使用jsp将动态生成的图像显示给浏览器 [英] Display dynamically generated image to the browser using jsp

问题描述

我正在使用jsp/servlets处理图像的小项目，因为我动态生成了一些图像(实际上我将两个图像共享解密为一个)，解密后的图像必须直接显示给浏览器而不保存为文件在文件系统中.

I am doing a small project with images using jsp/servlets.In that I generate some image dynamically(actually I'll decrypt two image shares as one).That decrypted image must be displayed directly to browser without saving it as file in filesystem.

Crypting c=new Crypting();
BufferedImage imgKey;
BufferedImage imgEnc;
imgKey = ImageIO.read(new File("E:/Netbeans Projects/banking/web/Key.png"));
imgEnc=ImageIO.read(new File("E:/Netbeans Projects/banking/build/web/upload/E.png"));
BufferedImage imgDec=Crypting.decryptImage(imgKey,imgEnc);

当我将其存储在文件系统中并使用<img>显示时，它不会显示图像.重新加载时，它会显示图像.因此，IDE的后端工作存在问题. 任何帮助请...

When I store it in filesystem and display it using <img> it does not show the image.When reloaded it shows the image.So it is problem with the backend work of IDE. Any help pls...

推荐答案

1. 制作一个servlet来生成图像.
2. 使用属性为src的html img标签作为生成资源的路径.

弹簧靴示例(QR码). Servlet

Example in spring boot (QR Codes). Servlet

public class QRCodeServlet extends HttpServlet {
@Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  String url = req.getParameter("url");
  String format =  req.getParameter("format");
  QRCodeFormat formatParam = StringUtils.isNotEmpty(format) && format.equalsIgnoreCase("PDF") ?
    QRCodeFormat.PDF : QRCodeFormat.JPG;

  if(formatParam.equals(QRCodeFormat.PDF))
    resp.setContentType("application/pdf");
  else
    resp.setContentType("image/jpeg");

  if(StringUtils.isNotBlank(url)) {
    ByteArrayOutputStream stream = QRCodeService.getQRCodeFromUrl(url, formatParam);
    stream.writeTo(resp.getOutputStream());
  }
 }
}

配置:

@Configuration
public class WebMvcConfig {
  @Bean
  public ServletRegistrationBean qrCodeServletRegistrationBean(){
    ServletRegistrationBean qrCodeBean =
    new ServletRegistrationBean(new QRCodeServlet(), "/qrcode");
    qrCodeBean.setLoadOnStartup(1);
    return qrCodeBean;
  }
}

控制器:

String qrcodeServletPrefix = "http://localhost:8082/qrcode?url="

String encodedUrl = URLEncoder.encode("http://exmaple.com?param1=value1&param2=value2",  "UTF-8");
modelAndView.addObject("qrcodepage", qrcodeServletPrefix + encodedUrl);
modelAndView.setViewName("contracts/activateProcessVasResult");

activateProcessVasResult.jsp

activateProcessVasResult.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<img src="<c:url value='${qrcodepage}'/>" />

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