Withdrawal of wechat applet (enterprise payment to change)

demand

Implement a cash withdrawal function in wechat applet , The money withdrawn actually comes from other functions in the system .

Of course, this function , You need a wechat payment merchant number , And there should be sufficient balance in the account .

Preparation

1、 Log in to the official website of wechat merchant platform ： Wechat payment - China's leading third-party payment platform ｜ Wechat payment provides a safe and fast payment method (qq.com)

2、 Find the enterprise in the product center and pay in change , And open the enterprise payment to change function

3、 find AppID Account management , Add Association AppID

4、 Bind wechat merchant ID to applet

5、 apply API Certificates and APIv2 secret key , Keep it well , We'll use it later

notes ：API The suffix of the certificate file is .p12

6、 Get merchant number

Code implementation （SpringBoot）

1、 Introduce relevant official dependencies

<dependency>
    <groupId>com.github.wxpay</groupId>
    <artifactId>wxpay-sdk</artifactId>
    <version>0.0.3</version>
</dependency>

2、 stay yaml File add configuration

withDraw:
	apiKey: xxxxxxxx
     mchid: xxxxxx
     mch_appid: xxxxxxxxx
     // This path represents resouce root directory 
     certPath: /xxxxxxxx.p12
     count: 10
     quota: 200

3、 Write configuration classes

@Component
public class WithDrawConfig implements WXPayConfig {
    
    // from yaml Injection allocation 
	@Value("${withDraw.mch_appid}")
	private String mch_appid;
	@Value("${withDraw.apiKey}")
	private String apiKey;
	@Value("${withDraw.mchid}")
	private String mchid;
	@Value("${withDraw.certPath}")
	private String certPath;

	@Override
	public String getAppID() {
    
		return mch_appid;
	}

	@Override
	public String getMchID() {
    
		return mchid;
	}

	@Override
	public String getKey() {
    
		return apiKey;
	}

	@Override
	public InputStream getCertStream() {
    
		// To get the certificate , The certificate is recommended to be placed in resource Under the table of contents 
		return this.getClass().getResourceAsStream(certPath);
	}

	@Override
	public int getHttpConnectTimeoutMs() {
    
		return 8000;
	}

	@Override
	public int getHttpReadTimeoutMs() {
    
		return 10000;
	}
}

4、 Prepare withdrawal tools

@Slf4j
@Component
@RequiredArgsConstructor
public class WithDrawUtils {
    
	@Value("${withDraw.mch_appid}")
	private String mch_appid;

	@Value("${withDraw.mchid}")
	private String mchid;

	@Value("${withDraw.apiKey}")
	private String apiKey;

	private final WithDrawConfig withDrawConfig;

    // Generate order number date time + Random character 
	public String getOrderNumber() {
    
		SimpleDateFormat date = new SimpleDateFormat("yyyyMMddHHmmss");
		return date.format(new Date()) + RandomStringUtils.randomNumeric(4);
	}

	public Map<String, String> fillRequest(Map<String, String> reqData) throws Exception {
    
		reqData.put("mch_appid", mch_appid);
		reqData.put("mchid", mchid);
		reqData.put("nonce_str", WXPayUtil.generateNonceStr().toUpperCase());
		reqData.put("sign", WXPayUtil.generateSignature(reqData, apiKey, WXPayConstants.SignType.MD5));
		return reqData;
	}

	public String getMd5ByString(String str) {
    
		StringBuilder hexString = new StringBuilder();
		try {
    
			MessageDigest mdTemp = MessageDigest.getInstance("MD5");
			mdTemp.update(str.getBytes());
			byte[] hash = mdTemp.digest();
			for (byte b : hash) {
    
				if ((0xff & b) < 0x10) {
    
					hexString.append("0").append(Integer.toHexString((0xFF & b)));
				} else {
    
					hexString.append(Integer.toHexString(0xFF & b));
				}
			}
		} catch (NoSuchAlgorithmException e) {
    
			e.printStackTrace();
		}
		return hexString.toString();
	}

	/** *  Convert objects directly to String Type of  XML Output  * * @param obj * @return */
	public String convertToXml(Object obj) {
    
		//  Create output stream 
		StringWriter sw = new StringWriter();
		try {
    
			//  utilize jdk Implementation of the built-in conversion class in 
			JAXBContext context = JAXBContext.newInstance(obj.getClass());

			Marshaller marshaller = context.createMarshaller();
			//  format xml Format of output 
			marshaller.setProperty(Marshaller.JAXB_FRAGMENT,
					Boolean.TRUE);
			//  Converting objects into output streams xml
			marshaller.marshal(obj, sw);
		} catch (JAXBException e) {
    
			e.printStackTrace();
		}
		return sw.toString();
	}

	public String getRestInstance(String url, String data) throws Exception {
    
		String UTF8 = "UTF-8";
		URL httpUrl = new URL(url);
		char[] password = mchid.toCharArray();// Certificate password 
		InputStream certStream = withDrawConfig.getCertStream();// Get the stream of certificates 
		KeyStore ks = KeyStore.getInstance("PKCS12");
		ks.load(certStream, password);
		//  Instantiate the keystore  &  Initialize the key factory 
		KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
		kmf.init(ks, password);
		SSLContext sslContext = SSLContext.getInstance("TLS");
		sslContext.init(kmf.getKeyManagers(), (TrustManager[]) null, new SecureRandom());
		HttpsURLConnection.setDefaultSSLSocketFactory(sslContext.getSocketFactory());
		HttpURLConnection httpURLConnection = (HttpURLConnection) httpUrl.openConnection();
		httpURLConnection.setDoOutput(true);
		httpURLConnection.setRequestMethod("POST");
		httpURLConnection.setConnectTimeout(withDrawConfig.getHttpConnectTimeoutMs());
		httpURLConnection.setReadTimeout(withDrawConfig.getHttpReadTimeoutMs());
		httpURLConnection.connect();
		OutputStream outputStream = httpURLConnection.getOutputStream();
		outputStream.write(data.getBytes(UTF8));
		InputStream inputStream = httpURLConnection.getInputStream();
		BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, UTF8));
		StringBuilder stringBuffer = new StringBuilder();
		String line;

		while ((line = bufferedReader.readLine()) != null) {
    
			stringBuffer.append(line);
		}

		String resp = stringBuffer.toString();
		try {
    
			bufferedReader.close();
		} catch (IOException ignored) {
    
		}

		try {
    
			inputStream.close();
		} catch (IOException ignored) {
    
		}

		try {
    
			outputStream.close();
		} catch (IOException ignored) {
    
		}

		if (certStream != null) {
    
			try {
    
				certStream.close();
			} catch (IOException ignored) {
    
			}
		}
		return resp;
	}
}

5、 Withdrawal business realization

Official interface document ：【 Wechat payment 】 Payment developer documentation (qq.com)

// Start withdrawing cash , Generate order number 
String orderNumber = withDrawUtils.getOrderNumber();
// Customized entity class that encapsulates the required parameters for withdrawal 
WithDrawDTO withDrawDTO = new WithDrawDTO();
withDrawDTO.setPartner_trade_no(orderNumber);
withDrawDTO.setDesc("xxxxx");
withDrawDTO.setAmount(appletWithDrawDTO.getAmount());
// This parameter represents , Enable real name verification , You can also turn off , See the parameter description in the official document for details 
withDrawDTO.setCheck_name("FORCE_CHECK");
withDrawDTO.setRe_user_name(appletWithDrawDTO.getName());
// Wechat applet users openid
withDrawDTO.setOpenid(wxUser.getOpenid());
Map<String, String> params = JSON.parseObject(JSON.toJSONString(withDrawDTO), new TypeReference<Map<String, String>>() {
    
});
params = withDrawUtils.fillRequest(params);
withDrawDTO.setNonce_str(params.get("nonce_str"));
withDrawDTO.setMchid(params.get("mchid"));
withDrawDTO.setMch_appid(params.get("mch_appid"));
withDrawDTO.setSign(params.get("sign"));
String url = "https://api.mch.weixin.qq.com/mmpaymkttransfers/promotion/transfers";
String post = withDrawUtils.getRestInstance(url, withDrawUtils.convertToXml(withDrawDTO));
Map<String, String> result = WXPayUtil.xmlToMap(post);
//result Is the return parameter after calling the interface , You can judge whether it is successful according to the return parameters 

WithDrawEnum resultEnum;
if ("SUCCESS".equals(result.get("result_code"))) {
    
    // Withdrawal succeeded 
    resultEnum = WithDrawEnum.fromText("SUCCESS");
    return resultEnum;
} else {
    
    // Withdrawal failed 
    resultEnum = WithDrawEnum.fromText(result.get("err_code"));
    throw new BadRequestException(resultEnum);
}

6、 Withdraw the enumeration class that returns the error code

@Getter
@NoArgsConstructor
@AllArgsConstructor
public enum WithDrawEnum {
    
	SUCCESS(0, " Withdrawal succeeded "),
	FAIL(400, " Withdrawal failed , The balance is less than the withdrawal amount "),
	HANDLE_FRE(5000, " Too often "),
	NO_AUTH(5001, " No permission for this interface "),
	AMOUNT_LIMIT(5002, " The amount exceeds the limit "),
	PARAM_ERROR(5003, " Parameter error "),
	OPENID_ERROR(5004, "Openid error "),
	SEND_FAILED(5005, " Payment error "),
	NOTENOUGH(5006, " Lack of balance "),
	SYSTEMERROR(5007, " The system is busy , Please try again later ."),
	NAME_MISMATCH(5008, " Name verification error "),
	SIGN_ERROR(5009, " Signature error "),
	XML_ERROR(5010, " Error sending content "),
	FATAL_ERROR(5011, " The two sending parameters are inconsistent "),
	FREQ_LIMIT(5012, " Frequency limit exceeded , Please try again later ."),
	MONEY_LIMIT(5013, " You have reached the upper limit of today's total payment / This payment limit has been reached "),
	CA_ERROR(5014, " Merchant certificate verification error "),
	V2_ACCOUNT_SIMPLE_BAN(5015, " Unable to pay users without real names "),
	PARAM_IS_NOT_UTF8(5016, " The sending parameter contains irregular characters "),
	SENDNUM_LIMIT(5017, " The number of payments made by this user today exceeds the limit ,  If necessary, please enter 【 WeChat payment merchant platform - Product center - Pay in change - Product settings 】 Make changes "),
	RECV_ACCOUNT_NOT_ALLOWED(5018, " The collection account is not in the collection account list "),
	PAY_CHANNEL_NOT_ALLOWED(5019, " This merchant ID is not configured with this function "),
	SEND_MONEY_LIMIT(5020, " The upper limit of today's merchant payment limit has been reached "),
	RECEIVED_MONEY_LIMIT(5021, " You have reached the limit of payment to this user today ");
	private int code;
	private String msg;

	public static WithDrawEnum fromText(String text) {
    
		if (text != null) {
    
			for (WithDrawEnum b : WithDrawEnum.values()) {
    
				if (text.equalsIgnoreCase(b.name())) {
    
					return b;
				}
			}
		}
		return null;
	}
}

Last

Call of wechat related interfaces , The main thing is to be patient with the instructions of the document , To achieve business needs .