您可以使用内置的Java 2D API为此（基本 Sun 教程here).
基本上，您需要创建一个Servlet得到一个InputStream中的原始图像doGet()方法，通过 Java 2D API 传递它，然后将其写入OutputStreamHTTP 响应。然后你只需将这个 Servlet 映射到某个特定的url-pattern in web.xml, e.g. /thumbs/*并在中调用这个 ServletsrcHTML 的属性<img>元素。
这是一个基本的启动示例（您仍然需要按照自己想要的方式自行处理意外情况）：
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// First get image file name as request pathinfo (or parameter, whatever you want).
String imageFilename = request.getPathInfo().substring(1);
// And get the thumbnail dimensions as request parameters as well.
int thumbWidth = Integer.parseInt(request.getParameter("w"));
int thumbHeight = Integer.parseInt(request.getParameter("h"));
// Then get an InputStream of image from for example local disk file system.
InputStream imageInput = new FileInputStream(new File("/images", imageFilename));
// Now scale the image using Java 2D API to the desired thumb size.
Image image = ImageIO.read(imageInput);
BufferedImage thumb = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
Graphics2D graphics2D = thumb.createGraphics();
graphics2D.setBackground(Color.WHITE);
graphics2D.setPaint(Color.WHITE);
graphics2D.fillRect(0, 0, thumbWidth, thumbHeight);
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
// Write the image as JPG to the response along with correct content type.
response.setContentType("image/jpeg");
ImageIO.write(thumb, "JPG", response.getOutputStream());
}
Servlet 映射到web.xml如下：
<servlet>
<servlet-name>thumbServlet</servlet-name>
<servlet-class>com.example.ThumbServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>thumbServlet</servlet-name>
<url-pattern>/thumbs/*</url-pattern>
</servlet-mapping>
可以按如下方式使用：
<img src="thumbs/filename.jpg?w=100&h=100" width="100" height="100">
注意：不，这不能单独使用 JSP 来完成，因为它是一种不适合此任务的视图技术。
注 2：这是一项相当昂贵的（CPU 密集型）任务，请记住这一点。您可能需要考虑自己预先缓存或预生成拇指。
