这里本篇文章使用java进行小程序后端编写，由于公司前段时间要做小程序支付，所以这里把自己写的小程序后端支付controller记录下来，文档参考微信支付官方文档，地址：https://pay.weixin.qq.com/wiki/doc/api/wxa/wxa_api.php?chapter=7_3&index=1。
推荐课程：Java教程。
废话不多说，直接上代码：
PayController
@Api(tags = "支付模块")
@RestController
@RequestMapping("")
public class PayController {
@ApiOperation(value = "请求支付接口")
@RequestMapping(value = "/wxPay", method = RequestMethod.POST)
public JSONObject wxPay(HttpServletRequest request) { try { //生成的随机字符串
String nonce_str = getRandomStringByLength(32); //商品名称
String body = "测试商品名称"; //获取客户端的ip地址
String spbill_create_ip = getIpAddr(request); //组装参数，用户生成统一下单接口的签名
Map packageParams = new HashMap<>();
packageParams.put("appid", WechatConfig.appid);
packageParams.put("mch_id", WechatConfig.mch_id);
packageParams.put("nonce_str", nonce_str);
packageParams.put("body", body);
packageParams.put("out_trade_no", payOrderId + "");//商户订单号,自己的订单ID
packageParams.put("total_fee", 100 + "");//支付金额，这边需要转成字符串类型，否则后面的签名会失败
packageParams.put("spbill_create_ip", spbill_create_ip);
packageParams.put("notify_url", WechatConfig.notify_url);//支付成功后的回调地址
packageParams.put("trade_type", WechatConfig.TRADETYPE);//支付方式
packageParams.put("openid", openId + "");//用户的openID，自己获取
String prestr = PayUtil.createLinkString(packageParams); // 把数组所有元素，按照“参数=参数值”的模式用“&”字符拼接成字符串
//MD5运算生成签名，这里是第一次签名，用于调用统一下单接口
String mysign = PayUtil.sign(prestr, WechatConfig.key, "utf-8").toUpperCase(); //拼接统一下单接口使用的xml数据，要将上一步生成的签名一起拼接进去
String xml = "" + "" + WechatConfig.appid + " "
+ ""
+ "" + WechatConfig.mch_id + " "
+ "" + nonce_str + " "
+ "" + WechatConfig.notify_url + " "
+ "" + openid + " "
+ "" + payOrderId + " "
+ "" + spbill_create_ip + " "
+ "" + 100 + " "//支付的金额，单位：分
+ "" + WechatConfig.TRADETYPE + " "
+ "" + mysign + " "
+ " "; //调用统一下单接口，并接受返回的结果
String result = PayUtil.httpRequest(WechatConfig.pay_url, "POST", xml); // 将解析结果存储在HashMap中
Map map = PayUtil.doXMLParse(result); String return_code = (String) map.get("return_code");//返回状态码
String result_code = (String) map.get("result_code");//返回状态码
Map response = new HashMap();//返回给小程序端需要的参数
if (return_code == "SUCCESS" && return_code.equals(result_code)) { String prepay_id = (String) map.get("prepay_id");//返回的预付单信息
response.put("nonceStr", nonce_str);
response.put("package", "prepay_id=" + prepay_id);
Long timeStamp = System.currentTimeMillis() / 1000;
response.put("timeStamp", timeStamp + "");//这边要将返回的时间戳转化成字符串，不然小程序端调用wx.requestPayment方法会报签名错误
//拼接签名需要的参数
String stringSignTemp = "appId=" + WechatConfig.appid + "&nonceStr=" + nonce_str + "&package=prepay_id=" + prepay_id + "&signType=MD5&timeStamp=" + timeStamp; //再次签名，这个签名用于小程序端调用wx.requesetPayment方法
String paySign = PayUtil.sign(stringSignTemp, WechatConfig.key, "utf-8").toUpperCase();
response.put("paySign", paySign);
}
response.put("appid", WechatConfig.appid); return Response.succ(response);
} catch (Exception e) {
e.printStackTrace();
} return null;
} //这里是支付回调接口，微信支付成功后会自动调用
@RequestMapping(value = "/wxNotify", method = RequestMethod.POST)
public void wxNotify(HttpServletRequest request, HttpServletResponse response) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream())); String line = null;
StringBuilder sb = new StringBuilder(); while ((line = br.readLine()) != null) {
sb.append(line);
}
br.close(); //sb为微信返回的xml
String notityXml = sb.toString(); String resXml = ""; Map map = PayUtil.doXMLParse(notityXml); String returnCode = (String) map.get("return_code"); if ("SUCCESS".equals(returnCode)) { //验证签名是否正确
Map validParams = PayUtil.paraFilter(map); //回调验签时需要去除sign和空值参数
String prestr = PayUtil.createLinkString(validParams);
//根据微信官网的介绍，此处不仅对回调的参数进行验签，还需要对返回的金额与系统订单的金额进行比对等
if (PayUtil.verify(prestr, (String) map.get("sign"), WechatConfig.key, "utf-8")) { /**此处添加自己的业务逻辑代码start**/
//注意要判断微信支付重复回调，支付成功后微信会重复的进行回调
/**此处添加自己的业务逻辑代码end**/
//通知微信服务器已经支付成功
resXml = "" + " ";
}
} else {
resXml = "" + " ";
}
BufferedOutputStream out = new BufferedOutputStream(
response.getOutputStream());
out.write(resXml.getBytes());
out.flush();
out.close();
} //获取随机字符串
private String getRandomStringByLength(int length) { String base = "abcdefghijklmnopqrstuvwxyz0123456789";
Random random = new Random();
StringBuffer sb = new StringBuffer(); for (int i = 0; i < length; i++) {
int number = random.nextInt(base.length());
sb.append(base.charAt(number));
} return sb.toString();
} //获取IP
private String getIpAddr(HttpServletRequest request) { String ip = request.getHeader("X-Forwarded-For"); if (StringUtils.isNotEmpty(ip) && !"unKnown".equalsIgnoreCase(ip)) { //多次反向代理后会有多个ip值，第一个ip才是真实ip
int index = ip.indexOf(","); if (index != -1) { return ip.substring(0, index);
} else { return ip;
}
}
ip = request.getHeader("X-Real-IP"); if (StringUtils.isNotEmpty(ip) && !"unKnown".equalsIgnoreCase(ip)) { return ip;
} return request.getRemoteAddr();
}
} 上面代码用到了PayUtil和WechatConfig这两个类，一个是配置类，一个是工具类，代码如下：
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PayUtil
public class PayUtil { /**
* 签名字符串
*
* @param text 需要签名的字符串
* @param key 密钥
* @param input_charset 编码格式
* @return 签名结果
*/
public static String sign(String text, String key, String input_charset) {
text = text + "&key=" + key; return DigestUtils.md5Hex(getContentBytes(text, input_charset));
} /**
* 签名字符串
*
* @param text 需要签名的字符串
* @param sign 签名结果
* @param key 密钥
* @param input_charset 编码格式
* @return 签名结果
*/
public static boolean verify(String text, String sign, String key, String input_charset) {
text = text + key; String mysign = DigestUtils.md5Hex(getContentBytes(text, input_charset)); if (mysign.equals(sign)) { return true;
} else { return false;
}
} /**
* @param content
* @param charset
* @return
* @throws java.security.SignatureException
* @throws UnsupportedEncodingException
*/
public static byte[] getContentBytes(String content, String charset) { if (charset == null || "".equals(charset)) { return content.getBytes();
} try { return content.getBytes(charset);
} catch (UnsupportedEncodingException e) { throw new RuntimeException("MD5签名过程中出现错误,指定的编码集不对,您目前指定的编码集是:" + charset);
}
}
private static boolean isValidChar(char ch) { if ((ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) return true; if ((ch >= 0x4e00 && ch <= 0x7fff) || (ch >= 0x8000 && ch <= 0x952f)) return true;// 简体中文汉字编码
return false;
} /**
* 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;
} /**
* @param requestUrl 请求地址
* @param requestMethod 请求方法
* @param outputStr 参数
*/
public static String httpRequest(String requestUrl, String requestMethod, String outputStr) { // 创建SSLContext
StringBuffer buffer = null; try {
URL url = new URL(requestUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod(requestMethod);
conn.setDoOutput(true);
conn.setDoInput(true);
conn.connect(); //往服务器端写内容
if (null != outputStr) {
OutputStream os = conn.getOutputStream();
os.write(outputStr.getBytes("utf-8"));
os.close();
} // 读取服务器端返回的内容
InputStream is = conn.getInputStream();
InputStreamReader isr = new InputStreamReader(is, "utf-8");
BufferedReader br = new BufferedReader(isr);
buffer = new StringBuffer(); String line = null; while ((line = br.readLine()) != null) {
buffer.append(line);
}
br.close();
} catch (Exception e) {
e.printStackTrace();
} return buffer.toString();
}
public static String urlEncodeUTF8(String source) { String result = source; try {
result = java.net.URLEncoder.encode(source, "UTF-8");
} catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block
e.printStackTrace();
} return result;
} /**
* 解析xml,返回第一级元素键值对。如果第一级元素有子节点，则此节点的值是子节点的xml数据。
*
* @param strxml
* @return
* @throws org.jdom2.JDOMException
* @throws IOException
*/
public static Map doXMLParse(String strxml) throws Exception { if (null == strxml || "".equals(strxml)) { return null;
} Map m = new HashMap();
InputStream in = String2Inputstream(strxml);
SAXBuilder builder = new SAXBuilder();
Document doc = builder.build(in);
Element root = doc.getRootElement();
List list = root.getChildren();
Iterator it = list.iterator(); while (it.hasNext()) {
Element e = (Element) it.next(); String k = e.getName(); String v = "";
List children = e.getChildren(); if (children.isEmpty()) {
v = e.getTextNormalize();
} else {
v = getChildrenText(children);
}
m.put(k, v);
} //关闭流
in.close(); return m;
} /**
* 获取子结点的xml
*
* @param children
* @return String
*/
public static String getChildrenText(List children) {
StringBuffer sb = new StringBuffer(); if (!children.isEmpty()) {
Iterator it = children.iterator(); while (it.hasNext()) {
Element e = (Element) it.next(); String name = e.getName(); String value = e.getTextNormalize();
List list = e.getChildren();
sb.append("<" + name + ">"); if (!list.isEmpty()) {
sb.append(getChildrenText(list));
}
sb.append(value);
sb.append("");
}
} return sb.toString();
}
public static InputStream String2Inputstream(String str) { return new ByteArrayInputStream(str.getBytes());
}
} WechatConfig
public class WechatConfig { //小程序appid
public static final String appid = ""; //微信支付的商户id
public static final String mch_id = ""; //微信支付的商户密钥
public static final String key = ""; //支付成功后的服务器回调url，这里填PayController里的回调函数地址
public static final String notify_url = ""; //签名方式，固定值
public static final String SIGNTYPE = "MD5"; //交易类型，小程序支付的固定值为JSAPI
public static final String TRADETYPE = "JSAPI"; //微信统一下单接口地址
public static final String pay_url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
}在刚刚开始接触小程序支付的时候，也觉得比较的棘手，因为自己并没有写过支付相关的代码。后来通过百度查找资料和阅读官方文档，最后把这个支付的controller完成了。最后，一定要多读几遍官方文档，然后结合PayController的代码去看，就会发现其实支付也不是很难。
