string outrefundno, bigdecimal refund, bigdecimal total) throws exception {
        jsonobject jsonobject = new jsonobject();
        jsonobject.put("out_trade_no", outtradeno);
        jsonobject.put("out_refund_no", outrefundno);

        jsonobject amount = new jsonobject();
        amount.put("refund", refund.multiply(new bigdecimal(100)).setscale(2, bigdecimal.round_half_up).intvalue());
        amount.put("total", total.multiply(new bigdecimal(100)).setscale(2, bigdecimal.round_half_up).intvalue());
        amount.put("currency", "cny");

        jsonobject.put("amount", amount);
        jsonobject.put("notify_url", wechatproperties.getrefundnotifyurl());

        string body = jsonobject.tojsonstring();

        //调用申请退款接口
        return post(refunds, body);
    }
}

遇到的问题：

应答的状态码不为200-299，商户证书序列号有误。

你需要找到最近操作的证书序列号
找不到证书序列号对应的证书

这个地址对应的看一下是否是最新的
java hotspot(tm) 64-bit server vm warning: sharing is only supported for boot loader classes because bootstrap classpath has been appendedranh

这个需要的是apiclient_key.pem文件，这个是由apiclient_cert.pem文件加序列号生成的文件。