add files to project

web/evercookie/assets/EvercookiePngServlet.java

@@ -0,0 +1,95 @@
+package evercookie;
+
+import java.awt.Color;
+import java.awt.RenderingHints;
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+import java.io.OutputStream;
+
+import javax.imageio.ImageIO;
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.Cookie;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * This is a Java Servlet port of evercookie_png.php, the server-side component
+ * of Evercookie that stores values in force-cached PNG image data.
+ * 
+ * Install this servlet at /evercookie_png.php in your web.xml (or add a @WebServlet
+ * annotation) and you won't even need to modify evercookie.js! This assumes
+ * that Evercookie's assets are in your web root.
+ * 
+ * Of course, if you have set $_ec_baseurl to something, you should install this
+ * at [$_ec_baseurl]evercookie_png.php. Remember, $ec_baseurl needs a trailing
+ * slash in the evercookie.js.
+ * 
+ * @author Gabriel Bauman <gabe@codehaus.org>
+ * 
+ */
+public class EvercookiePngServlet extends HttpServlet {
+
+	private static final long serialVersionUID = 1L;
+
+	public EvercookiePngServlet() {
+		super();
+	}
+
+	@Override
+	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+
+		boolean cookieExists = false;
+		String cookieValue = null;
+		Cookie[] cookies = req.getCookies();
+
+		if (null != cookies) {
+			// Iterate over cookies until we find one named evercookie_png
+			for (Cookie cookie : cookies)
+			{
+				if (cookie.getName().equals("evercookie_png")) {
+					cookieExists = true;
+					cookieValue = cookie.getValue();
+					break;
+				}
+			}
+		}
+
+		// If the cookie doesn't exist, send 304 Not Modified and exit.
+		if (!cookieExists) {
+			resp.setStatus(304);
+			return;
+		}
+
+		// Generate a PNG image from the cookie value.
+		BufferedImage image = new BufferedImage(200, 1, BufferedImage.TYPE_INT_ARGB);
+		image.createGraphics().setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_OFF);
+		int x = 0;
+
+		for (int i = 0; i < cookieValue.length(); i += 3) {
+			// Treat every 3 chars of the cookie value as an {R,G,B} triplet.
+			Color c = new Color(cookieValue.charAt(i), cookieValue.charAt(i + 1), cookieValue.charAt(i + 2));
+			image.setRGB(x++, 0, c.getRGB());
+		}
+
+		// The cookie was present; set up the response headers.
+		resp.setContentType("image/png");
+		resp.addHeader("Last-Modified", "Wed, 30 Jun 2010 21:36:48 GMT");
+		resp.addHeader("Expires", "Tue, 31 Dec 2033 23:30:45 GMT");
+		resp.addHeader("Cache-Control", "private, max-age=630720000");
+
+		// Send the generate image data as the response body.
+		OutputStream body = resp.getOutputStream();
+
+		try {
+			ImageIO.write(image, "png", body);
+		} finally {
+			body.close();
+		}
+
+		// And we're done.
+		resp.setStatus(200);
+		resp.flushBuffer();
+	}
+}