下面的解决方案对我很有效

    @RequestMapping(value="/download")
    public void getLogFile(HttpSession session,HttpServletResponse response) throws Exception {
        try {

            String fileName="archivo demo.pdf";
            String filePathToBeServed = "C:\\software\\Tomcat 7.0\\tmpFiles\\";
            File fileToDownload = new File(filePathToBeServed+fileName);

            InputStream inputStream = new FileInputStream(fileToDownload);
            response.setContentType("application/force-download");
            response.setHeader("Content-Disposition", "attachment; filename="+fileName); 
            IOUtils.copy(inputStream, response.getOutputStream());
            response.flushBuffer();
            inputStream.close();
        } catch (Exception exception){
            System.out.println(exception.getMessage());
        }

    }

在我的情况下，我需要生成一些文件，所以url也必须生成。

对我来说是这样的:

@RequestMapping(value = "/files/{filename:.+}", method = RequestMethod.GET, produces = "text/csv")
@ResponseBody
public FileSystemResource getFile(@PathVariable String filename) {
    String path = dataProvider.getFullPath(filename);
    return new FileSystemResource(new File(path));
}

非常重要的是，mime类型在produces中，文件名也是链接的一部分所以你必须使用@PathVariable。

HTML代码是这样的:

<a th:href="@{|/dbreport/files/${file_name}|}">Download</a>

其中${file_name}是由thymleaf在控制器中生成的，即:result_20200225.csv，因此链接的整个url是:example.com/aplication/dbreport/files/result_20200225.csv。

点击链接后，浏览器问我如何处理文件-保存或打开。

我能很快想到的是，生成pdf并将其存储在webapp/downloads/< RANDOM-FILENAME>.pdf代码中，并使用HttpServletRequest发送一个转发到这个文件

request.getRequestDispatcher("/downloads/<RANDOM-FILENAME>.pdf").forward(request, response);

或者你可以这样配置你的视图解析器，

  <bean id="pdfViewResolver"
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="viewClass"
              value="org.springframework.web.servlet.view.JstlView" />
    <property name="order" value=”2″/>
    <property name="prefix" value="/downloads/" />
    <property name="suffix" value=".pdf" />
  </bean>

然后返回

return "RANDOM-FILENAME";

@RequestMapping(value = "/files/{file_name}", method = RequestMethod.GET)
public void getFile(
    @PathVariable("file_name") String fileName, 
    HttpServletResponse response) {
    try {
      // get your file as InputStream
      InputStream is = ...;
      // copy it to response's OutputStream
      org.apache.commons.io.IOUtils.copy(is, response.getOutputStream());
      response.flushBuffer();
    } catch (IOException ex) {
      log.info("Error writing file to output stream. Filename was '{}'", fileName, ex);
      throw new RuntimeException("IOError writing file to output stream");
    }

}

一般来说，当你有response.getOutputStream()时，你可以在那里写任何东西。您可以将此输出流作为将生成的PDF放置到生成器的位置。另外，如果你知道你要发送什么文件类型，你可以设置

response.setContentType("application/pdf");

您应该能够直接在响应上写入文件。类似的

response.setContentType("application/pdf");      
response.setHeader("Content-Disposition", "attachment; filename=\"somefile.pdf\""); 

然后在response.getOutputStream()上将该文件写入二进制流。记得在最后执行response.flush()，这样就可以了。

如下图所示

@RequestMapping(value = "/download", method = RequestMethod.GET)
public void getFile(HttpServletResponse response) {
    try {
        DefaultResourceLoader loader = new DefaultResourceLoader();
        InputStream is = loader.getResource("classpath:META-INF/resources/Accepted.pdf").getInputStream();
        IOUtils.copy(is, response.getOutputStream());
        response.setHeader("Content-Disposition", "attachment; filename=Accepted.pdf");
        response.flushBuffer();
    } catch (IOException ex) {
        throw new RuntimeException("IOError writing file to output stream");
    }
}

您可以在这里显示PDF或下载示例