Vue + Element 自定义上传封面组件功能

<template>
  <div class="upload">
    <el-upload
      :class="{'hidden':mFileList.length > 0}"
      list-type="picture-card"
      :on-remove="handleRemove"
      :action="action"
      :before-upload="beforeUploadHandle"
      :on-success="successHandle"
      :on-change="changeHandle"
      :limit="1"
      :accept="accept"
      :on-exceed="handleExceed"
      :file-list="fileList"
      :on-preview="handlePictureCardPreview"
    >
      <i class="el-icon-plus"></i>
    </el-upload>
    <el-dialog :visible.sync="dialogVisible">
      <img width="100%" :src="dialogImageUrl" alt="" />
    </el-dialog>
  </div>
</template>

<script>
export default {
  props: {
    action: {
      type: String,
      default: "",
    },
    accept: {
      type: String,
      default: "",
    },
    fileList:{
      type: Array,
      default: () => [],
    },
  },
  watch: {
    fileList(newValue, oldValue) {
      this.mFileList = newValue
    }
  },
  data() {
    return {
      dialogVisible: false, //图片放大
      fileImg: "", //上传图片
      dialogImageUrl: "", //图片地址
      mFileList:this.fileList,
    };
  },
  methods: {
    handleRemove(file, fileList) {
      this.$emit("upload-remove", file);
    },
    handlePictureCardPreview(file) {
      this.dialogImageUrl = file.url;
      this.dialogVisible = true;
    },
    // 上传之前
    beforeUploadHandle(file) {
      if (file.type !== "image/jpeg" && file.type !== "image/png") {
        this.$message({
          message: "只支持jpg、png格式的图片！",
          type: "warning",
        });
        return false;
      }
      const isLt2M = file.size / 1024 / 1024 < 2;
      if (!isLt2M) {
        this.$message({
          message: "上传文件大小不能超过 2MB!",
          type: "warning",
        });
        return false;
      }
    },
    // 上传成功
    successHandle(response, file, fileList) {
      this.mFileList = fileList;
      if (response && response.code === 200) {
        this.$message.success("图片上传成功！");
        this.$emit("upload-success", response, file);
      } else {
        this.$message.error(response.msg);
      }
    },
    changeHandle(file, fileList) {
      if(file.response && file.response.code == 500) {
         this.$emit("upload-error",file);
      }
    },
    handleExceed(files, fileList) {
        this.$message.warning("只能上传1张图片！");
      },
  },
};
</script>
<style lang="scss">
.upload .hidden .el-upload--picture-card {
  display: none;
}
</style>

<template>
    <div>
        <el-form ref="dataForm"    label-width="80px">
            <el-form-item label="封面" prop="cover" class="is-required">
                <upload list-type="picture-card" :action="url" :accept="'.jpg,.png,.JPG,.PNG'" :fileList="fileList"
                    :limit="1" @upload-success="uploadFile" @upload-remove="removeFile" @upload-error="uploadError">
                </upload>
            </el-form-item>
        </el-form>
    </div>
</template>

<script>
    import Upload from '../components/cover-upload/index.vue'
    export default {
        components: {
            Upload
        },
        data() {
            return {
                url: "",
                fileList: [],
            }
        },
        methods: {
            uploadUrl() {
                this.url = "http://xxx.xxx.xxx.xxx:xxx/yyxt/admin/course/courseInfo/upload?token=075de0303b15a38833a30a7a3b494794"//上传图片的后台接口
            },
            uploadError(file) {
                this.fileList = [];
            },
            uploadFile(response, file) {
                this.fileList = [{
                    url: response.data,
                }, ];
            },
            removeFile(file) {
                this.fileList = [];
            },
        },
        mounted() {
            this.uploadUrl();
        }
    }
</script>