emelent-ui upload组件增加头部信息

<el-upload
        :class="['cover_uploader', itemData.className ]"
        :action="action"
        :accept="accept"
        :headers="headers"
        :show-file-list="false"
        :on-success="handleSuccess"
        :before-upload="beforeUpload">
            <el-image v-if="itemData.value" :src="itemData.value" class="card_img flex-eju-center" fit="cover">
            </el-image>
            <div v-if="uploadLoading" class="el-upload__text">
              <i class="el-icon-loading"></i>
            </div>
            <div v-else-if="itemData.value" class="el-upload__text">
                <i class="el-icon-refresh"></i>
                <span>更新图片</span>
            </div>
            <div v-else class="upload_default">
                <i class="el-icon-plus avatar-uploader-icon"></i>
                <span>上传封面</span>
            </div>
        <div class="el-upload__tip" slot="tip" v-if="itemData.tip1"><i>*</i>{{itemData.tip1}}</div>
        <div class="el-upload__tip" slot="tip" v-if="itemData.tip2"><i>*</i>{{itemData.tip2}}</div>
    </el-upload>

 headers: {
          'x-token': window.location.origin,
        }

注意，头部信息的key值和后端约定好，一般用中划线