Spring MVC图像控制器，在JSP中显示图像字节 [英] Spring MVC Image Controller, to display Image Bytes in JSP

问题描述

我有一个Spring MVC应用程序，其中一个JSP必须显示来自数据库的图像。

图像作为Blob存储在数据库中。 p>

显示它们的最简单方法是什么？什么样的servlet /控制器，我需要在JSP上显示图像字节？

我的理解是，我需要一个单独的控制器，说ImgController / id = ，这将显示基于请求参数的图像字节，然后在我的JSP我可以有img src =ImgController / id ...。但是如何实现和连接这个控制器？

任何帮助或示例将非常感激。非常感谢。

解决方案

最简单的解决方案输入OutputStream或ResponseEntity。

我更喜欢：返回ResponseEntity：

  @RequestMapping（value =/ reportTemplate / {id} / content，method = RequestMethod.GET）
 public ResponseEntity< byte []& downloadReportTemplateContent（
 @PathVariable（id）final ReportTemplate reportTemplate）
 throws IOException {
 ReportDatei file = reportTemplate.getFile（）; 
 
 String fileName = reportTemplate.getName（）+ EXCEL_FILE_NAME_ENDING; 
 HttpHeaders responseHeaders = httpHeaderExcelFileAttachment（fileName，
 datei.getDaten（）。length）; 
 return new ResponseEntity< byte []>（file.getDataArray（），
 responseHeaders，HttpStatus.OK）; 
} 
 
 
 public static HttpHeaders httpHeaderExcelFileAttachment（final String fileName，
 final int fileSize）{
 String encodedFileName = fileName.replace（' ''）.replace（''，'_'）; 
 
 HttpHeaders responseHeaders = new HttpHeaders（）; 
 responseHeaders.setContentType（MediaType.parseMediaType（application / vnd.ms-excel ））; 
 responseHeaders.setContentLength（fileSize）; 
 responseHeaders.set（Content-Disposition，attachment）; 
 responseHeaders.add（Content-Disposition，filename = \+ encodedFileName +'\'）; 
 return responseHeaders; 
} 
  

b $ b

但还有更多：

直接使用HttpServletResponse

  @RequestMapping（value =/ document / {id} / fileContent，method = RequestMethod.GET）
 public void getDocumentFileContent（final HttpServletResponse response，
 @PathVariable文档文档）
 throws IOException {
 FileContentUtil.writeFileContentToHttpResponse（document.getFile（），
 response，this.fileService）; 
} 
 
 public static void writeFileContentToHttpResponse（final CommonFileInfo fileInfo，
 final HttpServletResponse response，
 final FileService fileService）throws IOException {
 String mimeType = fileInfo。 getMimeType（）！= null？ fileInfo.getMimeType（）：CommonFileInfo.DEFAULT_MIME_TYPE; 
 String fileName = fileInfo.getOriginalName（）。replace（'''，''）; 
 
 FileContent fileContent = fileService.loadFileContent（fileInfo.getFileContentBusinessId（））; 
 .setContentType（mimeType）; 
 response.setContentLength（fileInfo.getSize（））; 
 response.addHeader（Content-Disposition，attachment; filename = \+ fileName +' ）; 
 
 response.getOutputStream（）。write（fileContent.getContent（））; 
 response.getOutputStream（）。flush（）; 
} 
  




I have a Spring MVC application, and one of the JSPs must show images coming from a database.

The images are stored in the DB as Blobs.

What is the easiest way to display them? What kind of servlet/controller do I need to show on the JSP the image bytes? Should be an easy question, but I haven't been able to find a full solution anywhere.

My understanding is that I need a separate controller, say ImgController/id=, which will display the image bytes based on a request parameter, and then in my JSP I can have img src="ImgController/id...". But how do I implement and wire this controller?

Any help or example would be really appreciated. Thanks a lot.

解决方案

The simplest solution (in terms so writing as less as possible) is a Spring MVC Controller Method with return Type OutputStream or ResponseEntity.

I prefer: return a ResponseEntity:

@RequestMapping(value = "/reportTemplate/{id}/content", method = RequestMethod.GET)
public ResponseEntity<byte[]> downloadReportTemplateContent(
        @PathVariable("id") final ReportTemplate reportTemplate)
        throws IOException {
    ReportDatei file = reportTemplate.getFile();

    String fileName = reportTemplate.getName() + EXCEL_FILE_NAME_ENDING;
    HttpHeaders responseHeaders = httpHeaderExcelFileAttachment(fileName,
                                    datei.getDaten().length);
    return new ResponseEntity<byte[]>(file.getDataArray(),
                                      responseHeaders, HttpStatus.OK);
}


public static HttpHeaders httpHeaderExcelFileAttachment(final String fileName,
        final int fileSize) {
    String encodedFileName = fileName.replace('"', ' ').replace(' ', '_');

    HttpHeaders responseHeaders = new HttpHeaders();
    responseHeaders.setContentType(MediaType.parseMediaType("application/vnd.ms-excel"));
    responseHeaders.setContentLength(fileSize);
    responseHeaders.set("Content-Disposition", "attachment");
    responseHeaders.add("Content-Disposition", "filename=\"" + encodedFileName + '\"');
    return responseHeaders;
}

But there are many more:

Use HttpServletResponse directly

@RequestMapping(value = "/document/{id}/fileContent", method = RequestMethod.GET)
    public void getDocumentFileContent(final HttpServletResponse response,
            @PathVariable("id") final Document document)
            throws IOException {
        FileContentUtil.writeFileContentToHttpResponse(document.getFile(),
                        response, this.fileService);
    }

    public static void writeFileContentToHttpResponse(final CommonFileInfo fileInfo,
              final HttpServletResponse response,
              final FileService fileService) throws IOException {
        String mimeType = fileInfo.getMimeType() != null ? fileInfo.getMimeType() : CommonFileInfo.DEFAULT_MIME_TYPE;
        String fileName = fileInfo.getOriginalName().replace('"', ' ');

        FileContent fileContent = fileService.loadFileContent(fileInfo.getFileContentBusinessId());
        response.setContentType(mimeType);
        response.setContentLength(fileInfo.getSize());
        response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + '"');

        response.getOutputStream().write(fileContent.getContent());
        response.getOutputStream().flush();
    }

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