How to generate sun code for WeChat applet in Java

Implementation plan

We can achieve the mini program sun code generation through the following method.

Generate restricted sun code

Implementation steps

• Get the access_token of the mini program

• Set path and with related parameters

• Call the getwxacodeunlimit interface and store the returned image locally

Get the small Program access_token

public static String getAccessToken(String appid, String appsecret)
    {
        String requestUrl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid="+appid+"&secret="+appsecret+"";
        String accessToken = null;
        try
        {
            String response = HttpClientUtil.getInstance().sendHttpsGet(
                    requestUrl, null);
            JSONObject json = JSONObject.parseObject(response);
            accessToken = String.valueOf(json.get("access_token"));
        }
        catch (Exception e)
        {
            logger.error("getAccessToken error", e);
        }

        return accessToken;
    }

Description: Just call the WeChat API interface and pass in the appid and appsecret parameters of the mini program.

Call WeChat api to generate mini program sun code

 public static String generatLimitSunCode(WxScanCodeParam param) throws Exception 
    {
       String token =param.getAccessToken();
       Map<String, String> params = new HashMap<>();
       params.put("path", param.getPath());
       params.put("width", "430");
       CloseableHttpClient httpClient = HttpClientBuilder.create().build();
       HttpPost httpPost = new HttpPost("https://api.weixin.qq.com/wxa/getwxacode?access_token="+token);
       httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");
       String body = JSON.toJSONString(params);
       StringEntity entity = new StringEntity(body);
       entity.setContentType("image/jpg");
       httpPost.setEntity(entity);
       HttpResponse response = httpClient.execute(httpPost);
       int statusCode = response.getStatusLine().getStatusCode();
       if (statusCode == HttpStatus.SC_OK) 
       {
           HttpEntity entity2 = response.getEntity();
           if(!entity2.getContentType().getValue().equals("image/jpeg"))
           {
               String result = EntityUtils.toString(entity2, "UTF-8");
               logger.error("generate sun code error,http execute result:" + result);
               return null;
           }
       }
       else
       {
           logger.error("generate sun code error,http execute result:" + statusCode);
       }
       
       InputStream inputStream = response.getEntity().getContent();
        // 保存图片到本地     
       int flag = saveImg(inputStream, param.getFilePath(), name);
       if (flag == 0)
       {
           throw new SysException("保存图片[" + name + "]失败");
       }
       else
       {
           logger.info("太阳码[{}]生成成功", name);
       }
       return param.getFilePath() + File.separatorChar + name;
   }

Description

Parameter description

• path: Scan the QR code to enter the mini program Page path, maximum length 128 bytes, cannot be empty; for example: pages/index/index

• access_token: Mini program authorization token

Note

Special attention needs to be paid. The total number of mini-program sun codes and QR codes generated by this solution cannot exceed 100,000. WeChat does not provide the corresponding API interface to query the usage quantity. Once the quantity is exceeded, This will cause the mini program to become invalid, and WeChat currently cannot reset the number of queries, which is suitable for scenarios where the number of generated is small.

Generate unlimited sun code

Get the access_token of the mini program

Same as the first solution

Call WeChat api to generate the mini program sun code

/**
     * 生成无限制的小程序码
     * @param param
     * @return
     * @throws Exception
     */
    public static String generatUnlimitSunCode(WxScanCodeParam param) throws Exception 
    {
       String token =param.getAccessToken();
       Map<String, String> params = new HashMap<>();
       params.put("scene", param.getScene());
       params.put("page", param.getPath());
       params.put("width", "430");
       CloseableHttpClient httpClient = HttpClientBuilder.create().build();
       HttpPost httpPost = new HttpPost("https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token="+token);
       httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");
       String body = JSON.toJSONString(params);
       StringEntity entity = new StringEntity(body);
       entity.setContentType("image/jpg");
       httpPost.setEntity(entity);
       HttpResponse response = httpClient.execute(httpPost);
       int statusCode = response.getStatusLine().getStatusCode();
       if (statusCode == HttpStatus.SC_OK) 
       {
           HttpEntity entity2 = response.getEntity();
           if(!entity2.getContentType().getValue().equals("image/jpeg"))
           {
               String result = EntityUtils.toString(entity2, "UTF-8");
               logger.error("generate sun code error,http execute result:" + result);
               return null;
           }
       }
       else
       {
           logger.error("generate sun code error,http execute result:" + statusCode);
       }
       
       InputStream inputStream = response.getEntity().getContent();
       
       //太阳码写标题
       String content=param.getWriteContent();
       if(StringUtil.isNotEmpty(content) && param.isWrite())
       {
          inputStream = ImageUtil.addImageTitle(param.getWriteContent(), inputStream, 450, 450);
       }
      
       String name = param.getFileName()+".jpg";//文件名加后缀，跟上面对应
       

       int flag = saveImg(inputStream, param.getFilePath(), name);// 保存图片
       if (flag == 0)
       {
           throw new SysException("保存图片[" + name + "]失败");
       }
       else
       {
           logger.info("太阳码[{}]生成成功", name);
       }
       return param.getFilePath() + File.separatorChar + name;
   }

Description

Parameter description

• scene: up to 32 visible characters, the parameter format can be defined by yourself a&b or a=1&b=2

• access_token: Mini program authorization token

The problem of too long parameters

Since the length of the scene parameter only supports 32 characters, if The parameters exceed 32 bits, how will we handle them?

Solution

The solution to the problem is: design a small program parameter table, store the generated parameters in the table, and generate the small program by setting the scene parameter as the primary key of this table. , after the mini program scans the code, it first requests the background to obtain the specific parameters of the mini program through the scene parameter.

Example below:

##

The above is the detailed content of How to generate sun code for WeChat applet in Java. For more information, please follow other related articles on the PHP Chinese website!