微信分享生成自己的二维码

1.获取自己的appid和Secret

其中的appid和secret是项目的

public static String getAccessToken(String appid,String secret) throws Exception {

        String requestUrl = AccessToken_URL.replace("APPID",appid).replace("APPSECRET",secret);
        URL url = new URL(requestUrl);
       
        // 打开和URL之间的连接
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        
        // 设置通用的请求属性
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setRequestProperty("Connection", "Keep-Alive");
        connection.setUseCaches(false);
        connection.setDoOutput(true);
        connection.setDoInput(true);
        
        // 得到请求的输出流对象
        DataOutputStream out = new DataOutputStream(connection.getOutputStream());
        out.writeBytes("");
        out.flush();
        out.close();

        // 建立实际的连接
        connection.connect();
        // 定义 BufferedReader输入流来读取URL的响应
        BufferedReader in = null;
        if (requestUrl.contains("nlp")) {
            in = new BufferedReader(new InputStreamReader(connection.getInputStream(), "GBK"));
        }
        else {
            in = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));
        }
        String result = "";
        String getLine;
        while ((getLine = in.readLine()) != null) {
            result += getLine;
        }
        in.close();
        JSONObject jsonObject = JSON.parseObject(result);
        String accesstoken=jsonObject.getString("access_token");
        return accesstoken;
    }

2.根据以上生成的access token来生成二维码

public static String getQRCode(HttpServletResponse response,Object scene,String page)throws Exception {
            String property = System.getProperty("user.dir");
            String ctxPath = property;
            String fileName="twoCode.png";
            String bizPath = "img";
            String nowday = new SimpleDateFormat("yyyyMMdd").format(new Date());
            String ppath =ctxPath + File.separator + bizPath + File.separator + nowday;
            File file1 = new File(ctxPath + File.separator + bizPath + File.separator + nowday);
            if (!file1.exists()) {
                file1.mkdirs();// 创建文件根目录
            }
            String savePath = file1.getPath() + File.separator + fileName;
            String qrCode = bizPath + File.separator + nowday+ File.separator + fileName;
//        if (ppath.contains("\\")) {
//            ppath = ppath.replace("\\", "/");
//        }
            if (qrCode.contains("\\")) {
                qrCode = qrCode.replace("\\", "/");
            }

		/**
		在此输入自己的appid和Secret 
		**/
            String wxspAppid = "appid" ;
            //小程序的 app secret (在微信小程序管理后台获取)
            String wxspSecret = "Secret ";
            String accessToken = WxQrCode.getAccessToken(wxspAppid,wxspSecret);
            String wxCodeURL = "https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token="+accessToken;
            URL url = new URL(wxCodeURL);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.setRequestMethod("POST");// 提交模式
            // 发送POST请求必须设置如下两行
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream());
            // 发送请求参数
            JSONObject paramJson = new JSONObject();
            paramJson.put("scene", scene);
            paramJson.put("page", page); //小程序暂未发布我没有带page参数
            System.out.println(paramJson);
            printWriter.write(paramJson.toString());
            // flush输出流的缓冲
            printWriter.flush();
            //开始获取数据
            BufferedInputStream bis = new BufferedInputStream(httpURLConnection.getInputStream());
            OutputStream os = new FileOutputStream(new File(savePath));
            int len;
            byte[] arr = new byte[1024];
            while ((len = bis.read(arr)) != -1)
            {
                os.write(arr, 0, len);
                os.flush();
            }
            os.close();
            //实现了生成二维码并保存在本地电脑的硬盘中。
            File file = new File(savePath);
            FileInputStream fis = new FileInputStream(file);
            long size = file.length();
            byte[] temp = new byte[(int) size];
            fis.read(temp, 0, (int) size);
            fis.close();
            byte[] data = temp;
            response.setContentType("image/png");
            OutputStream out = response.getOutputStream();
            out.write(data);
            out.flush();
            out.close();
            }

3.总结

 String property = System.getProperty("user.dir");

1.以上是根据项目来获取根路径

2.二维码生成失败：

a：要不是你page路径小程序未上线或者是你传入的scene的参数不正确

item_id=118149&shop_id=249

这是正确的，scene最大32个可见字符长度有限，如果你传入的参数较多需要单独进行处理

b：读取的时候会报image = null 明明所在的文件有照片就是读取失败，这个问题可能是你读取照片的时候格式不同造成的，网上有好多解决办法

3.二维码生成了但是扫描后显示参数丢失，那就需要看看前端接收的时候是以什么格式接收的，以什么参数接收的，这就是scene的参数问题；