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java - 来自 DB 的图像不会显示在 JSP 中：找不到 HTTP 请求的映射

问题描述

我在我的控制器中得到了这个：

@RequestMapping(value = "details", method = RequestMethod.GET)
public ModelAndView details(@Valid @ModelAttribute("MessageForm") final MessageForm form, @RequestParam("publicationid") String publicationid) {
    final Publication pub = ps.findById(Integer.valueOf(publicationid));
    final User user = us.findById(pub.getUserid());
    final ModelAndView mav = new ModelAndView("details");
    long myid = pub.getPublicationid();

    UploadFile ufa = imageServiceImp.findFirstById(Long.parseLong(publicationid));
    System.out.println("mi publication id es " +ufa.getPublicationId());
    System.out.println("mi id de upload es " + ufa.getId());
    System.out.println("mis bytes son " + ufa.getData().toString());
   // these prints work fine

    try {
        Image img = ImageIO.read(new ByteArrayInputStream(ufa.getData()));
        mav.addObject("image1", img);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    //other stuff
    return mav;
}

所以我在我的 JSP 中做了以下内容来显示图像：

  <img class="mySlides" src="<c:out value="${image1}" />" >

结果当我进入这个页面尝试我的程序时，我收到以下消息（当然图像不显示）：

 Sep 26, 2018 11:27:23 PM org.springframework.web.servlet.PageNotFound noHandlerFound
 WARNING: No mapping found for HTTP request with URI [/null/meinHaus/BufferedImage@4c8d98b4:%20type%20=%205%20ColorModel:%20] in DispatcherServlet with name 'dispatcher'

会发生什么？

我正在使用spring-mvc。

getData() 还返回一个 byte[] 类型的数组。

标签： javaspringspring-mvcjspdispatcher

解决方案

这不是您应该加载图像的方式。

在控制器类中编写一个方法，如下所示。

@RequestMapping(value = "/users/getProfilePic/{uniqueId}",method = RequestMethod.GET)
    public ResponseEntity<byte[]> getProfilePic(@PathVariable long uniqueId) {

        try{ 
            //reading image from tomcat folder you can read from the place where you stored the images
            String rootPath = System.getProperty("catalina.home");
            String profilePicDirectory = rootPath + File.separator + "profilePictures" + File.separator  + uniqueId;
            String profilePicFile = profilePicDirectory +  File.separator + uniqueId +".jpg";

            RandomAccessFile f = new RandomAccessFile(profilePicFile, "r");
            byte[] b = new byte[(int)f.length()];
            f.readFully(b);
            f.close();
            final HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.IMAGE_JPEG);
            return new ResponseEntity<byte[]>(b, headers, HttpStatus.OK);
        }catch(Exception ex){
            //ex.printStackTrace();
            final HttpHeaders headers = new HttpHeaders();
            return new ResponseEntity<byte[]>(null, headers, HttpStatus.NOT_FOUND);
            //return null;
        }
    }

然后在 jsp 页面中调用这个 url 来加载图像。

<img class="mySlides" src="/users/getProfilePic/${imageUniqueIdURL}" />

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