微信小程序 支付后台java实现实例

微信小程序 支付后台java实现实例

前言：

前些天使用 LeanCloud 云引擎写了个小程序的支付相关 以前只做过 APP 支付 这次在小程序支付爬了两天的坑 把代码也分享出来

支付流程:

1.小程序前端获取微信 openId 以及订单号 传给后台
2,后台根据 openId 和订单号进行签名 post 微信统一下单接口
3.后台获取微信返回的xml字符串 解析 二次签名以后返回给前端
4.前端调起支付微信支付 API

先看支付函数:

//获取支付信息
  @EngineFunction("getPayInformation")
  public static Map<String, Object> getPayInformation(
      @EngineFunctionParam("orderId") String orderId
  ) throws AVException, UnsupportedEncodingException, DocumentException {
    Map<String, Object> reqMap = new TreeMap<String, Object>(
        new Comparator<String>() {
          public int compare(String obj1, String obj2) {
            // 升序排序
            return obj1.compareTo(obj2);
          }
        });
    if (AVUser.getCurrentUser() != null) {
      String authDataJson = JSONArray.toJSONString(AVUser.getCurrentUser().get("authData"));
      JSONObject jsonObject = JSON.parseObject(authDataJson);
      jsonObject.get("lc_weapp");
      JSONObject j2 = JSON.parseObject(jsonObject.get("lc_weapp").toString());
      String openId = (String) j2.get("openid");

      AVQuery<Order> query = AVObject.getQuery(Order.class);
      Order order = query.get(orderId);
      reqMap.put("appid", System.getenv("appid"));
      reqMap.put("mch_id", System.getenv("mch_id"));
      reqMap.put("nonce_str", WXPayUtil.getNonce_str());
      reqMap.put("body", new String(order.getDishesList().toString().getBytes("UTF-8")));
      reqMap.put("openid", openId);
      reqMap.put("out_trade_no", order.getObjectId());
      reqMap.put("total_fee", 1); //订单总金额，单位为分
      reqMap.put("spbill_create_ip", "192.168.0.1"); //用户端ip
      reqMap.put("notify_url", System.getenv("notify_url")); //通知地址
      reqMap.put("trade_type", System.getenv("trade_type")); //trade_type=JSAPI时（即公众号支付），此参数必传，此参数为微信用户在商户对应appid下的唯一标识
      String reqStr = WXPayUtil.map2Xml(reqMap);
      String resultXml = HttpRequest.sendPost(reqStr);
      System.out.println("微信请求返回:" + resultXml);
      //解析微信返回串 如果状态成功 则返回给前端
      if (WXPayUtil.getReturnCode(resultXml) != null && WXPayUtil.getReturnCode(resultXml).equals("SUCCESS")) {
        //成功
        Map<String, Object> resultMap = new TreeMap<>(
            new Comparator<String>() {
              public int compare(String obj1, String obj2) {
                // 升序排序
                return obj1.compareTo(obj2);
              }
            });
        resultMap.put("appId", System.getenv("appid"));
        resultMap.put("nonceStr", WXPayUtil.getNonceStr(resultXml));//解析随机字符串
        resultMap.put("package", "prepay_id=" + WXPayUtil.getPrepayId(resultXml));
        resultMap.put("signType", "MD5");
        resultMap.put("timeStamp", String.valueOf((System.currentTimeMillis() / 1000)));//时间戳
        String paySign = WXPayUtil.getSign(resultMap);
        resultMap.put("paySign", paySign);
        return resultMap;
      } else {
        throw new AVException(999, "微信请求支付失败");
      }
    } else {
      throw new AVException(98, "当前未登录用户");
    }
  }

其中appid和mch_id可以用系统常量

PS:这里注意一个坑

二次签名的时候使用 appId nonceStr package signType timeStamp 这五个key生成签名(这里无视微信官方文档 以及注意 appId 的大小写)

前端调起API支付时 按照官方文档就可以

网络请求类:

HttpRequest

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;

public class HttpRequest {
  /**
   * 向指定URL发送GET方法的请求
   *
   * @param url  发送请求的URL
   * @param param 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
   * @return URL 所代表远程资源的响应结果
   */
  public static String sendGet(String url, String param) {
    String result = "";
    BufferedReader in = null;
    try {
      String urlNameString = url + "?" + param;
      URL realUrl = new URL(urlNameString);
      // 打开和URL之间的连接
      URLConnection connection = realUrl.openConnection();
      // 设置通用的请求属性
      connection.setRequestProperty("accept", "*/*");
      connection.setRequestProperty("connection", "Keep-Alive");
      connection.setRequestProperty("user-agent",
          "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
      // 建立实际的连接
      connection.connect();
      // 获取所有响应头字段
      Map<String, List<String>> map = connection.getHeaderFields();
      // 遍历所有的响应头字段
      for (String key : map.keySet()) {
        System.out.println(key + "--->" + map.get(key));
      }
      // 定义 BufferedReader输入流来读取URL的响应
      in = new BufferedReader(new InputStreamReader(
          connection.getInputStream()));
      String line;
      while ((line = in.readLine()) != null) {
        result += line;
      }
    } catch (Exception e) {
      System.out.println("发送GET请求出现异常！" + e);
      e.printStackTrace();
    }
    // 使用finally块来关闭输入流
    finally {
      try {
        if (in != null) {
          in.close();
        }
      } catch (Exception e2) {
        e2.printStackTrace();
      }
    }
    return result;
  }

  /**
   * 向指定 URL 发送POST方法的请求
   *
   * @param url  发送请求的 URL
   * @param param 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
   * @return 所代表远程资源的响应结果
   */
  public static String sendPost(String param) {
    PrintWriter out = null;
    BufferedReader in = null;
    String result = "";
    try {
      URL realUrl = new URL("https://api.mch.weixin.qq.com/pay/unifiedorder");
      // 打开和URL之间的连接
      URLConnection conn = realUrl.openConnection();
      // 设置通用的请求属性
      conn.setRequestProperty("accept", "*/*");
      conn.setRequestProperty("connection", "Keep-Alive");
      conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
//      conn.setRequestProperty("Pragma:", "no-cache");
//      conn.setRequestProperty("Cache-Control", "no-cache");
//      conn.setRequestProperty("Content-Type", "text/xml;charset=utf-8");
      // 发送POST请求必须设置如下两行
      conn.setDoOutput(true);
      conn.setDoInput(true);
      // 获取URLConnection对象对应的输出流
      out = new PrintWriter(conn.getOutputStream());
      // 发送请求参数
      out.print(param);
      // flush输出流的缓冲
      out.flush();
      // 定义BufferedReader输入流来读取URL的响应
      in = new BufferedReader(
          new InputStreamReader(conn.getInputStream()));
      String line;
      while ((line = in.readLine()) != null) {
        result += line;
      }
    } catch (Exception e) {
      System.out.println("发送 POST 请求出现异常！" + e);
      e.printStackTrace();
    }
    //使用finally块来关闭输出流、输入流
    finally {
      try {
        if (out != null) {
          out.close();
        }
        if (in != null) {
          in.close();
        }
      } catch (IOException ex) {
        ex.printStackTrace();
      }
    }
    return result;
  }
}

XML解析工具类

WXPayUtil

import org.w3c.dom.NodeList;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.Map;
import java.util.Random;

public class WXPayUtil {

  //生成随机字符串
  public static String getNonce_str() {
    String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    Random random = new Random();
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < 15; i++) {
      int number = random.nextInt(base.length());
      sb.append(base.charAt(number));
    }
    return sb.toString();
  }

  //map转xml 加上签名信息
  public static String map2Xml(Map<String, Object> map) throws UnsupportedEncodingException {
    StringBuffer sb = new StringBuffer();
    StringBuilder sb2 = new StringBuilder();
    sb2.append("<xml>");
    for (String key : map.keySet()) {
      sb.append(key);
      sb.append('=');
      sb.append(map.get(key));
      sb.append('&');
      // sb2是用来做请求的xml参数
      sb2.append("<" + key + ">");
//      sb2.append("<![CDATA[" + map.get(key) + "]]>");
      sb2.append(map.get(key));
      sb2.append("</" + key + ">");
    }
    sb.append(System.getenv("signKey"));
    String sign = MD5.getMessageDigest(sb.toString().getBytes()).toUpperCase();
    sb2.append("<sign>");
    sb2.append(sign);
    sb2.append("</sign>");
    sb2.append("</xml>");
    return sb2.toString();
  }

  //解析微信返回return_code SUCCESS或FILE
  //根据微信返回resultXml再次生成签名
  public static String getSign(Map<String, Object> map) {
    StringBuffer sb = new StringBuffer();
    for (String key : map.keySet()) {
      sb.append(key);
      sb.append('=');
      sb.append(map.get(key));
      sb.append('&');
    }
    sb.append(System.getenv("signKey"));
    System.out.println("第二次签名内容:" + sb);
    System.out.println("第二次签名SING:" + MD5.getMessageDigest(sb.toString().getBytes()).toUpperCase());
    return MD5.getMessageDigest(sb.toString().getBytes()).toUpperCase();
  }

  //解析微信返回return_code SUCCESS或FILE
  public static String getReturnCode(String resultXml) {
    String nonceStr;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder;
    try {
      builder = dbf.newDocumentBuilder();
      InputStream inputStream = new ByteArrayInputStream(resultXml.getBytes());
      org.w3c.dom.Document doc = builder.parse(inputStream); //
      // 下面开始读取
      org.w3c.dom.Element root = doc.getDocumentElement(); // 获取根元素
      NodeList nl = root.getElementsByTagName("return_code");
      org.w3c.dom.Element el = (org.w3c.dom.Element) nl.item(0);
      org.w3c.dom.Node nd = el.getFirstChild();
      nonceStr = nd.getNodeValue();
      return nonceStr;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

  //解析微信返回return_msg
  public static String getReturn_msg(String resultXml) {
    String nonceStr;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder;
    try {
      builder = dbf.newDocumentBuilder();
      InputStream inputStream = new ByteArrayInputStream(resultXml.getBytes());
      org.w3c.dom.Document doc = builder.parse(inputStream); //
      // 下面开始读取
      org.w3c.dom.Element root = doc.getDocumentElement(); // 获取根元素
      NodeList nl = root.getElementsByTagName("return_msg");
      org.w3c.dom.Element el = (org.w3c.dom.Element) nl.item(0);
      org.w3c.dom.Node nd = el.getFirstChild();
      nonceStr = nd.getNodeValue();
      return nonceStr;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

  //解析微信返回appid
  public static String getAppId(String resultXml) {
    String nonceStr;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder;
    try {
      builder = dbf.newDocumentBuilder();
      InputStream inputStream = new ByteArrayInputStream(resultXml.getBytes());
      org.w3c.dom.Document doc = builder.parse(inputStream); //
      // 下面开始读取
      org.w3c.dom.Element root = doc.getDocumentElement(); // 获取根元素
      NodeList nl = root.getElementsByTagName("appid");
      org.w3c.dom.Element el = (org.w3c.dom.Element) nl.item(0);
      org.w3c.dom.Node nd = el.getFirstChild();
      nonceStr = nd.getNodeValue();
      return nonceStr;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

  //解析微信返回mch_id
  public static String getMchId(String resultXml) {
    String nonceStr;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder;
    try {
      builder = dbf.newDocumentBuilder();
      InputStream inputStream = new ByteArrayInputStream(resultXml.getBytes());
      org.w3c.dom.Document doc = builder.parse(inputStream); //
      // 下面开始读取
      org.w3c.dom.Element root = doc.getDocumentElement(); // 获取根元素
      NodeList nl = root.getElementsByTagName("mch_id");
      org.w3c.dom.Element el = (org.w3c.dom.Element) nl.item(0);
      org.w3c.dom.Node nd = el.getFirstChild();
      nonceStr = nd.getNodeValue();
      return nonceStr;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

  //解析微信返回nonce_str
  public static String getNonceStr(String resultXml) {
    String nonceStr;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder;
    try {
      builder = dbf.newDocumentBuilder();
      InputStream inputStream = new ByteArrayInputStream(resultXml.getBytes());
      org.w3c.dom.Document doc = builder.parse(inputStream); //
      // 下面开始读取
      org.w3c.dom.Element root = doc.getDocumentElement(); // 获取根元素
      NodeList nl = root.getElementsByTagName("nonce_str");
      org.w3c.dom.Element el = (org.w3c.dom.Element) nl.item(0);
      org.w3c.dom.Node nd = el.getFirstChild();
      nonceStr = nd.getNodeValue();
      return nonceStr;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

  //解析微信返回prepay_id
  public static String getPrepayId(String resultXml) {
    String nonceStr;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder;
    try {
      builder = dbf.newDocumentBuilder();
      InputStream inputStream = new ByteArrayInputStream(resultXml.getBytes());
      org.w3c.dom.Document doc = builder.parse(inputStream); //
      // 下面开始读取
      org.w3c.dom.Element root = doc.getDocumentElement(); // 获取根元素
      NodeList nl = root.getElementsByTagName("prepay_id");
      org.w3c.dom.Element el = (org.w3c.dom.Element) nl.item(0);
      org.w3c.dom.Node nd = el.getFirstChild();
      nonceStr = nd.getNodeValue();
      return nonceStr;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

}

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