PDF预览和下载(Springboot+Vue+Axios)

大致流程

后端传数据流，前端已Blob的形式接收，Blob转化成URL直接在浏览器打开。

Vue

两种形式：①直接在浏览器打开URL,打开后可以在PDF里面下载;②直接下载PDF

    private async handleInfo(row: any) {
      const { data,headers } = await read(row.name);
      console.log(headers)
      const url = window.URL.createObjectURL(
        new Blob([data], {
          type: "application/pdf;charset=UTF-8;"
        })
      );
      const link = document.createElement("a");
      link.href = url;
      // 下载的代码
      // link.setAttribute("download", 'test');
      // document.body.appendChild(link);
      // link.click();
      // document.body.removeChild(link);
      window.open(url); // 直接打开预览的代码
      setTimeout(() => {
        this.loading = false;
      }, 0.5 * 1000);
  }

API

文件以Blob的形式接收

export const readPDF =(name: string) =>
  request({
    url: `/api/file/readPDF/${name}`,
    responseType: 'blob'
  });

Service.java

void readPDF(Integer id, HttpServletResponse response) throws IOException();

ServiceImpl.java

 public void readPDF(Integer id, HttpServletResponse response) throws IOException { // 预览/下载PDF文件
        String filename = URLEncoder.encode("PDF" ,"UTF-8");
        response.setContentType("application/pdf");
        response.setHeader("filename",""+ filename + ".pdf");
        response.addHeader("Access-Control-Expose-Headers", "filename");

       // 获取数据库中的二进制数据
        QueryWrapper<File> queryWrapper = new QueryWrapper<File>() //利用mybatisPlus按id查询
                .eq("id",id);
        File file = fileMapper.selectOne(queryWrapper);
     
        ByteArrayInputStream in = new ByteArrayInputStream(file.getData());
        OutputStream out = response.getOutputStream();
        byte[] bytes = new byte[1024];
        while((in.read(bytes)) != -1) {
            out.write(bytes);
        }
        out.flush();
        in.close();
        out.close();
    }

Controller.java

application/octet-stream：以二进制流的方式传输文件，只能传输一个。

 @GetMapping(
            value = "/getPDF/{id}",
            produces = {"application/octet-stream;charset=UTF-8"}
    )
    public void readPDF(@PathVariable Integer id, HttpServletResponse response) throws IOException {
       fileService.read(id,response);
    }