【JAVA笔记】JAVA后端实现统一扫码支付：微信篇
最近做完了一个项目，正好没事做，产品经理就给我安排了一个任务。
做一个像收钱吧这样可以统一扫码收钱的功能。
一开始并不知道是怎么实现的，咨询了好几个朋友，才知道大概的业务流程：先是开一个网页用来判断支付平台，是微信还是支付宝，判断过后就好办了，直接照搬微信支付和支付宝的官方文档。不过微信的文档感觉有点坑，得多花点心思。
现在讲讲怎么实现微信支付网页支付，也就是公众号支付：
1.判断支付平台，在判断是微信平台时，必须使用window.location打开网页，使用其他方法在IOS版微信无法打开网页，至少现在的新版微信无法打开。对应的连接是请求获取code的链接。第2步会讲到。
<html> <head> <title>判断客户平台</title> <basefont face="微软雅黑" size="2" /> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> <meta name="exporter-version" content="Evernote Windows/303244 (zh-CN, DDL); Windows/6.1.7601 Service Pack 1 (Win64);"/> <script type="text/javascript" src="jquery-3.1.1.min.js"></script> <style> body, td { font-family: 微软雅黑; font-size: 10pt; } </style> </head> <body> <script type="text/javascript"> window.onload = function(){ if(isWeiXin()){ window.location='http://www.xxoo.com/InterfaceAPI/code'; } else if(isZFB()){ alert('支付宝即将开放....'); //var p = document.getElementsByTagName('p'); //p[0].innerHTML = window.navigator.userAgent; }else{ alert('请使用微信或者支付宝App扫码'); } } function isWeiXin(){ var ua = window.navigator.userAgent.toLowerCase(); if(ua.match(/MicroMessenger/i) == 'micromessenger'){ return true; }else{ return false; } } function isZFB(){ var ua = window.navigator.userAgent.toLowerCase(); if(ua.match(/AlipayClient/i) =='alipayclient'){ return true; }else{ return false; } } </script> </body></html>
2.这里是获取code，回调地址必须使用URLEncoder的utf-8编码，这里最终只获取openid，需要获取UserInfo其他信息的自行测试，只需要修改一下 scope 的参数，
@RequestMapping({ "code" })
public void getCode(HttpServletRequest request, HttpServletResponse response) {
try {
//回调地址
String redirect_uri = URLEncoder.encode(
"http://www.xxoo.com/InterfaceAPI/openid?codeID=7837283",
"utf-8");
String url = "https://open.weixin.qq.com/connect/oauth2/authorize?appid="
+ WechatConfig.APP_ID
+ "&redirect_uri="
+ redirect_uri
+ "&response_type=code&scope=snsapi_base&state=STATE#wechat_redirect";
response.sendRedirect(url);
} catch (Exception e) {
e.printStackTrace();
}
}
3.里面有一个codeid的参数，不要在意这个，是用来测试用的。这里只需要openid,下面是使用get方法获取json返回结果，获取到openid后，重定向到支付页面。
@RequestMapping({ "openid" })
public void getOpenid(String codeID, String code,
HttpServletResponse response) {
try {
String requestUrl = "https://api.weixin.qq.com/sns/oauth2/access_token?appid="
+ WechatConfig.APP_ID
+ "&secret="
+ WechatConfig.APP_SECRET
+ "&code="
+ code
+ "&grant_type=authorization_code";
if (code != null) {
String json = WebUtils.get(requestUrl, null);
WechatResult result = new Gson().fromJson(json,
WechatResult.class);
OPEN_ID = result.getOpenid();
System.out.println("====OPEN_ID====" + OPEN_ID);
response.sendRedirect("http://www.xxoo.com/InterfaceAPI/pay.html");
}
} catch (Exception e) {
e.printStackTrace();
}
}
4.在前端支付页面输入要支付的金额，提交到后台
$.ajax({ type: "POST", dataType: "html", url: "http://www.xxoo.com/InterfaceAPI/weixinPay", data: "value="+self.input.value, timeout:10000, cache: true, async: true, error: function(data){ //alert(data+"---value-->"+self.input.value); }, },});
5.后端获取金额然后在后端统一下单，公众号支付有两个地方不一样，一是支付类型要改为 JSAPI，二是需要获取openid
@RequestMapping({ "weixinPay" })
public void weixinPay(HttpServletRequest request,
HttpServletResponse response) {
String value = request.getParameter("value");
WechatTradeTest wechat = new WechatTradeTest();
String json = wechat.testunifiedOrder(Integer.valueOf(value), OPEN_ID);
//这里返回json到前端
write(json, response);
}
6.统一下单成功后返回的结果例子：
<xml> <return_code><![CDATA[SUCCESS]]></return_code> <return_msg><![CDATA[OK]]></return_msg> <appid><![CDATA[wx2421b1c4370ec43b]]></appid> <mch_id><![CDATA[10000100]]></mch_id> <nonce_str><![CDATA[IITRi8Iabbblz1Jc]]></nonce_str> <openid><![CDATA[oUpF8uMuAJO_M2pxb1Q9zNjWeS6o]]></openid> <sign><![CDATA[7921E432F65EB8ED0CE9755F0E86D72F]]></sign> <result_code><![CDATA[SUCCESS]]></result_code> <prepay_id><![CDATA[wx201411101639507cbf6ffd8b0779950874]]></prepay_id> <trade_type><![CDATA[JSAPI]]></trade_type> </xml>
7.返回的参数需要重新签名并返回到前端，签名方法与统一下单时的签名是一样的！签名时必须要带上微信商户返回是以Json格式返回到前端。
public String testunifiedOrder(int fee,String openid) { WechatUnifiedOrder request = new WechatUnifiedOrder(); request.setBody("测试商品"); request.setDetail("一个好商品"); request.setGoods_tag("测试"); request.setOut_trade_no(System.currentTimeMillis() + ""); request.setFee_type("CNY"); request.setTotal_fee(1); request.setSpbill_create_ip("192.168.88.26"); request.setTime_start(System.currentTimeMillis() + ""); request.setOpenid(openid); //下单成功后返回 WechatUnifiedOrder.Response response = WechatConfig.getInstance() .unifiedOrder(request); response.setTime_start(request.getTime_start()); WeichatData data = new WeichatData(); data.setAppId(response.getAppid()); data.setTimeStamp(request.getTime_start()); data.setNonceStr(response.getNonce_str()); data.setPrepay_id(response.getPrepay_id()); data.setSignType("MD5"); TreeMap<String, String> requestMap = new TreeMap<String, String>(); requestMap.put("appId", response.getAppid()); requestMap.put("timeStamp", response.getTime_start()); requestMap.put("nonceStr", response.getNonce_str()); requestMap.put("package", "prepay_id="+response.getPrepay_id()); requestMap.put("signType","MD5"); data.setPaySign(sign(requestMap).toUpperCase()); return new Gson().toJson(data); }
8.前端需要解析json，获取对应的值，唤醒微信支付
success: function(data){ if(data!=null){ var obj=eval("("+data+")"); appId = obj["appId"]; //timeStamp = new Date().getTime(); timeStamp = obj["timeStamp"]; nonceStr = obj["nonceStr"]; package = obj["prepay_id"]; paySign = obj["paySign"]; if (typeof WeixinJSBridge == "undefined"){ if( document.addEventListener ){ document.addEventListener('WeixinJSBridgeReady', onBridgeReady, false); }else if (document.attachEvent){ document.attachEvent('WeixinJSBridgeReady', onBridgeReady); document.attachEvent('onWeixinJSBridgeReady', onBridgeReady); } }else{ onBridgeReady(); } }else{ alert("支付失败"); } },
//微信回调 function onBridgeReady(){ WeixinJSBridge.invoke( 'getBrandWCPayRequest', { "appId" :appId, "timeStamp":timeStamp, "nonceStr" :nonceStr, "package" :"prepay_id="+package, "signType" :"MD5", "paySign" : paySign }, function(res){ if(res.err_msg == "get_brand_wcpay_request：ok" ) { }else { } } );
到这里基本成功了，同时感谢一位网友的文章：http://blog.csdn.net/u012706811/article/details/52988782。
