直连商户模式和服务商模式区别：
直连商户：例如张三开了一个小程序，然后别人在这个小程序买东西，结账的时候，钱是直接打到张三的账号上的。
服务商模式：例如张三开了一个小程序，然后这个小程序中有一个开分店的功能，然后别人在分店购买东西，在结账的时候，钱是直接打到分店的负责人的账号上的
本文章说的是直连商户模式（服务商模式请看：https://blog.csdn.net/qq_26112725/article/details/131684591）
微信支付逻辑（重点）：
前端点击支付按钮，在调起微信自带支付页面之前，要往后端发一个请求，后端先是负责调用微信的 "统一下单" 接口，在调用这个接口的时候，会把本地订单号也一起发过去，然后会得到一个 prepay_id ，然后再针对 prepay_id 和一些参数做一个算法，得到相对应的签名值，然后返回给前端，然后前端就可以根据这些返回值调用支付，就可以支付了如果支付成功，那就ok了，因为有把本地的订单号一起传过去给微信那边，所以就相当于这个本地的订单号跟微信那边的订单绑定了，所以只要支付了腾讯那边的订单，那就相当于完成了本地订单。
1.申请证书，设置V3秘钥
2.设置APPid账号管理
3.maven地址
<dependency> <groupId>com.github.wechatpay-apiv3</groupId> <artifactId>wechatpay-apache-httpclient</artifactId> <version>0.4.7</version> </dependency>
4.公共参数接口
/** * 直连商户 */ public interface DirectConnection { String NOTIFY_URL = ""; //支付成功后的回调地址 String MCH_ID = ""; //商户号 String MCH_SERIAL_NO = ""; //商户证书序列号 String API_3KEY = ""; //V3密钥 String APP_ID = ""; //小程序或者公众号的ApId String privateKey = "MIIEvAIBADANBgkqhkiG9w0BAQEFAASCBKYwggSiAgEAAoIBAQDOsZnx5Nh4qK7O" + "vzbDOQu5UMtSdoZWyqOC+gFNVAB7aPAzQwgN7OAUt7G8synPRdovQ/l116dZ0ZiX"+ "XQX3Le8/o5szRH6LxpqcpFMaZg2N/HOydyTMaHI0wnZIc9BXR8aaXl7uVQnydF40"+ "FoWicge6vTCXOyjirTpS2PGKy9+hu0vx7GbX1NUDl2hNXkH54pdWn5eof1fnbh/V"+ "45q/OS7d9qnpYfs1ff+0nA=="; // 商户证书序列号对应的证书秘钥 }其中的 商户证书序列号对应的证书秘钥 在下载好的证书的这个地方：
其中红色框起来的就是商户证书序列号对应的证书秘钥：
5.下单工具类
package com.example.demo.zhifu; import cn.hutool.core.util.RandomUtil; import com.alibaba.fastjson2.JSONObject; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ObjectNode; import com.wechat.pay.contrib.apache.httpclient.WechatPayHttpClientBuilder; import com.wechat.pay.contrib.apache.httpclient.auth.PrivateKeySigner; import com.wechat.pay.contrib.apache.httpclient.auth.Verifier; import com.wechat.pay.contrib.apache.httpclient.auth.WechatPay2Credentials; import com.wechat.pay.contrib.apache.httpclient.auth.WechatPay2Validator; import com.wechat.pay.contrib.apache.httpclient.cert.CertificatesManager; import com.wechat.pay.contrib.apache.httpclient.exception.HttpCodeException; import com.wechat.pay.contrib.apache.httpclient.exception.NotFoundException; import com.wechat.pay.contrib.apache.httpclient.util.PemUtil; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.util.EntityUtils; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.nio.charset.StandardCharsets; import java.security.*; import java.util.Base64; /** * 直连商户的下单工具类 * @author [email protected] */ public class PayUtil { private CloseableHttpClient httpClient; private CertificatesManager certificatesManager; private Verifier verifier; private PrivateKey merchantPrivateKey; { try { merchantPrivateKey = PemUtil.loadPrivateKey(new ByteArrayInputStream(DirectConnection.privateKey.getBytes("utf-8"))); // 获取证书管理器实例 certificatesManager = CertificatesManager.getInstance(); // 向证书管理器增加需要自动更新平台证书的商户信息 certificatesManager.putMerchant(DirectConnection.MCH_ID, new WechatPay2Credentials(DirectConnection.MCH_ID, new PrivateKeySigner(DirectConnection.MCH_SERIAL_NO, merchantPrivateKey)), DirectConnection.API_3KEY.getBytes(StandardCharsets.UTF_8)); // 从证书管理器中获取verifier verifier = certificatesManager.getVerifier(DirectConnection.MCH_ID); httpClient = WechatPayHttpClientBuilder.create() .withMerchant(DirectConnection.MCH_ID, DirectConnection.MCH_SERIAL_NO, merchantPrivateKey) .withValidator(new WechatPay2Validator(certificatesManager.getVerifier(DirectConnection.MCH_ID))) .build(); } catch (IOException | GeneralSecurityException | HttpCodeException | NotFoundException e) { throw new RuntimeException(e); } } /** * 统一下单，获取到 prepay_id ，然后获取签名，调起 * @param total * @param description * @return * @throws Exception */ public String requestwxChatPay(String orderSn, int total, String description,String openid) throws Exception { HttpPost httpPost = new HttpPost("https://api.mch.weixin.qq.com/v3/pay/transactions/jsapi"); httpPost.addHeader("Accept", "application/json"); httpPost.addHeader("Content-type", "application/json; charset=utf-8"); ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectMapper objectMapper = new ObjectMapper(); //组合请求参数JSON格式 ObjectNode rootNode = objectMapper.createObjectNode(); rootNode.put("mchid", DirectConnection.MCH_ID) .put("appid", DirectConnection.APP_ID) .put("notify_url", DirectConnection.NOTIFY_URL + "returnNotify") .put("description", description) .put("out_trade_no", orderSn); rootNode.putObject("amount") // total：金额，以分为单位，假如是10块钱，那就要写 1000 .put("total", total) .put("currency", "CNY"); rootNode.putObject("payer") // openid：用户在该小程序或者公众号下的openid .put("openid", openid); try { objectMapper.writeValue(bos, rootNode); httpPost.setEntity(new StringEntity(bos.toString("UTF-8"), "UTF-8")); //获取预支付ID CloseableHttpResponse response = httpClient.execute(httpPost); String bodyAsString = EntityUtils.toString(response.getEntity()); //微信成功响应 int statusCode = response.getStatusLine().getStatusCode(); if (statusCode == 200) { //时间戳 String timestamp = System.currentTimeMillis() / 1000 + ""; //随机字符串 String nonce = RandomUtil.randomString(32); StringBuilder builder = new StringBuilder(); // Appid builder.append(DirectConnection.APP_ID).append("\n"); // 时间戳 builder.append(timestamp).append("\n"); // 随机字符串 builder.append(nonce).append("\n"); JsonNode jsonNode = objectMapper.readTree(bodyAsString); // 预支付会话ID builder.append("prepay_id=").append(jsonNode.get("prepay_id").textValue()).append("\n"); //获取签名 String sign = this.sign(builder.toString().getBytes("utf-8"), merchantPrivateKey); JSONObject jsonMap = new JSONObject(); jsonMap.put("noncestr", nonce); jsonMap.put("timestamp", timestamp); jsonMap.put("prepayid", jsonNode.get("prepay_id").textValue()); jsonMap.put("sign", sign); jsonMap.put("appid", DirectConnection.APP_ID); jsonMap.put("partnerid", DirectConnection.MCH_ID); return jsonMap.toJSONString();//响应签名数据，前端拿着响应数据调起微信SDK } } catch (Exception e) { e.printStackTrace(); } return null; } /** /** * 计算签名 * * @param message * @param yourPrivateKey * @return */ private String sign(byte[] message, PrivateKey yourPrivateKey) { try { Signature sign = Signature.getInstance("SHA256withRSA"); sign.initSign(yourPrivateKey); sign.update(message); return Base64.getEncoder().encodeToString(sign.sign()); } catch (NoSuchAlgorithmException | InvalidKeyException | SignatureException e) { e.printStackTrace(); } return ""; } }
6.回调签名工具类
package com.example.demo.zhifu; /** * @Description: * @Author sk * @Date: 2023/7/5 14:31 */ import javax.crypto.Cipher; import javax.crypto.NoSuchPaddingException; import javax.crypto.spec.GCMParameterSpec; import javax.crypto.spec.SecretKeySpec; import java.io.IOException; import java.security.GeneralSecurityException; import java.security.InvalidAlgorithmParameterException; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.util.Base64; /** * 回调签名配置 * @author [email protected] */ public class AesUtil { static final int KEY_LENGTH_BYTE = 32; static final int TAG_LENGTH_BIT = 128; private final byte[] aesKey; public AesUtil(byte[] key) { if (key.length != KEY_LENGTH_BYTE) { throw new IllegalArgumentException("无效的ApiV3Key，长度必须为32个字节"); } this.aesKey = key; } public String decryptToString(byte[] associatedData, byte[] nonce, String ciphertext) throws GeneralSecurityException, IOException { try { Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding"); SecretKeySpec key = new SecretKeySpec(aesKey, "AES"); GCMParameterSpec spec = new GCMParameterSpec(TAG_LENGTH_BIT, nonce); cipher.init(Cipher.DECRYPT_MODE, key, spec); cipher.updateAAD(associatedData); return new String(cipher.doFinal(Base64.getDecoder().decode(ciphertext)), "utf-8"); } catch (NoSuchAlgorithmException | NoSuchPaddingException e) { throw new IllegalStateException(e); } catch (InvalidKeyException | InvalidAlgorithmParameterException e) { throw new IllegalArgumentException(e); } } }
7.下单的controller
package com.example.demo.zhifu; import cn.hutool.json.JSONObject; import cn.hutool.json.JSONUtil; import org.springframework.web.bind.annotation.*; import java.nio.charset.StandardCharsets; import java.util.HashMap; import java.util.Map; /** * @Description: * @Author sk * @Date: 2023/7/5 19:10 */ @RestController @RequestMapping(value = "/pay") public class payController { /** * 预支付下单 * @param orderSn 订单号 * @param total 分 * @param description 描述 * @return */ @GetMapping(value = "/getPay") public String getPay(String orderSn,int total , String description) { PayUtil payUtil = new PayUtil(); try { return payUtil.requestwxChatPay(orderSn, total, description, "oYgFI91D00GpCwccdnKDR4KNxI4k"); } catch (Exception e) { throw new RuntimeException(e); } } // 支付回调 @PostMapping(value = "/returnNotify") public Map returnNotify(@RequestBody JSONObject jsonObject) { // v3 私钥 String key = "xxxxx"; String json = jsonObject.toString(); String associated_data = (String) JSONUtil.getByPath(JSONUtil.parse(json), "resource.associated_data"); String ciphertext = (String) JSONUtil.getByPath(JSONUtil.parse(json), "resource.ciphertext"); String nonce = (String) JSONUtil.getByPath(JSONUtil.parse(json), "resource.nonce"); try { String decryptData = new AesUtil(key.getBytes(StandardCharsets.UTF_8)).decryptToString(associated_data.getBytes(StandardCharsets.UTF_8), nonce.getBytes(StandardCharsets.UTF_8), ciphertext); System.out.println("decryptData = " + decryptData); //TODO 业务校验 } catch (Exception e) { e.printStackTrace(); } HashMap<String, String> stringStringHashMap = new HashMap<>(); stringStringHashMap.put("code","200"); stringStringHashMap.put("message","返回成功"); // 返回这个说明应答成功 return stringStringHashMap; } }