②准备好11个参数 JSAPI支付方式

1 配置微信平台

①配置微信公众平台

登录微信公众平台=》公众号设置=》功能设置=》网页授权域名

②配置微信商家平台

①先去官方下载SDK，并导进项目中

2 后台代码的实现

JSAPI官方文档：

①先去官方下载SDK，并导进项目中

地址：

②准备好11个参数

 appid：商家平台ID。在微信的平台上有

body：商品描述。

mch_id：商户ID。在微信的平台上有

nonce_str：随机字符串，UUID就好了。

openid：用户标识。因为这边是用户已经登录成功了。所以在session中就能拿到。

out_trade_no：商户订单号

spbill_create_ip：终端IP。这个可以从请求头中拿到

total_fee：支付金额。单位是分。

trade_type：交易类型。这里我填JSAPI

notify_url：通知地址。就是用户支付成功之后，微信访问你的哪个接口，跟你传递支付成功的相关信息。  

sign：签名。这个签名它是由上面的10个参数计算得出的。

③源码
sendPay类：

 import java.io.IOException;
import java.io.InputStream;
import java.math.BigDecimal;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.http.auth.AUTH;
import org.hamcrest.core.Is;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.jc.util.wxPay.WXPayUtil;
import com.sun.xml.internal.fastinfoset.Encoder;

import controller.AuthUtil;
import net.sf.json.JSONObject;

@Controller
@RequestMapping("/pay")
public class sendPay {
 
    /**
     * @Description 微信浏览器内微信支付/公众号支付(JSAPI)
     * @param request
     * @param code
     * @return Map
     */
    @RequestMapping(value = "orders")
    public @ResponseBody Map<String, String> orders(HttpServletRequest request, HttpServletResponse response) {
        try {
             
            String openId = "用户的openid";

            // 拼接统一下单地址参数
            Map<String, String> paraMap = new HashMap<String, String>();
            // 获取请求ip地址
            String ip = request.getHeader("x-forwarded-for");
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getHeader("Proxy-Client-IP");
            }
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getHeader("WL-Proxy-Client-IP");
            }
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
                ip = request.getRemoteAddr();
            }
            if (ip.indexOf(",") != -1) {
                String[] ips = ip.split(",");
                ip = ips[0].trim();
            }

            paraMap.put("appid", AuthUtil.APPID); // 商家平台ID
            paraMap.put("body", "纯情小店铺-薯条"); // 商家名称-销售商品类目、String(128)
            paraMap.put("mch_id", AuthUtil.MCHID); // 商户ID
            paraMap.put("nonce_str", WXPayUtil.generateNonceStr()); // UUID
            paraMap.put("openid", openId);
            paraMap.put("out_trade_no", UUID.randomUUID().toString().replaceAll("-", ""));// 订单号,每次都不同
            paraMap.put("spbill_create_ip", ip);
            paraMap.put("total_fee", "1"); // 支付金额，单位分
            paraMap.put("trade_type", "JSAPI"); // 支付类型
            paraMap.put("notify_url", "用户支付完成后，你想微信调你的哪个接口");// 此路径是微信服务器调用支付结果通知路径随意写
            String sign = WXPayUtil.generateSignature(paraMap, AuthUtil.PATERNERKEY);
            paraMap.put("sign", sign);
            String xml = WXPayUtil.mapToXml(paraMap);// 将所有参数(map)转xml格式

            // 统一下单 
            String unifiedorder_url = "#34;;

            System.out.println("xml为：" + xml);

            // String xmlStr = HttpRequest.sendPost(unifiedorder_url,
            // xml);//发送post请求"统一下单接口"返回预支付id:prepay_id

            String xmlStr = HttpRequest.httpsRequest(unifiedorder_url, "POST", xml);

            System.out.println("xmlStr为：" + xmlStr);

            // 以下内容是返回前端页面的json数据
            String prepay_id = "";// 预支付id
            if (xmlStr.indexOf("SUCCESS") != -1) {
                Map<String, String> map = WXPayUtil.xmlToMap(xmlStr);
                prepay_id = (String) map.get("prepay_id");
            }

            Map<String, String> payMap = new HashMap<String, String>();
            payMap.put("appId", AuthUtil.APPID);
            payMap.put("timeStamp", WXPayUtil.getCurrentTimestamp() + "");
            payMap.put("nonceStr", WXPayUtil.generateNonceStr());
            payMap.put("signType", "MD5");
            payMap.put("package", "prepay_id=" + prepay_id);
            String paySign = WXPayUtil.generateSignature(payMap, AuthUtil.PATERNERKEY);
            payMap.put("paySign", paySign);
            //将这个6个参数传给前端
            return payMap;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * @Title: callBack
     * @Description: 支付完成的回调函数
     * @param:
     * @return:
     */
    @RequestMapping("/notify")
    public String callBack(HttpServletRequest request, HttpServletResponse response) {
        // System.out.println("微信支付成功,微信发送的callback信息,请注意修改订单信息");
        InputStream is = null;
        try {

            is = request.getInputStream();// 获取请求的流信息(这里是微信发的xml格式所有只能使用流来读)
            String xml = WXPayUtil.InputStream2String(is);
            Map<String, String> notifyMap = WXPayUtil.xmlToMap(xml);// 将微信发的xml转map
            
            System.out.println("微信返回给回调函数的信息为："+xml);
            
            if (notifyMap.get("result_code").equals("SUCCESS")) {
                String ordersSn = notifyMap.get("out_trade_no");// 商户订单号
                String amountpaid = notifyMap.get("total_fee");// 实际支付的订单金额:单位 分
                BigDecimal amountPay = (new BigDecimal(amountpaid).divide(new BigDecimal("100"))).setScale(2);// 将分转换成元-实际支付金额:元

                /*
                 * 以下是自己的业务处理------仅做参考 更新order对应字段/已支付金额/状态码
                 */
                System.out.println("===notify===回调方法已经被调！！！");
                
            }
            
            // 告诉微信服务器收到信息了，不要在调用回调action了========这里很重要回复微信服务器信息用流发送一个xml即可
            response.getWriter().write("<xml><return_code><![CDATA[SUCCESS]]></return_code></xml>");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) { 
                    e.printStackTrace();
                }
            }
        }
        
        return null;
    }

}  

HttpRequest类：

 import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;

public class HttpRequest {
    /**
     * 向指定URL发送GET方法的请求
     * 
     * @param url
     *            发送请求的URL
     * @param param
     *            请求参数,请求参数应该是 name1=value1&name2=value2 的形式。
     * @return URL 所代表远程资源的响应结果
     */
    public static String sendGet(String url, String param) {
        String result = "";
        BufferedReader in = null;
        try {
            String urlNameString = url + "?" + param;
            System.out.println(urlNameString);
            URL realUrl = new URL(urlNameString);
            // 打开和URL之间的连接
            URLConnection connection = realUrl.openConnection();
            // 设置通用的请求属性
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 建立实际的连接
            connection.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍历所有的响应头字段
            for (String key : map.keySet()) {
                System.out.println(key + "--->" + map.get(key));
            }
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 向指定 URL 发送POST方法的请求
     * 
     * @param url
     *            发送请求的 URL
     * @param param
     *            请求参数,请求参数应该是 name1=value1&name2=value2 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, String param) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            // 发送请求参数
            out.print(param);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }

    /**
     * post请求并得到返回结果
     * 
     * @param requestUrl
     * @param requestMethod
     * @param output
     * @return
     */
    public static String httpsRequest(String requestUrl, String requestMethod, String output) {
        try { 
            URL url = new URL(requestUrl);
            HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setUseCaches(false);
            connection.setRequestMethod(requestMethod);
            if (null != output) {
                OutputStream outputStream = connection.getOutputStream();
                outputStream.write(output.getBytes("UTF-8"));
                outputStream.close();
            }
            // 从输入流读取返回内容
            InputStream inputStream = connection.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String str = null;
            StringBuffer buffer = new StringBuffer();
            while ((str = bufferedReader.readLine()) != null) {
                buffer.append(str);
            }
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();
            inputStream = null;
            connection.disconnect();
            return buffer.toString();
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return "";
    }
}  

AuthUtil类

 import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import net.sf.json.JSONObject;
public class AuthUtil {
    public static final String APPID = "平台ID";
    public static final String APPSECRET = "平台密钥";
    public static final String MCHID = "商家ID";
    public static final String PATERNERKEY = "商家密钥";
    
    
    public static JSONObject doGetJson(String url) throws ClientProtocolException, IOException {
        JSONObject jsonObject = null;
        // 首先初始化HttpClient对象
        DefaultHttpClient client = new DefaultHttpClient();
        // 通过get方式进行提交
        HttpGet httpGet = new HttpGet(url);
        // 通过HTTPclient的execute方法进行发送请求
        HttpResponse response = client.execute(httpGet);
        // 从response里面拿自己想要的结果
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            String result = EntityUtils.toString(entity, "UTF-8");
            jsonObject = jsonObject.fromObject(result);
        }
        // 把链接释放掉
        httpGet.releaseConnection();
        return jsonObject;
    }
}  

2.3 前端的实现

这是只用一个jsp页面来做测试

 <%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "#34;>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="./js/jquery-1.11.0.min.js"></script>
<title>微信支付JSP</title>
</head>
<body> 
    <input type="button" value="进行微信支付" id="payId">

    <script type="text/javascript">
    
        $(function(){
            var appId,timeStamp,nonceStr,package,signType,paySign; 
            
            $("#payId").click(function(){
                pay();
            });
            
            //去后台拿六个参数
            function pay(){   
                var url = "#34;;
                  $.get(url,function(result) {    
                          appId = result.appId;
                        timeStamp = result.timeStamp;
                        nonceStr = result.nonceStr;
                        package = result.package;
                        signType = result.signType;
                        paySign = result.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);
                            }
                            alert("请在微信上进行支付操作！");
                            onBridgeReady();
                        } else { 
                            onBridgeReady();
                        }
                    });
                }
            //去微信那边发起支付请求
            function onBridgeReady(){
                
                 alert("appId:"+appId+" "+"timeStamp:"+timeStamp+" "+"nonceStr:"+nonceStr+" "+"package:"+package+" "+"signType:"+signType+" "+"paySign:"+paySign+" ");
                
                  WeixinJSBridge.invoke( 'getBrandWCPayRequest', {
                      "appId":appId,     //公众号名称,由商户传入     
                      "timeStamp":timeStamp,         //时间戳,自1970年以来的秒数     
                      "nonceStr":nonceStr, //随机串     
                      "package":package,     
                      "signType":signType,         //微信签名方式：     
                      "paySign":paySign //微信签名 
                     }, 
                     function(res){      
                         if(res.err_msg == "get_brand_wcpay_request:ok" ) {
                             //alert('支付成功');
                             console.log("支付成功");
                             //支付成功后跳转的页面
                         }else if(res.err_msg == "get_brand_wcpay_request:cancel"){
                             alert('支付取消');
                         }else if(res.err_msg == "get_brand_wcpay_request:fail"){
                             alert('支付失败');
                             
                             alert(JSON.stringify(res));
                             
                             WeixinJSBridge.call('closeWindow');
                         } //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。
               });    
            }
        })
</script>

</body>
</html>  

三，总结

虽然第一次看官方文档很乱，信息量很多，但仔细总结一下，其实就下面这点流程而已。

再记录点，以防有用：

url urlencode

 public static String inputStream2String(InputStream inStream, String encoding){
        String result = null;
        ByteArrayOutputStream outStream = null;
        try {
         if(inStream != null){
          outStream = new ByteArrayOutputStream();
          byte[] tempBytes = new byte[1024];
          int count = 0;
          while((count = inStream.read(tempBytes)) != -1){
           outStream.write(tempBytes, 0, count);
          }
          tempBytes = null;
          outStream.flush();
          result = new String(outStream.toByteArray(), encoding);
          outStream.close();
         }
        } catch (Exception e) {
         result = null;
        } 
        return result;
       }  

转载：