如何在不重新加载应用程序的情况下在 Spring 控制器中上传后获取图像？

Question

在我的 Spring 控制器中，我编写了 return 资源文件夹中 JSP 页面上的图像的方法。但是，如果我更改资源（或）添加新资源，我的 InputStream 为空。当我重新加载应用程序时，它会再次运行。

What can I do to get images without reloading application?

我在控制器中的方法：

@ResponseBody
    @RequestMapping(value = "/image/{authorUsername}/{title}", method = RequestMethod.GET, produces = MediaType.IMAGE_JPEG_VALUE)
    public byte[] testphoto(HttpServletRequest request,
                            @PathVariable("authorUsername") String authorUsername,
                            @PathVariable("title") String title) throws IOException {
        InputStream in = servletContext.getResourceAsStream("/resources/uploadImages/zeus192/" + title + "/0.jpg");
        return IOUtils.toByteArray(in);
    }

在 JSP 页面上：

<img src="/image/${advert.authorUsername}/${advert.title}/">

已编辑：

    @ResponseBody
    @RequestMapping(value = "/image/{authorUsername}/{title}", method = RequestMethod.GET, produces = MediaType.IMAGE_JPEG_VALUE)
    public void testphoto(HttpServletRequest request, HttpServletResponse response,
                                         @PathVariable("authorUsername") String authorUsername,
                                         @PathVariable("title") String title) throws IOException {

        InputStream instream = servletContext.getResourceAsStream("/resources/uploadImages/zeus192/" + title + "/0.jpg");
        byte[] bytes =  IOUtils.toByteArray(instream);
        int contentLength = IOUtils.copy(new ByteArrayInputStream(bytes), response.getOutputStream());
        response.setContentLength(contentLength);
        response.setHeader("Content-Disposition", "inline;filename=\"" + "0.jpg" + "\"");
    }

已编辑 2：

@ResponseBody
@RequestMapping(value = "/image/{authorUsername}/{title}", method = RequestMethod.GET, produces = MediaType.IMAGE_JPEG_VALUE)
public void testphoto(HttpServletRequest request, HttpServletResponse response,
                                     @PathVariable("authorUsername") String authorUsername,
                                     @PathVariable("title") String title) throws IOException {

    String contextPath = request.getSession().getServletContext().getRealPath("");
    String directory = contextPath.substring(0,contextPath.length() - 18) + "/target/YaPokupay/src/main/webapp/resources/uploadImages/" + authorUsername + "/" + title + "/0.jpg";

    File file = new File(directory);
    String filePath = file.getPath(); // D:\Works\YaPokupay\target\YaPokupay\src\main\webapp\resources\uploadImages\zeus192\Картинка[=14=].jpg
    InputStream instream = this.getClass().getClassLoader().getResourceAsStream(filePath);

    byte[] bytes =  IOUtils.toByteArray(instream);
    int contentLength = IOUtils.copy(new ByteArrayInputStream(bytes), response.getOutputStream());
    response.setContentLength(contentLength);

    response.setHeader("Content-Disposition", "inline;filename=\"" + "0.jpg" + "\"");

}

Answer 1

这是从 Spring controller.Adding httpServletResponse 下载文件作为参数并将文件流设置为响应输出流的代码。

   @ResponseBody
    @RequestMapping(value = "/image/{authorUsername}/{title}", method = RequestMethod.GET, produces = MediaType.IMAGE_JPEG_VALUE)
    public void testphoto(HttpServletRequest request,HttpServletResponse response,
                            @PathVariable("authorUsername") String authorUsername,
                            @PathVariable("title") String title) throws IOException {
        InputStream in = servletContext.getResourceAsStream("/resources/uploadImages/zeus192/" + title + "/0.jpg");
        Byte[] bytes =  IOUtils.toByteArray(in);
        int contentLength = IOUtils.copy(new ByteArrayInputStream(bytes), response.getOutputStream());
        httpServletResponse.setContentLength(contentLength);
    }

如果您想在浏览器中呈现图像，请添加一个 header "Content-Disposition" 作为内联 else 附件，这会将文件下载到您的本地计算机。

if(inline){  // if you want to attachment to be inline
    response.setHeader("Content-Disposition", "inline;filename=\"" + fileName + "\"");
}else{
    response.setHeader("Content-Disposition", "attachment;filename=\"" + fileName + "\"");
}

Answer 2

这对我有用，因为同一 resource.My 资源的多个请求位于 (../ProjectName/src/main/webapp/resources/images/logos)

@Autowired
private ServletContext servletContext;

@RequestMapping(value = "/sampleJavaOperation", method = RequestMethod.GET)
    public void sampleJavaOperation(HttpServletRequest request, HttpServletResponse response) throws IOException {

        InputStream instream = servletContext.getResourceAsStream("/resources/images/logos/wavemaker_62x62.png");
        byte[] bytes =  IOUtils.toByteArray(instream);
        int contentLength = IOUtils.copy(new ByteArrayInputStream(bytes), response.getOutputStream());
        response.setContentLength(contentLength);
        response.setHeader("Content-Disposition", "inline;filename=\"" + "0.png" + "\"");
    }

如何在不重新加载应用程序的情况下在 Spring 控制器中上传后获取图像？

How to get images after upload in Spring controller without reload application?

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