<el-button :loading="pdfIslock" v-if="isPDFFile(form.pic)" type="primary" style="margin: 15px 0" @click="previewPDF(form.pic)"> 
  预览pdf
</el-button>

//npm install pdfjs-dist //如果没有就得先安装

import pdf from 'vue-pdf';
components: {
    pdf,
  },

data(){
    return {
      pdfIslock: false,
      pdfUrl: "",
      showDialog: false,   
    }
}

previewPDF(url){
      if(this.pdfIslock){
        this.$message.warning("文件下载中")
        return
      }
      this.pdfIslock = true      
      if(!url){
        this.$message.error("请先上传文件")
        return
      }
      const that = this
      let params = {
        fileName: url.split("/").pop()
      }
//fileProxyPdf 是后端的接口 返回的是一个pdf
      fileProxyPdf(params).then((response) => {      
        const blob = new Blob([response.data], { type: 'application/pdf' });
        const ourl = window.URL.createObjectURL(blob);
        // 将Object URL赋值给pdfUrl
        this.pdfUrl = ourl
        this.showDialog = true    
        this.pdfIslock = false      
      }).catch(function(){
        that.$message.error("下载失败，请稍后重试")
        that.pdfIslock = false 
      });      
      //window.open(url, '_blank');
    },