QR code generation of wechat applet with parameters

Use scenarios ： Scan the generated applet code , Open the applet and adjust it to the specified page with parameters , For example, the purchase details page .

Usage method ： Generate by calling the QR code interface of wechat applet .

Interface document ：https://developers.weixin.qq.com/miniprogram/dev/api/qrcode.html

It can be seen from the document that , There are three ways to get the QR code of an applet , Let's take the method B For example , Method B It is suitable for business scenarios with a large number of codes .

The generator interface is shown in the figure ：

Core code ：

/// <summary>
    ///  adopt POST Get the applet code 
    /// </summary>
    /// <param name="access_token"></param>
    /// <param name="scene"> Parameters carried </param>
    /// <param name="page"> Jump page </param>
    private void GetQRCode(string access_token, string scene, string page)
    {
        string formUrl = "https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token=" + access_token;

        string formData = "{\"scene\":\"" + scene + "\",\"page\":\"" + page + "\"}";

        // Pay attention to the submitted code   This side needs to be changed   The default here is Default： Current system code 
        byte[] postData = System.Text.Encoding.UTF8.GetBytes(formData);

        //  Set parameters related to submission  
        System.Net.HttpWebRequest request = System.Net.WebRequest.Create(formUrl) as System.Net.HttpWebRequest;
        System.Text.Encoding myEncoding = System.Text.Encoding.UTF8;
        request.Method = "POST";
        request.KeepAlive = false;
        request.AllowAutoRedirect = true;
        request.ContentType = "application/x-www-form-urlencoded";
        request.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727; .NET CLR  3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)";
        request.ContentLength = postData.Length;

        //  Submit request data  
        System.IO.Stream outputStream = request.GetRequestStream();
        outputStream.Write(postData, 0, postData.Length);
        outputStream.Close();

        System.Net.HttpWebResponse response;
        System.IO.Stream responseStream;
        response = request.GetResponse() as System.Net.HttpWebResponse;
        responseStream = response.GetResponseStream();
        BuildQRCode(responseStream);
    }

Show / Save image code ：

/// <summary>
    ///  Create a picture 
    /// </summary>
    /// <param name="stream"></param>
    private void BuildQRCode(System.IO.Stream stream)
    {
        System.IO.MemoryStream outstream = new System.IO.MemoryStream();
        const int bufferLen = 1024;
        byte[] buffer = new byte[bufferLen];
        int count = 0;
        while ((count = stream.Read(buffer, 0, bufferLen)) > 0)
        {
            outstream.Write(buffer, 0, count);
        }

         Save to local disk 
        //System.Drawing.Image img = System.Drawing.Image.FromStream(outstream);
        //img.Save(@"C:\2019\05\wx001.jpg");

        // Direct output picture 
        Response.ClearContent();
        Response.ContentType = "image/Png";
        Response.BinaryWrite(outstream.ToArray());
    }

The attachment ： Demo source code download