初试微信公众号支付

因为业务的需求，需要在微信内置的网页实现支付功能。微信提供的文档：https://pay.weixin.qq.com/index.php/core/home/login?return_url=%2F。

通过综合考虑，选择公众号支付方式。 

第一步：需要本身的公众号去申请开通微信支付。

第二步：微信本身提供的开发文档 https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=7_1，按照文档中的开发步骤，进行配置。

第三步：首先需要在后台实现统一下单接口，

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Scope;
import com.util.Constants;
import com.util.IdcardUtils;
import com.util.IpAddr;
import com.util.WxPayUtil;
import net.sf.json.JSONObject;

String requestUrl = "https://api.mch.weixin.qq.com/pay/unifiedorder";
appid = "";
  mch_id =Constants.MCH_ID;//微信公众号开通支付功能会有对应的商户号
  nonce_str = WxPayUtil.generateNonceStr();
body = planName;
out_trade_no = WxPayUtil.getCurrentTimestamp()+"";
total_fee = premium;
String spbill_create_ip = IpAddr.GetIpAddr();
String notify_url=""; //异步接收微信支付结果通知的回调地址，通知url必须为外网可访问的url，不能携带参数。
trade_type="JSAPI";
String openid = "";
Map<String, String> signMap = new HashMap();
signMap.put("appid", appid);
signMap.put("body", body);
signMap.put("mch_id", mch_id);
signMap.put("nonce_str", nonce_str);
signMap.put("notify_url", notify_url);
signMap.put("openid", openid);
signMap.put("out_trade_no", out_trade_no);
signMap.put("spbill_create_ip", spbill_create_ip);
signMap.put("total_fee", total_fee+"");
signMap.put("trade_type", trade_type);
key = Constants.TK_PARNTER_KEY;
sign = WxPayUtil.generateSignature(signMap,key);
signMap.put("sign", sign);
String mapXml = WxPayUtil.mapToXml(signMap);//注意以上参数的顺序不能有差错
//boolean mapRes = WxPayUtil.isSignatureValid(mapXml, key);
URL httpUrl = new URL(requestUrl);
HttpURLConnection httpURLConnection = (HttpURLConnection) httpUrl.openConnection();
httpURLConnection.setRequestProperty("Host", "api.mch.weixin.qq.com");
httpURLConnection.setDoOutput(true);
    httpURLConnection.setRequestMethod("POST");
httpURLConnection.setConnectTimeout(10*1000);
  httpURLConnection.setReadTimeout(10*1000);
    httpURLConnection.connect();
  OutputStream outputStream = httpURLConnection.getOutputStream();
        outputStream.write(mapXml.getBytes("UTF-8"));
        //获取内容
        InputStream inputStream = httpURLConnection.getInputStream();
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
        final StringBuffer stringBuffer = new StringBuffer();
        String line = null;
        while ((line = bufferedReader.readLine()) != null) {
            stringBuffer.append(line);
        }
        String resp = stringBuffer.toString();
        Syst em.out.println(resp);
        if (stringBuffer!=null) {
            try {
                bufferedReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (inputStream!=null) {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (outputStream!=null) {
            try {
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        Map<String,String> result = WxPayUtil.xmlToMap(resp);
        String return_code = result.get("return_code");
        String return_msg = result.get("return_msg");
        String result_code = result.get("result_code");
        if(!"SUCCESS".equals(return_code)||!"SUCCESS".equals(result_code)){
        msg=return_msg;
        //return "success";
        }
        prepay_id = result.get("prepay_id");
        appid = result.get("appid");
        nonce_str = result.get("nonce_str");
        sign = result.get("sign");
        Long timeStampL = WxPayUtil.getCurrentTimestamp();
        timeStamp = timeStampL.toString();
        Map<String,String> twoSign = new HashMap<String, String>();
        twoSign.put("appId", appid);
        twoSign.put("timeStamp", timeStamp);
        twoSign.put("nonceStr", nonce_str);
        twoSign.put("package", "prepay_id="+prepay_id);
        twoSign.put("signType", "MD5");
        sign2 = WxPayUtil.generateSignature(twoSign, key);
return "success";

中间用到的一些工具包，微信均有提供（https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=11_1）。

第四步，如果成功的话会返回prepared_id,接下来实现前段页面，只需要在前段页面已有的逻辑代码上加上

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(result);
        }

function onBridgeReady(result){
      var appId = result.appid;
      var timeStamp=result.timeStamp;
      var nonceStr = result.nonce_str;
      var prepay_id = result.prepay_id;
      var paySign = result.sign2;
      WeixinJSBridge.invoke(
          'getBrandWCPayRequest',{
        "appId": appId,
        "timeStamp":timeStamp,
        "nonceStr":nonceStr,
        "package":"prepay_id="+prepay_id,
        "signType":"MD5",
        "paySign":paySign
          },
          function(res){     
              if(res.err_msg == "get_brand_wcpay_request:ok" ) {
              }else{
            alert("支付失败"); 
              }     // 使用以上方式判断前端返回,微信团队郑重提示：res.err_msg将在用户支付成功后返回    ok，但并不保证它绝对可靠。 
          }
      ); 
    }
   

以上就是我实现微信公众号支付的过程，初次尝试，还请路过的大神提出改进；