Methods for WeChat development to activate the camera, display pictures locally, upload and download pictures

This article introduces the methods of setting up the camera, displaying pictures locally, uploading and downloading pictures in WeChat development

1. Configuration

After the page is introduced and authorized through jssdk, the wx object is passed in. First configure the required Interface

wx.config({    /* debug: true,  */
    appId: appid, 
    timestamp: timestamp, 
    nonceStr: nonceStr, 
    signature: signature,
    jsApiList: [
         'chooseImage',//拍照或从手机相册中选图接口
         'previewImage',//预览图片接口
         'uploadImage',//上传图片接口
         'downloadImage'//下载图片接口
 　　]
 });

2. Call up the photo/album

and use the following method Place it in the callback function that requires a click event

wx.chooseImage({
    count: 1, 
    sizeType: ['compressed'], 
    sourceType: ['album', 'camera'], 
    success: function (res) {
　　　　//var localIds = res.localIds;
    　 $('.driver-card img').prop('src',res.localIds[0]);
    　 uploadPhoto.uploadToWeixinServer(res.localIds[0],'car')
   }
});

##At this time we can see this effect, It means the transfer was successful! In the successful callback of the chooseImage method, I assign the selected photo to the src of the img that needs to be displayed (because I only have one photo here. If there are multiple photos, just use a loop assignment). In this way, I can directly display the photo I just took. /The selected photo in the album

3. Upload the photo

In the success callback of chooseImage above, you can see me The uploadToWeixinServer method is called, and the parameter is the Id of the local photo

uploadToWeixinServer: 1

After calling the uploadImage interface, the picture is uploaded to the WeChat server and the picture is returned. At this time, you need to use ajax to asynchronously upload it to your own server and call the "Get temporary material" interface provided by WeChat. Of course, it is not necessarily necessary to upload the photos immediately after selecting them. It must be based on actual business needs. There are also silent uploads (no progress prompts), or uploading together when the form is finally submitted.

js:

uploadToOwnerServer: function(serverId,type){
            $.ajax({
                data: {serverId:serverId,type:type},
                type : "POST",
                url : WX_ROOT + "wechat/uploadPhoto",
                success : function(json) {                    if (json) {                        var data = JSON.parse(json.data);                        if ('car' == type) 
                            uploadPhoto.options.carImage = data.path + data.name                        else
                            uploadPhoto.options.idCardImage = data.path + data.name
                        
                    }
                }
            });
        },

Controller

@RequestMapping(value = "/uploadPhoto", method = RequestMethod.POST)    public @ResponseBody HttpResult uploadPhoto(@RequestParam String serverId,@RequestParam String type) throws Exception{
        LOGGER.info("RestFul of uploadPhoto parameters serverId:{},type:{}",serverId,type);        
        try {            /** 将图片保存到本地服务器 **/
            String photoName = type + new Date().getTime() + UUID.randomUUID().toString();            
            //文件路径不存在则创建
            File saveFile = new File(PIC_PATH + type);            if (!saveFile.mkdir()) saveFile.mkdir();
            
            wechatService.saveImageToDisk(serverId, photoName, PIC_PATH + type + "/");
            LOGGER.info("Download the picture from weixin server pathL:{}",PIC_PATH + type + "/");
            JSONObject data = new JSONObject();
            data.put("name", type + "/" + photoName+".jpg");
            data.put("path", PIC_SERVER + "/");
            
            HttpResult rs = new HttpResult();
            rs.setCode(200);
            rs.setData(data.toJSONString());
            LOGGER.info("Download the picture from weixin server is successful!serverId:{},photoName:{}",serverId,photoName);
            LOGGER.info("HttpResult data:{}",rs.getData());            return rs;
        } catch (Exception e) {
            LOGGER.error("Download the picture from weixin server is error",serverId);            return null;
        }

Here I use a UUID to generate a primary key rule and define the image name through type + timestamp + unique string. If the upload is successful, the image address of its own server will be returned to the front end.

getInputStream

Call the temporary material interface provided by WeChat to download the image still on the WeChat server. The parameter is the media file ID submitted by the front end, and finally convert the file For the input stream object

/**
     * 根据文件id下载文件 
     * @param accessToken
     * @param mediaId 
     * @return 文件流对象     */
    public InputStream getInputStream(String accessToken, String mediaId) {  
        InputStream is = null;  
        String url = "http://www.php.cn/"+ accessToken + "&media_id=" + mediaId;  
        try {  
            URL urlGet = new URL(url);  
            HttpURLConnection http = (HttpURLConnection) urlGet.openConnection();  
            http.setRequestMethod("GET"); // 必须是get方式请求  
            http.setRequestProperty("Content-Type","application/x-www-form-urlencoded");  
            http.setDoOutput(true);  
            http.setDoInput(true);  
            System.setProperty("sun.net.client.defaultConnectTimeout", "30000");// 连接超时30秒  
            System.setProperty("sun.net.client.defaultReadTimeout", "30000"); // 读取超时30秒              http.connect();  
            // 获取文件转化为byte流  
            is = http.getInputStream();  
        } catch (Exception e) {  
            LOGGER.error("Failed to convert inputStream from weixin server,accessToken:{},mediaId:{}",accessToken,mediaId);
        }  
        return is;  
  
    }

service

parses the stream object through a loop and converts the file Write to your own server

public void saveImageToDisk(String mediaId, String picName, String picPath) throws Exception {  
        String accessToken = getBaseAccessToken();
        InputStream inputStream = getInputStream(accessToken, mediaId); 
        
        // 循环取出流中的数据
        byte[] data = new byte[1024];  
        int len = 0;  
        FileOutputStream fileOutputStream = null;  
        try {  
            fileOutputStream = new FileOutputStream(picPath+picName+".jpg");  
            while ((len = inputStream.read(data)) != -1) {  
                fileOutputStream.write(data, 0, len);  
            }  
            LOGGER.info("Write the fileInputStream is successful");
        } catch (IOException e) {  
            LOGGER.error("Write the fileInputStream is error");
        } finally {  
            if (inputStream != null) {  
                try {  
                    inputStream.close();  
                } catch (IOException e) {  
                    LOGGER.error("Close the fileInputStream is error");
                }  
            }  
            if (fileOutputStream != null) {  
                try {  
                    fileOutputStream.close();  
                } catch (IOException e) {  
                    LOGGER.error("Close the fileOutputStream is error");
                }  
            }  
        }  
    }

##

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