微信小程序支付+Java后台实现（完整版）

在开发微信小程序支付的功能前，我们先熟悉下微信小程序支付的业务流程图：

不熟悉流程的建议还是仔细阅读微信官方的开发者文档。

一，准备工作

事先需要申请企业版小程序，并开通“微信支付”（即商户功能）。并获取一下参数：

appid=********  //小程序appid
mchid=********  //小程序绑定商户id
key=*****************  //商户后台设置的key

并在商户后天设置开发者选项，主要是设置回调域名。

二，Java后台代码编写

Controller层代码：

@RestController
@RequestMapping(value = "/payment/")
public class PaymentController {

	private static Logger logger = LoggerFactory.getLogger(PaymentController.class);
	@Value("${hcc.wx.domain}")
	private String orderDomain;
	
	@Autowired
	private PaymentService paymentService;

     /**
	 * 
统一下单入口
	 *
	 * @param request
	 * @param response
	 * @throws Exception
	 */
	@ResponseBody
    @RequestMapping(value="toPay", method=RequestMethod.POST, 
produces ={"application/json;charset=UTF-8"})
	public JSONObject toPay(HttpServletRequest request) throws Exception {
		String requestStr = RequestStr.getRequestStr(request);
		if (StringUtils.isEmpty(requestStr)) {
			throw new ParamException();
		}
		JSONObject jsonObj = JSONObject.parseObject(requestStr);
		if(StringUtils.isEmpty(jsonObj.getString("orderNo")) || StringUtils.isEmpty(jsonObj.getString("openId"))){
		   	throw new ParamException();
		}
	   	OrderInfo orderInfo = .....//此处写获取订单信息方法
	   	if(orderInfo == null){
	   		return AjaxUtil.renderFailMsg("订单不存在！");
	   	}else if(orderInfo.getPayAmount() == null || orderInfo.getPayAmount() <= 0){
	   		return AjaxUtil.renderFailMsg("订单有误，请确认！");
	   	}else if(orderInfo.getOrderStatus() != 1){//1待付款
	   		String msg = orderInfo.getOrderStatus() >1 ?"此订单已支付！":"订单未提交，请确认！";
	   		return AjaxUtil.renderFailMsg(msg);
	   	}else{
	   		logger.info("【小程序支付服务】请求订单编号:["+orderInfo.getOrderNo()+"]");
		   	Map resMap = paymentService.xcxPayment(+orderInfo.getOrderNo(),orderInfo.getPayAmount(),jsonObj.getString("openId"));
		   	if("SUCCESS".equals(resMap.get("returnCode")) && "OK".equals(resMap.get("returnMsg"))){
		   		//统一下单成功
		   		resMap.remove("returnCode");
		   		resMap.remove("returnMsg");
		   		logger.info("【小程序支付服务】支付下单成功！");
		   		return AjaxUtil.renderSuccessMsg(resMap);
		   	}else{
		   		logger.info("【小程序支付服务】支付下单失败！原因:"+resMap.get("returnMsg"));
		   		return AjaxUtil.renderFailMsg(resMap.get("returnMsg"));
		   }
	   	}

	}
    /**
	 * 
回调Api
	 *
	 * @param request
	 * @param response
	 * @throws Exception
	 */
    @RequestMapping(value="xcxNotify")
	public void xcxNotify(HttpServletRequest request,HttpServletResponse response) throws Exception {
 		InputStream inputStream =  request.getInputStream();
 		//获取请求输入流
		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len=inputStream.read(buffer))!=-1){
            outputStream.write(buffer,0,len);
        }
        outputStream.close();
        inputStream.close();
        Map map = BeanToMap.getMapFromXML(new String(outputStream.toByteArray(),"utf-8"));
        logger.info("【小程序支付回调】 回调数据： \n"+map);
        String resXml = "";
        String returnCode = (String) map.get("return_code");
        if ("SUCCESS".equalsIgnoreCase(returnCode)) {
            String returnmsg = (String) map.get("result_code");
            if("SUCCESS".equals(returnmsg)){
            	//更新数据
            	int result = paymentService.xcxNotify(map);
            	if(result > 0){
	            	//支付成功
	                resXml = "" + ""
	                        + ""+"";
            	}
            }else{
                resXml = "" + ""
                        + "" + "";
                logger.info("支付失败:"+resXml);
            }
        }else{
            resXml = "" + ""
                    + "" + "";
            logger.info("【订单支付失败】");
        }
        
        logger.info("【小程序支付回调响应】 响应内容：\n"+resXml);
        response.getWriter().print(resXml);
	}
}

Service接口层代码（部分代码）：

/**
* 
支付接口层
* 
* @author att  
* @date 2018年5月27日
* @since jdk1.8
* @version 1.0
 */
public interface PaymentService {

	Map xcxPayment(String orderNo, double money,String openId) throws Exception;
	
	int xcxNotify(Map map) throws Exception;
}

Service接口实现（部分代码）：

@Service(value = "paymentService")
public class PaymentServiceImpl implements PaymentService{
	private static Logger LOGGER = LoggerFactory.getLogger(PaymentServiceImpl.class);
	
	@Value("${spring.profiles.active}")
	private String PROJECT_ENV;
	
	@Value("${hcc.wx.domain}")
	private String orderDomain;
	
	@Autowired
	private PaymentRecordMapper paymentRecordMapper;
	@Autowired
	private PaymentNotifyMapper paymentNotifyMapper;
	
	@Override
	public Map xcxPayment(String orderNum, double money,String openId) throws Exception {
		LOGGER.info("【小程序支付】 统一下单开始, 订单编号="+orderNum);
		SortedMap resultMap = new TreeMap();
		//生成支付金额，开发环境处理支付金额数到0.01、0.02、0.03元
		double payAmount = PayUtil.getPayAmountByEnv(PROJECT_ENV, money);
		//添加或更新支付记录(参数跟进自己业务需求添加)
		int flag = this.addOrUpdatePaymentRecord(orderNum, payAmount,.....);
		if(flag < 0){
			resultMap.put("returnCode", "FAIL");
			resultMap.put("returnMsg", "此订单已支付！");
			LOGGER.info("【小程序支付】 此订单已支付！");
		}else if(flag == 0){
			resultMap.put("returnCode", "FAIL");
			resultMap.put("returnMsg", "支付记录生成或更新失败！");
			LOGGER.info("【小程序支付】 支付记录生成或更新失败！");
		}else{
	        Map resMap = this.xcxUnifieldOrder(orderNum, PayConfig.TRADE_TYPE_JSAPI, payAmount,openId);
	        if(PayConstant.SUCCESS.equals(resMap.get("return_code")) && PayConstant.SUCCESS.equals(resMap.get("result_code"))){
	    		resultMap.put("appId", PayConfig.XCX_APP_ID);
	    		resultMap.put("timeStamp", PayUtil.getCurrentTimeStamp());
	    		resultMap.put("nonceStr", PayUtil.makeUUID(32));
	    		resultMap.put("package", "prepay_id="+resMap.get("prepay_id"));
	    		resultMap.put("signType", "MD5");
	    		resultMap.put("sign", PayUtil.createSign(resultMap,PayConfig.XCX_KEY));
	    		resultMap.put("returnCode", "SUCCESS");
	    		resultMap.put("returnMsg", "OK");
	    		LOGGER.info("【小程序支付】统一下单成功，返回参数:"+resultMap);
	        }else{
	        	resultMap.put("returnCode", resMap.get("return_code"));
	    		resultMap.put("returnMsg", resMap.get("return_msg"));
	    		LOGGER.info("【小程序支付】统一下单失败，失败原因:"+resMap.get("return_msg"));
	        }
		}
		return resultMap;
	}
	
	/**
	 * 小程序支付统一下单
	 */
	private Map xcxUnifieldOrder(String orderNum,String tradeType, double payAmount,String openid) throws Exception{
    	//封装参数
        SortedMap paramMap = new TreeMap();
        paramMap.put("appid", PayConfig.XCX_APP_ID);
        paramMap.put("mch_id", PayConfig.XCX_MCH_ID);
        paramMap.put("nonce_str", PayUtil.makeUUID(32));
        paramMap.put("body", BaseConstants.PLATFORM_COMPANY_NAME);
        paramMap.put("out_trade_no", orderNum);
        paramMap.put("total_fee", PayUtil.moneyToIntegerStr(payAmount));
        paramMap.put("spbill_create_ip", PayUtil.getLocalIp());
        paramMap.put("notify_url", this.getNotifyUrl());
        paramMap.put("trade_type", tradeType);
        paramMap.put("openid",openid);
        paramMap.put("sign", PayUtil.createSign(paramMap,PayConfig.XCX_KEY));
        //转换为xml
        String xmlData = PayUtil.mapToXml(paramMap);
        //请求微信后台，获取预支付ID
        String resXml = HttpUtils.postData(PayConfig.WX_PAY_UNIFIED_ORDER, xmlData);
        LOGGER.info("【小程序支付】 统一下单响应：\n"+resXml);
        return PayUtil.xmlStrToMap(resXml);
    }
	
	private String getNotifyUrl(){
		//服务域名
		return PayConfig.PRO_SERVER_DOMAIN + "/wxapp/payment/xcxNotify";
	}
	
	/**
	 * 添加或更新支付记录
	 */
	@Override
	public int addOrUpdatePaymentRecord(String orderNo, double payAmount,......) throws Exception{
		//写自己的添加或更新支付记录的业务代码
		return 0;
	}
	
	@Override
	@Transactional(readOnly=false,rollbackFor={Exception.class})
	public int xcxNotify(Map map) throws Exception{
        int flag = 0;
        //支付订单编号
        String orderNo = (String)map.get("out_trade_no");
        //检验是否需要再次回调刷新数据
        //TODO 微信后台回调，刷新订单支付状态等相关业务

        return flag;
	}

PayUtil工具类：

/**
 * Function: 支付工具类 

 * date: 2018-01-18 

 *
 * @author att
 * @version 1.0
 * @since JDK1.8
 * @see
 */
public class PayUtil {

	static Logger log = LogManager.getLogger(PayUtil.class.getName());
	/**
	 * 获取当前机器的ip
	 *
	 * @return String
	 */
	public static String getLocalIp(){
		InetAddress ia=null;
		String localip = null;
        try {
            ia=ia.getLocalHost();
            localip=ia.getHostAddress();
        } catch (Exception e) {
            e.printStackTrace();
        }
		return localip;
        
	}
	
	/**
	 * Map转换为 Xml
	 * 
	 * @param data
	 * @return Xml
	 * @throws Exception
	 */
	public static String mapToXml(SortedMap map) throws Exception {
        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
        //防止XXE攻击
        documentBuilderFactory.setXIncludeAware(false);
        documentBuilderFactory.setExpandEntityReferences(false);
        DocumentBuilder documentBuilder= documentBuilderFactory.newDocumentBuilder();
        org.w3c.dom.Document document = documentBuilder.newDocument();
        org.w3c.dom.Element root = document.createElement("xml");
        document.appendChild(root);
        for (String key: map.keySet()) {
            String value = map.get(key);
            if (value == null) {
                value = "";
            }
            value = value.trim();
            org.w3c.dom.Element filed = document.createElement(key);
            filed.appendChild(document.createTextNode(value));
            root.appendChild(filed);
        }
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer transformer = tf.newTransformer();
        DOMSource source = new DOMSource(document);
        transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        StringWriter writer = new StringWriter();
        StreamResult result = new StreamResult(writer);
        transformer.transform(source, result);
        String output = writer.getBuffer().toString();
        try {
            writer.close();
        }
        catch (Exception ex) {
        }
        return output;
    }

	
	/**
	 * 创建签名Sign
	 * 
	 * @param key
	 * @param parameters
	 * @return
	 */ 
	public static String createSign(SortedMap parameters,String key){  
        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();  
            if(entry.getValue() != null || !"".equals(entry.getValue())) {
            	String v = String.valueOf(entry.getValue());
            	if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
            		sb.append(k + "=" + v + "&");
            	}
            }  
        }  
        sb.append("key=" + key);  
        String sign = MD5Util.MD5Encode(sb.toString(), "UTF-8").toUpperCase();  
        return sign;  
    }
    
	
	/**
	 * XML转换为Map
	 * 
	 * @param strXML
	 * @return Map
	 * @throws Exception
	 */
	public static Map getMapFromXML(String strXML) throws Exception {
        try {
            Map data = new HashMap();
            DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
            //防止XXE攻击
            documentBuilderFactory.setXIncludeAware(false);
            documentBuilderFactory.setExpandEntityReferences(false);
            DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
            InputStream stream = new ByteArrayInputStream(strXML.getBytes("UTF-8"));
            org.w3c.dom.Document doc = documentBuilder.parse(stream);
            doc.getDocumentElement().normalize();
            NodeList nodeList = doc.getDocumentElement().getChildNodes();
            for (int idx = 0; idx < nodeList.getLength(); ++idx) {
                Node node = nodeList.item(idx);
                if (node.getNodeType() == Node.ELEMENT_NODE) {
                    org.w3c.dom.Element element = (org.w3c.dom.Element) node;
                    data.put(element.getNodeName(), element.getTextContent());
                }
            }
            try {
                stream.close();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
            return data;
        } catch (Exception ex) {
            throw ex;
        }
	}
    
	/**
	 * 生成随机数
	 * 
	 * @return
	 */
	public static String makeUUID(int len) {
		return UUID.randomUUID().toString().replaceAll("-", "").substring(0, len);
	}
	
	/**
     * 获取当前的Timestamp
     * 
     * @return
     */
    public static String getCurrentTimeStamp() {
        return Long.toString(System.currentTimeMillis()/1000);
    }

    /**
     * 获取当前的时间
     * @return
     */
    public static long getCurrentTimestampMs() {
        return System.currentTimeMillis();
    }
    
    /**
     * 生成订单号
     * 
     * @return
     */
    public static String generateOrderNo() {	
    	SimpleDateFormat sdf  = new SimpleDateFormat("yyMMdd");
        return sdf.format(new Date())+makeUUID(16);
    }
	
    /**
	 * 获取当前工程url
	 * 
	 * @param request
	 * @return
	 */
	public static String getCurrentUrl(HttpServletRequest request){
		return request.getScheme() +"://" + request.getServerName()  + ":" +request.getServerPort() +request.getContextPath();
	}
	
	/**
	 * Xml字符串转换为Map
	 * 
	 * @param xmlStr
	 * @return
	 */
	public static Map xmlStrToMap(String xmlStr){
        Map map = new HashMap();
        Document doc;
        try {
            doc = DocumentHelper.parseText(xmlStr);
            Element root = doc.getRootElement();
            List children = root.elements();
            if(children != null && children.size() > 0) {
                for(int i = 0; i < children.size(); i++) {
                    Element child = (Element)children.get(i);
                    map.put(child.getName(), child.getTextTrim());
                }
            }
        } catch (DocumentException e) {
            e.printStackTrace();
        }
        return map;
    }
	
	public static String getSceneInfo(String wapUrl,String name){
		Map> map = new HashMap>();
		if(!StringUtils.isEmpty(wapUrl) && !StringUtils.isEmpty(name)){
			/*{"h5_info": {"type":"Wap","wap_url": "https://pay.qq.com","wap_name": "腾讯充值"}}*/
			Map childmap = new TreeMap();
			childmap.put("type", "Wap");
			childmap.put("wap_url",wapUrl);
			childmap.put("wap_name", name);
			map.put("h5_info", childmap);
			return JSON.toJSONString(map);
		}
		return null;
	}
	

    /**
     * 转换金额型到整型
     * @param money
     * @return
     */
    public static String moneyToIntegerStr(Double money){
        BigDecimal decimal = new BigDecimal(money);
        int amount = decimal.multiply(new BigDecimal(100))
            .setScale(0, BigDecimal.ROUND_HALF_UP).intValue();
        return String.valueOf(amount);
    }

    /** 
     * 除去数组中的空值和签名参数
     * @param sArray 签名参数组
     * @return 去掉空值与签名参数后的新签名参数组
     */
    public static Map paraFilter(Map sArray) {

        Map result = new HashMap();

        if (sArray == null || sArray.size() <= 0) {
            return result;
        }

        for (String key : sArray.keySet()) {
            String value = sArray.get(key);
            if (value == null || value.equals("") || key.equalsIgnoreCase("sign")
                || key.equalsIgnoreCase("sign_type")) {
                continue;
            }
            result.put(key, value);
        }

        return result;
    }
    
    /** 
     * 把数组所有元素排序，并按照“参数=参数值”的模式用“&”字符拼接成字符串
     * @param params 需要排序并参与字符拼接的参数组
     * @return 拼接后字符串
     */
    public static String createLinkString(Map params) {
        List keys = new ArrayList(params.keySet());
        Collections.sort(keys);
        String prestr = "";
        for (int i = 0; i < keys.size(); i++) {
            String key = keys.get(i);
            String value = params.get(key);
            if (i == keys.size() - 1) {//拼接时，不包括最后一个&字符
                prestr = prestr + key + "=" + value;
            } else {
                prestr = prestr + key + "=" + value + "&";
            }
        }
        return prestr;
    }
    
    /**
     * 根据不同环境生成支付金额
     * 
     * @param env
     * @param money
     * @param payType
     * @return
     */
    public static double getPayAmountByEnv(String env,Double money){
    	double pay_money = 0.01;
    	//测试环境
    	if(BaseConstants.PLATFORM_ENV_DEV.equals(env)){
			if(money>10000){
				pay_money = 0.03;
			}else if(money>1000){
				pay_money = 0.02;
			}else{
				pay_money = 0.01;
			}
			return pay_money;
    	}else{
    		//生成环境
    		return money;
    	}
    }
}

支付配置类：

/**
 * Function: 支付配置 

 * date: 2018-01-18 

 *
 * @author att
 * @version 1.0
 * @since JDK1.8
 */
public class PayConfig {

	//微信支付类型
	//NATIVE--原生支付
	//JSAPI--公众号支付-小程序支付
	//MWEB--H5支付
	//APP -- app支付
	public static final String TRADE_TYPE_NATIVE = "NATIVE";
	public static final String TRADE_TYPE_JSAPI = "JSAPI";
	public static final String TRADE_TYPE_MWEB = "MWEB";
	public static final String TRADE_TYPE_APP = "APP";
			
	//小程序支付参数
	public static String XCX_APP_ID;
	public static String XCX_MCH_ID;
	public static String XCX_KEY;
	
	//微信支付API
	public static final String WX_PAY_UNIFIED_ORDER = "https://api.mch.weixin.qq.com/pay/unifiedorder";
	
	//参数
	static{
		Properties properties = new Properties();
		try {
			properties.load(PayConstant.class.getClassLoader().getResourceAsStream("payment_config.properties"));
            //xcx
            XCX_APP_ID=(String) properties.get("xcx.pay.appid");
            XCX_MCH_ID=(String) properties.get("xcx.pay.mchid");
            XCX_KEY=(String) properties.get("xcx.pay.key");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

Properties配置：

##config
xcx.pay.appid=wx**********
xcx.pay.mchid=*****
xcx.pay.key=**********

三，小程序端（获取统一下单返回参数发起支付）

在小程序端，发起支付请求到，Java后台的统一下单接口返回prepay_id等参数，然后封装调起微信的js方法：wx.requestPayment(OBJECT)，具体参考文档：官方文档

测试一把：

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