用element的upload组件实现多图片上传和压缩的示例代码

//upload.vue
<el-upload
 :action= domain
 ref="upload"
 accept='image/jpeg,image/gif,image/png'
 :auto-upload="false"
 :http-request="upqiniu"
 :limit="limit"
 :multiple="multiple"
 list-type="picture-card"
 :before-upload="beforeUpload"
 :on-preview="handlePictureCardPreview"
 :on-change="handldChange"
 :on-remove="handleRemove">
 <i class="el-icon-plus"></i>
</el-upload>
<el-dialog :visible.sync="dialogVisible">
 <img width="100%" :src="/UploadFiles/2021-04-02/dialogImageUrl">

domain 指的是我们的上传地址，upqiniu 是我们自定义的上传方法，beforeUpload 是图片上传前执行的方法。关于该组件的其他用法可以在element的官方文档查阅：Upload 上传
2.对图片进行压缩


// upload.vue
imgQuality: 0.5, //压缩图片的质量

dataURItoBlob(dataURI, type) {
 var binary = atob(dataURI.split(',')[1]);
 var array = [];
 for(var i = 0; i < binary.length; i++) {
  array.push(binary.charCodeAt(i));
 }
 return new Blob([new Uint8Array(array)], {type: type});
},

beforeUpload(param) {
 //对图片进行压缩
 const imgSize = param.size / 1024 / 1024
 if(imgSize > 1) {
  const _this = this
  return new Promise(resolve => {
   const reader = new FileReader()
   const image = new Image()
   image.onload = (imageEvent) => {
    const canvas = document.createElement('canvas');
    const context = canvas.getContext('2d');
    const width = image.width * _this.imgQuality
    const height = image.height * _this.imgQuality
    canvas.width = width;
    canvas.height = height;
    context.clearRect(0, 0, width, height);
    context.drawImage(image, 0, 0, width, height);
    const dataUrl = canvas.toDataURL(param.type);
    const blobData = _this.dataURItoBlob(dataUrl, param.type);
    resolve(blobData)
   }
   reader.onload = (e => { image.src = e.target.result; });
   reader.readAsDataURL(param);
  })
 }
}


压缩图片实现起来比较简单。就是在beforeUpload()方法里面return一个Promise，Promise里面我们把图片的长度和宽度按比例进行缩小，并把图片画到canvas上，然后把canvas转成一个blod对象。
3.前端向后端请求上传token。


//upload.vue
upqiniu(param) {
 let filetype = ''
 if (param.file.type === 'image/png') {
  filetype = 'png'
 } else {
  filetype = 'jpg'
 }
 const formdata = {
  filetype: filetype,
  param: param
 }
 this.actionGetUploadToken(formdata)    
}

// vuex/action.js
actionGetUploadToken({commit}, obj) {
 const msg = {
  filetype: obj.filetype
 }
 usersApi.getImgUploadToken(msg).then((response) => {
  if(response.stateCode === 200) {
   commit('uploadImg', {'token': response.token, 'key': response.key, 'param': obj.param})
  } 
 }, (error) => {
  console.log(`获取图片上传凭证错误：${error}`)
  commit('uploadImgError')
 })
},


4.后端生成上传token，并发给前端，我用Python实现。


filetype = data.get('filetype')
# 构建鉴权对象
q = Auth(configs.get('qiniu').get('AK'), configs.get('qiniu').get('SK'))

# 生成图片名
salt = ''.join(random.sample(string.ascii_letters + string.digits, 8))
key = salt + '_' + str(int(time.time())) + '.' + filetype

# 生成上传 Token，可以指定过期时间等
token = q.upload_token(configs.get('qiniu').get('bucket_name'), key, 3600)
return Response({"stateCode": 200, "token": token, "key": key}, 200)


5.前端接收token，开始向服务器上传图片


// vuex/state.js
imgName: [], //图片名数组

// vuex/mutations.js
uploadImg(state, msg) {
 const config = {
  useCdnDomain: true,
  region: qiniu.region.z2
 }
 var putExtra = {
  fname: msg.param.file.name,
  params: {},
  mimeType: ["image/png", "image/jpeg", "image/gif"]
 };
 var observer = {
  next(res){

  },
  error(err){
   console.log(`图片上传错误信息：${err.message}`)
  }, 
  complete(res){
   console.log(`图片上传成功：${res.key}`)
   state.imgName.push(res.key)
  }
 }
 var observable = qiniu.upload(msg.param.file, msg.key, msg.token, putExtra, config)
 //上传开始
 var subscription = observable.subscribe(observer)
},


6.上传成功以后，将图片名存入数据库


// 用到upload.vue的界面
this.imgsList = this.imgName.map(key => `http://${this.qiniuaddr}/${key}`)
switch(this.imgsList.length) {
 case 4:
 this.img4 = this.imgsList[3]
 case 3:
 this.img3 = this.imgsList[2]
 case 2:
 this.img2 = this.imgsList[1]
 case 1:
 this.img1 = this.imgsList[0]
}
let obj = {
 goods_img1: this.img1,
 goods_img2:this.img2,
 goods_img3:this.img3,
 goods_img4:this.img4
}
//将信息发送给后端
this.actionPublish(obj)


以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。