如何使用SpringMVC上传、显示、下载和删除文件

您好，我正在尝试使用spring mvc进行上传文件、显示文件、下载文件和删除文件等操作。我成功上传文件和删除文件。所有操作都运行良好，但接下来发生的事情是，当我上传上传的文件或图像时，显示或下载两次并获得 java.lang.IllegalStateException:已为此响应调用getOutputStream

选择文件1： 选择文件2： 文件名 形象 下载 删去

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如果我正确理解了你的问题，你可以这样做：

public ResponseEntity<InputStreamResource> getFile(@PathVariable("idForm") String idForm)
{
    try
    {
        Student item = registerService.get(id);
        HttpHeaders respHeaders = new HttpHeaders();
        //Change it with your real content type
        MediaType mediaType = new MediaType("img","jpg");
        respHeaders.setContentType(mediaType);
        respHeaders.setContentLength(file.length());
        //I suppose you have a method "getFileName"
                //By using attachment you download the file; by using inline you should see the image in the browser
        respHeaders.setContentDispositionFormData("attachment", item.getFileName());
        InputStreamResource isr = new InputStreamResource(new ByteArrayOutputStream(item.getData()));
        return new ResponseEntity<InputStreamResource>(isr, respHeaders, HttpStatus.OK);
    }
    catch (Exception e)
    {
        String message = "Error; "+e.getMessage();
        logger.error(message, e);
        return new ResponseEntity<InputStreamResource>(HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

---

Angelo

请看，我在尝试了更多内容后更新了我的问题。如果使用响应输出流，则无法返回新的模型和视图；o您返回null o您使用我发布的代码

public ResponseEntity<InputStreamResource> getFile(@PathVariable("idForm") String idForm)
{
    try
    {
        Student item = registerService.get(id);
        HttpHeaders respHeaders = new HttpHeaders();
        //Change it with your real content type
        MediaType mediaType = new MediaType("img","jpg");
        respHeaders.setContentType(mediaType);
        respHeaders.setContentLength(file.length());
        //I suppose you have a method "getFileName"
                //By using attachment you download the file; by using inline you should see the image in the browser
        respHeaders.setContentDispositionFormData("attachment", item.getFileName());
        InputStreamResource isr = new InputStreamResource(new ByteArrayOutputStream(item.getData()));
        return new ResponseEntity<InputStreamResource>(isr, respHeaders, HttpStatus.OK);
    }
    catch (Exception e)
    {
        String message = "Error; "+e.getMessage();
        logger.error(message, e);
        return new ResponseEntity<InputStreamResource>(HttpStatus.INTERNAL_SERVER_ERROR);
    }
}