微信公众号支付开发Demo

微信官方文档
建议大家先看下流程图：

大概的流程是先获取openid –>统一下单 –> 返回预支付交易会话标识 prepay_id等参数 –>然后返回页面h5调用微信支付的页面

获取openid

代码如下:

package com.shine.house.controller;

import com.alibaba.fastjson.JSONObject;
import com.github.wxpay.sdk.WXPay;
import com.github.wxpay.sdk.WXPayConstants;
import com.github.wxpay.sdk.WXPayUtil;
import com.shine.house.util.Constants;
import com.shine.house.util.HttpUtil;
import com.shine.house.util.IpUtil;
import com.shine.house.util.MyConfig;
import com.shine.house.util.OnlyId;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

@Controller
public class WxPayController {

    /**
     * @Description : 前往微信获取openId
     * @Author : 高冷的美男子
     * @Date : Created in 8:52 2018/5/25
     */
    @RequestMapping(value = {
  
  "/toGetOpenID", "/"})
    public void toWeChat(HttpServletRequest request, HttpServletResponse response) throws Exception {

        //第一步：用户同意授权，获取code,会重定向到backUrl
        String url = "https://open.weixin.qq.com/connect/oauth2/authorize?appid=" + Constants.APP_ID
                + "&redirect_uri=" + URLEncoder.encode(Constants.BACKURL)
                + "&response_type=code"
                + "&scope=snsapi_base"
                + "&state=STATE#wechat_redirect";
        response.sendRedirect(url);
    }


    /**
     * 微信网页授权获得微信详情
     *
     * @param code
     * @param state
     * @throws ServletException
     * @throws IOException
     */
    @RequestMapping("/getOpenInfo")
    public String getOpenInfo(HttpServletRequest request, HttpServletResponse response, Model model) throws Exception {

                 String code=request.getParameter("code");

             if(code==null) {
                 System.out.println("未获取到微信授权，返回参数如下：");
                         Map<String, String[]> params=request.getParameterMap();
                         for (Entry<String, String[]> entry: params.entrySet()) {
                                            System.out.println("key:"+entry.getKey()+" Value:"+entry.getValue());
                                        }
                 return "wepay";
             }
            //用户同意
            JSONObject result = getAccess_token(code);
            if (result.get("errcode") == null) {
                //成功  返回到首页
                String openid = (String) result.get("openid");
                String access_token = (String) result.get("access_token");
                HttpSession session = request.getSession();
                session.setAttribute("openid", openid);
                session.setAttribute("access_token", access_token);
                if (openid==null){
                    model.addAttribute("errmsg","openid为空");
                }
                if (access_token==null){
                    model.addAttribute("errmsg","access_token为空");
                }
                System.out.println("openid:"+openid);
                return "wepay";
            } else {
                //失败
                model.addAttribute("errmsg","获取openid失败，请重新尝试");
            }



        return "wepay";
    }

    /**
     * @Description : 统一下单
     * @Author : 高冷的美男子
     * @Date : Created in 9:20 2018/5/25
     */              
    @RequestMapping("/unifiedOrder")
    public String unifiedOrder(@RequestParam("total_fee") Double total_fee,HttpServletRequest request,Model model) throws Exception {
       HttpSession session=request.getSession();
        String spbill_create_ip=IpUtil.getIp(request);
        //统一下单
        MyConfig config = new MyConfig();
        WXPay wxpay = new WXPay(config);
        Map<String, String> data = new HashMap<String, String>();
        //商品描述
        data.put("body", "test充钱");
        //商户订单号
        data.put("out_trade_no", OnlyId.getOnlyOrderNo());
         int fee=(int) (total_fee*100);
        //标价金额  付款金额
        data.put("total_fee", String.valueOf(fee));
        //客户终端IP
        data.put("spbill_create_ip", spbill_create_ip);
        //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。
        data.put("notify_url", Constants.NOTIFY_URL);
        //交易类型  公众号支付
        data.put("trade_type", "JSAPI");
        //用户标识
        data.put("openid",(String) session.getAttribute("openid"));


        Map<String, String> resp=null;
        try {

           resp = wxpay.unifiedOrder(data);
           for (Entry<String, String> entry: resp.entrySet()) {
                System.out.println("key:"+entry.getKey()+" Value:"+entry.getValue());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        if (resp.get("return_code").equals("SUCCESS")){
        if (resp.get("result_code").equals("SUCCESS")){
            Map<String, String> Param = new HashMap<String, String>();
            Param.put("appId", Constants.APP_ID);
            Param.put("timeStamp", String.valueOf(System.currentTimeMillis() / 1000));
            Param.put("nonceStr", WXPayUtil.generateNonceStr());
            Param.put("package", "prepay_id=" + resp.get("prepay_id"));
            Param.put("signType", Constants.SIGN_TYPE);
            String sign=WXPayUtil.generateSignature(Param,config.getKey(),WXPayConstants.SignType.MD5);
            Param.put("paySign",sign);
                      model.addAttribute(