javascript - 通过ajax下载文件

Question

我需要通过ajax从服务器下载文件。问题是该文件未存储在服务器上。我的基于 java 的后端自动从请求参数生成文件并在响应正文中返回它:

  @RequestMapping(value = "/download", method = RequestMethod.GET)
  public void download(@RequestParam String description, @RequestParam Long logId, HttpServletResponse response) {
    try {
      InputStream fileContent = // getting file as byte stream
      response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
      response.setHeader("Content-Disposition", "attachment; filename=file.zip");
      ServletOutputStream responseOutputStream = response.getOutputStream();
      org.apache.commons.io.IOUtils.copy(fileContent, responseOutputStream);
      response.flushBuffer();
    } catch (IOException e) {
      logger.error("Attempt to download file failed", e);
    }
  }

所以我需要处理它并允许用户下载文件。我的客户端包含这个:

$.ajax({
  type: "GET",
  url: "/download",
  data: {
    description: "test",
    logId: 123
  },
  success: function(data) {
    var blob = new Blob([data]);
    var link = document.createElement('a');
    link.href = window.URL.createObjectURL(blob);
    link.download = "file.zip";
    link.click();
  }
})

Controller 返回文件，但随后什么也没有发生。我究竟做错了什么？

Answer 1

不要进行 AJAX 调用，而是将窗口的 href 设置为指向下载文件的 URL。然后将响应的内容类型更改为 application/x-download 并将响应的 header 设置为 Content-disposition:

response.setContentType("application/x-download");
response.setHeader("Content-disposition", "attachment; filename=" + fileName);
response.flushBuffer();

function download(fileName) {
    window.location.href = "/download?description=test&logId=123";
}

此外，请查看 this SO post它解决了与您遇到的问题类似的问题。