使用servlet将动态映像传递给JSP [英] Pass dynamic image to JSP with servlet

问题描述

我有一个桌面应用程序，用于创建图形2D对象，将其粘贴在面板中并绘制它。我试图使用servlets和jsps将此应用程序转换为网页。我已经在网上阅读了2天，无法解决如何做到这一点，我发现每个例子似乎都遗漏了一个重要的部分。我不想将图像保存到文件，因为每个用户将获得一个新的/不同的图像。

I have a desktop app that creates a graphics 2D object, sticks it in a panel and draws it. I am trying to convert this app to a webpage using servlets and jsps. I have been reading online for 2 days and can't wrap my head around how to do this, each example I find seems to leave out an important piece. I don't want to save the image to file because each user will get a new/different image.

我可以在servlet中创建图像以及其他响应变量并同时将它们传递给jsp吗？然后使用类似$ {response.image}的东西来调用图像。这似乎更可取，但似乎不起作用。

Can I create the image in the servlet along with the other response variables and pass them to the jsp at the same time? Then call the image using something like ${response.image}.This seems be preferable but doesn't seem to work.

或者我是否只需要一个单独的servlet图像（这看起来更难）？另外我如何准备要在HTML中用作图像的Graphics2D对象？

Or do I need a separate servlet just for the image (this seems harder)? Also how do I prepare the Graphics2D object to be used as an image in HTML?

推荐答案

您需要了解它是webbrowser谁必须根据检索到的HTML代码中找到的< img> 元素的网址下载所请求的图片，并且不网络服务器必须以某种方式在生成的HTML代码中内联图像的原始内容。

You need to understand that it's the webbrowser who has got to download the invididual images based on the URLs of the <img> elements found in the retrieved HTML code and that it's not the webserver who has got to inline the image's raw content in the produced HTML code somehow.

你真的需要为此创建一个独立的图像servlet来监听那些特定的URL < img> 元素。您可以通过在生成HTML代码期间在请求查询字符串中提供唯一的图像idenfitier或请求路径信息来使servlet可重用。

You really need to create a standalone image servlet for this which listens on those specific URLs of the <img> elements. You can make the servlet reuseable by providing an unique image idenfitier in the request query string or request path info during generating the HTML code.

例如

<img src="imageServlet?param1=value1&param2=value2" />

带

@WebServlet("/imageServlet")
public class ImageServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Create image based on request.getParameter() information.
        // Set proper content type by response.setContentType().
        // Write image to response.getOutputStream().
    }

}

参见：

• 如何从JSP页面中的数据库中检索和显示图像？ - 遵循类似的方法



See also:

• How to retrieve and display images from a database in a JSP page? - follows a similiar approach

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