如何将BufferedImage转换为图像以在JSP上显示 [英] How to convert BufferedImage to image to display on JSP
问题描述
我想将 BufferedImage 转换为将在JSP页面上显示的图像。我怎样才能实现这个目标？
I would like to convert BufferedImage to an image that will display on JSP page. How can I achieve this?
推荐答案
首先，JSP是一种视图技术，提供了一个模板来编写HTML / CSS / JS和能够与后端Java代码交互以控制页面流和访问后端数据。你的问题更多的是HTML。
First, JSP is a view technology providing a template to write HTML/CSS/JS in and the ability to interact with backend Java code to control page flow and access backend data. Your problem is more in HTML.
现在，要在HTML页面中显示图像，您需要HTML < img> 元素。要定义/分配图像，您只需要让 src 属性指向一个URL。例如，
Now, to display an image in a HTML page, you need the HTML <img> element. To define/allocate an image, you just have to let the src attribute point to an URL. E.g.
<img src="url/to/image.jpg">
（它可以相对于当前上下文，也可以是绝对URL，例如以<$开头） c $ c> http：// ）
(it can be either relative to the current context, or an absolute URL, e.g. starting with http://)
如果图像是动态的，就像你的情况一样，你需要一个 Servlet ，它侦听匹配图像URL的 url-pattern 。例如，
If the image is dynamic, as in your case, you need to have a Servlet which listens on the url-pattern matching the image URL. E.g.
<img src="imageservlet/image.jpg">
（这里的servlet显然要映射到 / imageservlet / * 和图像标识符，这里是文件名，在这里可以通过 request.getPathInfo（））
(here the servlet is obviously to be mapped on /imageservlet/* and the image identifier, here the filename, is here available by request.getPathInfo())
< img src> 将触发GET请求，因此您只需实现 doGet（） servlet的方法。要发送HTTP响应，您需要做的就是将一些内容写入响应的 OutputStream ，以及一组代表内容的响应头（ Content-Type ， Content-Length 和/或 Content-disposition ）。您可以使用 ImageIO＃write（） 写一个 BufferedImage 到 OutputStream 。
The <img src> will fire a GET request, so you just have to implement doGet() method of the servlet. To send a HTTP response all you need to do is to write some content to the OutputStream of the response, along with a set of response headers representing the content (Content-Type, Content-Length and/or Content-disposition). You can use ImageIO#write() to write a BufferedImage to an OutputStream.
您可以找到这种图像servlet的基本示例这里。您只需要用 Files＃copy（） /ImageIO.html#write-java.awt.image.RenderedImage-java.lang.String-java.io.OutputStream-rel =nofollow noreferrer> ImageIO＃write（） 。
You can find a basic example of such an image servlet here. You just have to replace Files#copy() with ImageIO#write().
response.setContentType("image/png");
ImageIO.write(bufferedImage, "png", response.getOutputStream());
参见：
- 如何从JSP页面中的数据库中检索和显示图像？
- 在Java Web应用程序中从应用程序服务器外部提供静态数据的最简单方法
- How to retrieve and display images from a database in a JSP page?
- Simplest way to serve static data from outside the application server in a Java web application
See also:
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