import Vue from 'vue' 
import { Uploader } from 'vant' 
Vue.use(Uploader);

 <van-uploader>
  <van-button icon="plus" type="primary" :after-read="afterRead">    
   上传文件(识别条码)
 </van-button>
 </van-uploader>

afterRead(file) {
  var self = this;
  //调用上传回调函数 - upload
  this.upLoad(this.$baseUrl + "upload/uploadParsing", file,
  function (response) {
    if( response.msg.length >0){
     console.log(response.msg)
    }else{
      Toast.fail('识别失败，请重新上传条码！',3500)
    }
   });  

 },
 
 upLoad(url, file, func) {
    var fileBase64 =''
    // 创建Canvas对象(画布)
    debugger
    let canvas = document.createElement("canvas");
    // 获取对应的CanvasRenderingContext2D对象(画笔)
    let context = canvas.getContext("2d");
    // 创建新的图片对象
    let img = new Image();
    // 指定图片的DataURL(图片的base64编码数据)
    img.src = file.content;
    // 监听浏览器加载图片完成，然后进行进行绘制
    img.onload = () => {
      // 指定canvas画布大小，该大小为最后生成图片的大小
      canvas.width = 400;
      canvas.height = 300;
      /* drawImage画布绘制的方法。(0,0)表示以Canvas画布左上角为起点，400，300是将图片按给定的像素进行缩小。
      如果不指定缩小的像素图片将以图片原始大小进行绘制，图片像素如果大于画布将会从左上角开始按画布大小部分绘制图片，最后的图片就是张局部图。*/
 
      context.drawImage(img, 0, 0, 400, 300);
      // 将绘制完成的图片重新转化为base64编码，file.file.type为图片类型，0.92为默认压缩质量
      file.content = canvas.toDataURL(file.file.type, 0.92);
      fileBase64 = file.content
      // 最后将base64编码的图片保存到数组中，留待上传。43      console.log(fileBase64)
      //查询字典值
      this.$axios.post(url,{'fileBase64Code' :fileBase64})
      .then(function (response) {
       func(response.data);
      }.bind(this))
      .catch(function (error) {
        Toast.file("识别失败，请重新上传条码！",3500);
      })
   };
 },

<!-- 解析二维码 -->
　　<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>core</artifactId>
    <version>3.3.3</version>
  </dependency>
  <dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>javase</artifactId>
    <version>3.3.3</version>
  </dependency>


  <!-- Base64 -->
  <!-- https://mvnrepository.com/artifact/net.iharder/base64 -->
  <dependency>
    <groupId>net.iharder</groupId>
    <artifactId>base64</artifactId>
    <version>2.3.8</version>
  </dependency>

　　@ResponseBody
　　@RequestMapping(value = "/uploadParsing", method = RequestMethod.POST)
　　public ResponseMessage uploadParsing(@RequestBody imgUploadMessage uploadFile){
    ResponseMessage rm=new ResponseMessage();
    //解析Base64编码之后 读取条
    try {
      String imgStr = uploadFile.getFileBase64Code().substring(uploadFile.getFileBase64Code().indexOf(",")+1);
      Decoder decoder = Base64.getDecoder();
      byte[] base = decoder.decode(imgStr);
      for (int i = 0; i < base.length; ++i) {
        if (base[i] < 0) {
          base[i] += 256;
        }
      }
       ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(base);
       BufferedImage read = ImageIO.read( byteArrayInputStream);
        if (null==read) {
          rm.setMsg("解析失败");
          rm.setSuccess(false);
          return rm;
        }
        BufferedImageLuminanceSource source = new BufferedImageLuminanceSource(read);
        BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
        Map<DecodeHintType,Object> hints=new HashMap<>();
        hints.put(DecodeHintType.CHARACTER_SET,"GBK");
        hints.put(DecodeHintType.PURE_BARCODE,Boolean.TRUE);
        hints.put(DecodeHintType.TRY_HARDER,Boolean.TRUE);
  
        Result decode = new MultiFormatReader().decode(bitmap, hints);
        log.debug("条形码的内容是：" + decode.getText());
        rm.setMsg(decode.getText());
       
      } catch (Exception e) {
        e.printStackTrace();
        log.debug("解析失败：",e);
        rm.setSuccess(false);
        rm.setMsg("解析失败");
      }
     return rm;
  }