elementUI simple image upload component (width and height restrictions, upload limit, file size limit)

<template>
  <div class="component-upload-image">
    <el-upload
      multiple
      :action="uploadImgUrl"
      list-type="picture-card"
      :on-success="handleUploadSuccess"
      :before-upload="handleBeforeUpload"
      :limit="limit"
      :on-error="handleUploadError"
      :on-exceed="handleExceed"
      ref="imageUpload"
      :on-remove="handleDelete"
      :show-file-list="true"
      :headers="headers"
      :file-list="fileList"
      :on-preview="handlePictureCardPreview"
      :class="{ hide: this.fileList.length >= this.limit }"
    >
      <i class="el-icon-plus"></i>
    </el-upload>

    <!-- 上传提示 -->
    <div class="el-upload__tip" slot="tip" v-if="showTip">
      请上传
      <template v-if="fileSize">
        大小不超过 <b style="color: #f56c6c">{
   
   { fileSize }}MB</b>
      </template>
      <template v-if="fileType">
        格式为 <b style="color: #f56c6c">{
   
   { fileType.join("/") }}</b>
      </template>
      的文件
    </div>

    <el-dialog
      :visible.sync="dialogVisible"
      title="预览"
      width="800"
      append-to-body
    >
      <img
        :src="dialogImageUrl"
        style="display: block; max-width: 100%; margin: 0 auto"
      />
    </el-dialog>
  </div>
</template>

<script>
import { getToken } from '@/utils/auth'
import { listByIds, delOss } from '@/api/system/oss'

export default {
  props: {
    value: String,
    // 大小限制(MB)
    fileSize: {
      type: Number,
      default: 5
    },
    // 数量限制
    limit: {
      type: Number,
      default: 1
    },
    // 文件类型, 例如['png', 'jpg', 'jpeg']
    fileType: {
      type: Array,
      default: () => ['png', 'jpg', 'jpeg']
    },
    // 是否显示提示
    isShowTip: {
      type: Boolean,
      default: true
    }
  },
  data() {
    return {
      uploadFile: {},
      dialogImageUrl: '',
      dialogVisible: false,
      hideUpload: false,
      baseUrl: process.env.VUE_APP_BASE_API,
      uploadImgUrl: process.env.VUE_APP_BASE_API + '/system/oss/upload', // 上传的图片服务器地址
      headers: {
        Authorization: 'Bearer ' + getToken()
      },
      fileUrl: '',
      fileList: []
    }
  },
  watch: {
    value: {
      async handler(val) {
        if(val && val.length >0) {
          let item = {name: "", url: val, ossId: 0};
          this.fileList = this.fileList.concat(item);
          this.fileUrl = val;
        } else {
          this.fileList = [];
          this.fileUrl = "";
        }
      },
      deep: true,
      immediate: true
    }
  },
  computed: {
    // 是否显示提示
    showTip() {
      return this.isShowTip && (this.fileType || this.fileSize)
    }
  },
  methods: {
    beforeAvatarUpload(file) {
    const isJPG = file.type === 'image/jpg';
    const isPNG = file.type === 'image/png';
    const isLt20M = file.size / 1024 / 1024 < 20;
    if (!isJPG) {
        this.$message.error('上传图片的格式只能是 JPG或PNG 格式!');
    }
    if (!isPNG) {
        this.$message.error('上传图片的格式只能是 JPG或PNG 格式!');
    }
    if (!isLt20M) {
        this.$message.error('上传图片的大小不能超过 20M!');
    }
    const isSize = new Promise(function(resolve, reject) {
        let width = 320;
        let height = 320;
        let _URL = window.URL || window.webkitURL;
        let img = new Image();
        img.onload = function() {
            let valid = img.width == width && img.height == height;
            valid ? resolve() : reject();
        }
        img.src = _URL.createObjectURL(file);
    }).then(() => {
        return file;
    }, () => {
        this.$message.error('上传的图片宽高必须是320*320!');
        return Promise.reject();
    });
    return isPNG && isJPG && isSize && isLt20M;
},
    // 上传前loading加载
    handleBeforeUpload(file) {
      console.log('file',file)
      let isImg = false
      if (this.fileType.length) {
        let fileExtension = ''
        if (file.name.lastIndexOf('.') > -1) {
          fileExtension = file.name.slice(file.name.lastIndexOf('.') + 1)
        }
        isImg = this.fileType.some((type) => {
          if (file.type.indexOf(type) > -1) return true
          if (fileExtension && fileExtension.indexOf(type) > -1) return true
          return false
        })
      } else {
        isImg = file.type.indexOf('image') > -1
      }

      if (!isImg) {
        this.$modal.msgError(
          `文件格式不正确, 请上传${this.fileType.join('/')}图片格式文件!`
        )
        return false
      }
      if (this.fileSize) {
        const isLt = file.size / 1024 / 1024 < this.fileSize
        if (!isLt) {
          this.$modal.msgError(`上传头像图片大小不能超过 ${this.fileSize} MB!`)
          return false
        }
      }
      const isSize = new Promise(function(resolve, reject) {
        let width = 600;
        let height = 400;
        let _URL = window.URL || window.webkitURL;
        let img = new Image();
        img.onload = function() {
            let valid = img.width == width && img.height == height;
            valid ? resolve() : reject();
        }
        img.src = _URL.createObjectURL(file);
    }).then(() => {
        return file;
    }, () => {
        this.$message.error('上传的图片宽高必须是600*400!');
        return Promise.reject();
    });
    return isSize;

      this.$modal.loading('正在上传图片，请稍候...')
      this.number++
    },
    // 文件个数超出
    handleExceed() {
      this.$modal.msgError(`上传文件数量不能超过 ${this.limit} 个!`)
    },
    // 上传成功回调
    handleUploadSuccess(res, file) {
      if (res.code === 200) {
        this.uploadFile = {
          name: res.data.fileName,
          url: res.data.url,
          ossId: res.data.ossId
        }
        this.uploadedSuccessfully()
      } else {
        this.$modal.closeLoading()
        this.$modal.msgError(res.msg)
        this.$refs.imageUpload.handleRemove(file)
        this.uploadedSuccessfully()
      }
    },
    // 删除图片
    handleDelete(file) {
      console.log("handleDelete",file);
      this.$emit('input', "");
    },
    // 上传失败
    handleUploadError(res) {
      this.$modal.msgError('上传图片失败，请重试')
      this.$modal.closeLoading()
    },
    // 上传结束处理
    uploadedSuccessfully() {
      console.log("uploadedSuccessfully",this.uploadFile);
      this.$emit('input', this.uploadFile.url);
      this.$modal.closeLoading()
    },
    // 预览
    handlePictureCardPreview(file) {
      this.dialogImageUrl = file.url
      this.dialogVisible = true
    },
  }
}
</script>
<style scoped lang="scss">
// .el-upload--picture-card 控制加号部分
::v-deep.hide .el-upload--picture-card {
  display: none;
}
// 去掉动画效果
::v-deep .el-list-enter-active,
::v-deep .el-list-leave-active {
  transition: all 0s;
}

::v-deep .el-list-enter,
.el-list-leave-active {
  opacity: 0;
  transform: translateY(0);
}
</style>