最近遇到一个项目，上传按钮并未在组件 a-upload-dragger 内，可以按照如下方式触发文件上传的事件：

 <a-upload-dragger
      ref="uploadDragger"
      accept="application/vnd.openxmlformats-officedocument.wordprocessingml.document, application/pdf, application/msword"
      :show-upload-list="false"
      :before-upload="file => { beforeUpload(file) }"
      :customRequest="file => { selfUpload(file) }"
      @change="info => { handleChange(info) }"
    >
     
      <div>
        <p class="ant-upload-text">
          拖拽文件到这里，或点击可上传文件
      </div>
    </a-upload-dragger>
 <a-button
        type="primary"
        @click="onClickUpload"
      >上传本地</a-button>

onClickUpload() {
        this.$refs.uploadDragger.$el.querySelector("input").click();
    }