简介：微信小程序支付这里的坑还是有的，所以提醒各位在编写的一定要注意！！！
1.首先呢，你需要准备openid，appid，还有申请微信支付后要设置一个32位的密钥，需要先生成一个sign，得到prepay_id，然后再得到一个paySign，总之就是很墨迹，下面献上我的controller
//微信下单支付
@ResponseBody
@RequestMapping("doOrder")
public void doOrder(HttpServletRequest request, HttpServletResponse response) throws IOException, JDOMException {
request.setCharacterEncoding("UTF-8");
response.setCharacterEncoding("UTF-8");
//得到openid
String openid = request.getParameter("openid");
int fee = 0;
//得到小程序传过来的价格，注意这里的价格必须为整数，1代表1分，所以传过来的值必须*100；
if (null != request.getParameter("price")) {
fee = Integer.parseInt(request.getParameter("price").toString());
}
System.out.println(request.getParameter("price"));
System.out.println(fee);
//订单编号
String did = request.getParameter("did");
//订单标题
String title = request.getParameter("title");
//时间戳
String times = System.currentTimeMillis() + "";
SortedMap<Object, Object> packageParams = new TreeMap<Object, Object>();
packageParams.put("appid", "wxa**********2e2");
packageParams.put("mch_id", "1486425722");
packageParams.put("nonce_str", times);//时间戳
packageParams.put("body", title);//支付主体
packageParams.put("out_trade_no", did);//编号
packageParams.put("total_fee", fee);//价格
// packageParams.put("spbill_create_ip", getIp2(request));这里之前加了ip，但是总是获取sign失败，原因不明，之后就注释掉了
packageParams.put("notify_url", base+"/notify");//支付返回地址，不用纠结这个东西，我就是随便写了一个接口，内容什么都没有
packageParams.put("trade_type", "JSAPI");//这个api有，固定的
packageParams.put("openid", openid);//openid
//获取sign
String sign = PayCommonUtil.createSign("UTF-8", packageParams, "x********************************4");//最后这个是自己设置的32位密钥
packageParams.put("sign", sign);
//转成XML
String requestXML = PayCommonUtil.getRequestXml(packageParams);
System.out.println(requestXML);
//得到含有prepay_id的XML
String resXml = HttpUtil.postData("https://api.mch.weixin.qq.com/pay/unifiedorder", requestXML);
System.out.println(resXml);
//解析XML存入Map
Map map = XMLUtil.doXMLParse(resXml);
System.out.println(map);
// String return_code = (String) map.get("return_code");
//得到prepay_id
String prepay_id = (String) map.get("prepay_id");
SortedMap<Object, Object> packageP = new TreeMap<Object, Object>();
packageP.put("appId", "wxa**********2e2");//！！！注意，这里是appId,上面是appid，真怀疑写这个东西的人。。。
packageP.put("nonceStr", times);//时间戳
packageP.put("package", "prepay_id=" + prepay_id);//必须把package写成 "prepay_id="+prepay_id这种形式
packageP.put("signType", "MD5");//paySign加密
packageP.put("timeStamp", (System.currentTimeMillis() / 1000) + "");
//得到paySign
String paySign = PayCommonUtil.createSign("UTF-8", packageP, "x********************************4");
packageP.put("paySign", paySign);
//将packageP数据返回给小程序
Gson gson = new Gson();
String json = gson.toJson(packageP);
PrintWriter pw = response.getWriter();
System.out.println(json);
pw.write(json);
pw.close();
}123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566
2.下面是需要用到的工具类
（1）.生成sign以及得到sign后生成XML工具类PayCommonUtil
public class PayCommonUtil {
/**
* 是否签名正确,规则是:按参数名称a-z排序,遇到空值的参数不参加签名。
* @return boolean
*/
public static boolean isTenpaySign(String characterEncoding, SortedMap<Object, Object> packageParams, String API_KEY) {
StringBuffer sb = new StringBuffer();
Set es = packageParams.entrySet();
Iterator it = es.iterator();
while(it.hasNext()) {
Map.Entry entry = (Map.Entry)it.next();
String k = (String)entry.getKey();
String v = (String)entry.getValue();
if(!"sign".equals(k) && null != v && !"".equals(v)) {
sb.append(k + "=" + v + "&");
}
}
sb.append("key=" + API_KEY);
//算出摘要
String mysign = MD5.MD5Encode(sb.toString(), characterEncoding).toLowerCase();
String tenpaySign = ((String)packageParams.get("sign")).toLowerCase();
//System.out.println(tenpaySign + " " + mysign);
return tenpaySign.equals(mysign);
}
/**
* @author
* @Description：sign签名
* @param characterEncoding
* 编码格式
* @param parameters
* 请求参数
* @return
*/
public static String createSign(String characterEncoding, SortedMap<Object, Object> packageParams, String API_KEY) {
StringBuffer sb = new StringBuffer();
Set es = packageParams.entrySet();
Iterator it = es.iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
String k = entry.getKey().toString();
String v = entry.getValue().toString();
if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
sb.append(k + "=" + v + "&");
}
}
sb.append("key=" + API_KEY);
String sign = MD5.MD5Encode(sb.toString(), characterEncoding).toUpperCase();
return sign;
}
/**
* @author
* @Description：将请求参数转换为xml格式的string
* @param parameters
* 请求参数
* @return
*/
public static String getRequestXml(SortedMap<Object, Object> parameters) {
StringBuffer sb = new StringBuffer();
sb.append("<xml>");
Set es = parameters.entrySet();
Iterator it = es.iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
String k = entry.getKey().toString();
String v = entry.getValue().toString();
if ("attach".equalsIgnoreCase(k) || "body".equalsIgnoreCase(k) || "sign".equalsIgnoreCase(k)) {
sb.append("<" + k + ">" + "<![CDATA[" + v + "]]></" + k + ">");
} else {
sb.append("<" + k + ">" + v + "</" + k + ">");
}
}
sb.append("</xml>");
return sb.toString();
}
/**
* 取出一个指定长度大小的随机正整数.
*
* @param length
* int 设定所取出随机数的长度。length小于11
* @return int 返回生成的随机数。
*/
public static int buildRandom(int length) {
int num = 1;
double random = Math.random();
if (random < 0.1) {
random = random + 0.1;
}
for (int i = 0; i < length; i++) {
num = num * 10;
}
return (int) ((random * num));
}
/**
* 获取当前时间 yyyyMMddHHmmss
*
* @return String
*/
public static String getCurrTime() {
Date now = new Date();
SimpleDateFormat outFormat = new SimpleDateFormat("yyyyMMddHHmmss");
String s = outFormat.format(now);
return s;
}
}123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111
（2）.访问官方接口得到含有prepay_id的XML工具类HttpUtil
public class HttpUtil {
//private static final Log logger = Logs.get();
private final static int CONNECT_TIMEOUT = 5000; // in milliseconds
private final static String DEFAULT_ENCODING = "UTF-8";
public static String postData(String urlStr, String data){
return postData(urlStr, data, null);
}
public static String postData(String urlStr, String data, String contentType){
BufferedReader reader = null;
try {
URL url = new URL(urlStr);
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
conn.setConnectTimeout(CONNECT_TIMEOUT);
conn.setReadTimeout(CONNECT_TIMEOUT);
if(contentType != null)
conn.setRequestProperty("content-type", contentType);
OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream(), DEFAULT_ENCODING);
if(data == null)
data = "";
writer.write(data);
writer.flush();
writer.close();
reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), DEFAULT_ENCODING));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line);
sb.append("\r\n");
}
return sb.toString();
} catch (IOException e) {
//logger.error("Error connecting to " + urlStr + ": " + e.getMessage());
} finally {
try {
if (reader != null)
reader.close();
} catch (IOException e) {
}
}
return null;
}
}12345678910111213141516171819202122232425262728293031323334353637383940414243444546
（3）.解析XML工具类
public class XMLUtil {
public static Map doXMLParse(String strxml) throws JDOMException, IOException {
strxml = strxml.replaceFirst("encoding=\".*\"", "encoding=\"UTF-8\"");
if(null == strxml || "".equals(strxml)) {
return null;
}
Map m = new HashMap();
InputStream in = new ByteArrayInputStream(strxml.getBytes("UTF-8"));
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 = XMLUtil.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(XMLUtil.getChildrenText(list));
}
sb.append(value);
sb.append("</" + name + ">");
}
}
return sb.toString();
}
}1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162
（4）.MD5加密工具类
public class MD5 { private static String byteArrayToHexString(byte b[]) {
StringBuffer resultSb = new StringBuffer(); for (int i = 0; i < b.length; i++)
resultSb.append(byteToHexString(b[i])); return resultSb.toString();
} private static String byteToHexString(byte b) { int n = b; if (n < 0)
n += 256; int d1 = n / 16; int d2 = n % 16; return hexDigits[d1] + hexDigits[d2];
} public static String MD5Encode(String origin, String charsetname) {
String resultString = null; try {
resultString = new String(origin);
MessageDigest md = MessageDigest.getInstance("MD5"); if (charsetname == null || "".equals(charsetname))
resultString = byteArrayToHexString(md.digest(resultString
.getBytes())); else
resultString = byteArrayToHexString(md.digest(resultString
.getBytes(charsetname)));
} catch (Exception exception) {
} return resultString;
} private static final String hexDigits[] = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
}1234567891011121314151617181920212223242526272829303132333435363738
3.小程序支付函数
gopay: function () { var that = this
wx.request({
url: app.baseurl + \'doOrder\', data: { \'openid\': wx.getStorageSync(\'openids\'), \'title\': that.data.title, \'did\': that.data.did, \'price\': that.data.price*100
},
method: \'POST\', header: { "content-type": \'application/x-www-form-urlencoded\'
},
success: function (res) {
console.log(res.data)
console.log(res.data.timeStamp)
console.log(res.data.nonceStr)
console.log(res.data.package)
console.log(res.data.paySign)
wx.requestPayment({
timeStamp: res.data.timeStamp,
nonceStr: res.data.nonceStr,
package: res.data.package,
signType: res.data.signType,
paySign: res.data.paySign,
success: function (res) {
wx.request({
url: app.baseurl+\'updateState\', data: { \'did\': that.data.did,
},
method: \'GET\',
success:function(res){
console.log(res.data) if(res.data==1){
wx.redirectTo({
url: \'../orderDetial/orderDetial?did=\' + that.data.did,
})
}
}
})
},
fail: function (res) {
console.log(res)
}
})
}
})
}123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051
结束啦，小程序支付的java后台就这些。
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