--- title: Generating Dynamic Resources Based On URI Or Parameters order: 28 layout: page --- [[generating-dynamic-resources-based-on-uri-or-parameters]] = Generating dynamic resources based on URI or parameters You can dynamically generate responses based on e.g. query parameters by creating your own `RequestHandler` and registering it with the session. In this way, you can for instance create an image that draws a text, given as a parameter to the image. This has been done in the example below: [source,java] .... public class DynamicImageUI extends UI { public static final String IMAGE_URL = "myimage.png"; private final RequestHandler requestHandler = new RequestHandler() { @Override public boolean handleRequest(VaadinSession session, VaadinRequest request, VaadinResponse response) throws IOException { if (("/" + IMAGE_URL).equals(request.getPathInfo())) { // Create an image, draw the "text" parameter to it and output // it to the browser. String text = request.getParameter("text"); BufferedImage bi = new BufferedImage(100, 30, BufferedImage.TYPE_3BYTE_BGR); bi.getGraphics().drawChars(text.toCharArray(), 0, text.length(), 10, 20); response.setContentType("image/png"); ImageIO.write(bi, "png", response.getOutputStream()); return true; } // If the URL did not match our image URL, let the other request // handlers handle it return false; } }; @Override public void init(VaadinRequest request) { Resource resource = new ExternalResource(IMAGE_URL + "?text=Hello!"); getSession().addRequestHandler(requestHandler); // Add an image using the resource Image image = new Image("A dynamically generated image", resource); setContent(image); } @Override public void detach() { super.detach(); // Clean up getSession().removeRequestHandler(requestHandler); } } .... iffstats
path: root/src/main/javassist/bytecode/AccessFlag.java
blob: 736135ec425892b2ecccfe457466e9e302692293 (plain) 
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