Spring MVC：如何从控制器返回图像？

Question

我正在尝试返回这样的图像。

 @RequestMapping(value = "admin/image/{userId}")
public ResponseEntity<byte[]> getPhoto(@PathVariable int userId) throws IOException {
    UserDB userDB = UserDBService.getUserWithId(userId);
    if (userDB != null) {
        try {
            byte[] image;
            try {
                String path = ApplicationPropertiesConstants.SAFESITE_DOCUMENTS_DIRECTORY + userDB.getSite().getId() + "\\342.png";
                InputStream is = new FileInputStream(path);
                BufferedImage img = ImageIO.read(is);
                ByteArrayOutputStream bos = new ByteArrayOutputStream();
                ImageIO.write(img, "png", bos);
                final HttpHeaders headers = new HttpHeaders();
                headers.setContentType(MediaType.IMAGE_PNG);

                return new ResponseEntity<byte[]>(IOUtils.toByteArray(is), headers, HttpStatus.CREATED);
            } catch (FileNotFoundException e) {
                image = org.apache.commons.io.FileUtils.readFileToByteArray(new File("dfd"));
            }

            return null;
        } catch (IOException ignored) {
        }
    }
    return null;
}

虽然当我访问 url 时图像不显示。

知道为什么会这样吗？我需要使用 Apache Tiles 吗？目前我正在使用 jstlView。

<bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver">
    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
    <property name="prefix" value="/WEB-INF/jsp/" />
    <property name="suffix" value=".jsp" />
</bean>

Answer 1

}

response.setContentType("text/plain");
response.setHeader("Content-Disposition", "attachment;filename=EDC-"+ title + ".txt");
ServletOutputStream out = response.getOutputStream();
out.print(myString.trim());
out.flush();
out.close();

Answer 2

获取您的图像文件并将其写入响应。

@RequestMapping(value = "/getImage", method = RequestMethod.GET)
  public void showImage(HttpServletResponse response) throws Exception {

    ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();

    try {
      BufferedImage image = //CALL_OR_CREATE_YOUR_IMAGE_OBJECT;
      ImageIO.write(image, "jpeg", jpegOutputStream);
    } catch (IllegalArgumentException e) {
      response.sendError(HttpServletResponse.SC_NOT_FOUND);
    }

    byte[] imgByte = jpegOutputStream.toByteArray();

    response.setHeader("Cache-Control", "no-store");
    response.setHeader("Pragma", "no-cache");
    response.setDateHeader("Expires", 0);
    response.setContentType("image/jpeg");
    ServletOutputStream responseOutputStream = response.getOutputStream();
    responseOutputStream.write(imgByte);
    responseOutputStream.flush();
    responseOutputStream.close();
  }

Answer 3

这样不行，你需要类似的东西

@RequestMapping(...)
void getImage(...) {
  response.setContentType(mimeType);
  response.setHeader("Content-Disposition", String.format("inline; filename=\"" + file.getName() +"\""));
  response.setContentLength((int)file.length());
  InputStream inputStream = new BufferedInputStream(new FileInputStream(file));
  FileCopyUtils.copy(inputStream, response.getOutputStream());
}