| Voici un captcha (“Completely Automated Public Turing test to tell Computers and Humans Apart“) code visuel de vérification propre à éliminer tout saisie automatisée (robots, redirection) utilisable dans vos dev java (JSP, Servlet, Struts ou autres). Ce code a été trouvé sur dzone : http://snippets.dzone.com/tag/Captcha Perso je l‘utilise dans mes dev Struts : le JSP doit être appelé pour un affichage en tant qu‘image img src=“captcha.jsp” ; ce JSP présente un code aléatoire et stocke le dit code dans une variable de session ‘captcha‘ ; j‘utilise ensuite le validateur du formbean correspondant à mon formulaire pour vérifier l‘adéquation captcha saisi dans le formulaire / captcha choisi aléatoirement
<%@ page import="java.util.*"%>
<%@ page import="java.io.*"%>
<%@ page import="javax.servlet.*"%>
<%@ page import="javax.servlet.http.*"%>
<%@ page import="java.awt.*"%>
<%@ page import="java.awt.image.*"%>
<%@ page import="javax.imageio.*"%>
<%@ page import="java.awt.geom.*"%>
<%
//========================================================
// Kick Ass Captcha JSP
//
// Michael Connor 2007
//
// I just couldn't handle the thought of downloading a
// big jar and configuring some servlet.xml and having
// little to no control of anything...
// You can send in height and width parameters.
// The captcha value will be placed in the session in
// a parameter called 'captcha'
//
// Feel free to use this code and do whatever the hell
// you want to it.
//========================================================
response.setContentType("image/jpg"); try { Color backgroundColor = Color.red;
Color borderColor = Color.red;
Color textColor = Color.white;
Color circleColor = new Color(160, 160, 160);
Font textFont = new Font("Arial", Font.PLAIN, 24);
int charsToPrint = 6;
int width = request.getParameter("width") != null ? Integer.parseInt(request.getParameter("width")) : 150;
int height = request.getParameter("height") != null ? Integer.parseInt(request.getParameter("height")) : 80;
int circlesToDraw = 4;
float horizMargin = 20.0f;
float imageQuality = 0.95f; // max is 1.0 (this is for jpeg)
double rotationRange = 0.7; // this is radians
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g = (Graphics2D) bufferedImage.getGraphics(); //Draw an oval
g.setColor(Color.red);
g.fillRect(0, 0, width, height); // lets make some noisey circles
g.setColor(circleColor);
for (int i = 0; i < circlesToDraw; i++) {
int circleRadius = (int) (Math.random() * height / 2.0);
int circleX = (int) (Math.random() * width - circleRadius);
int circleY = (int) (Math.random() * height - circleRadius);
g.drawOval(circleX, circleY, circleRadius <strong> 2, circleRadius </strong> 2);
} g.setColor(textColor);
g.setFont(textFont); FontMetrics fontMetrics = g.getFontMetrics();
int maxAdvance = fontMetrics.getMaxAdvance();
int fontHeight = fontMetrics.getHeight(); // i removed 1 and l and i because there are confusing to users...
// Z, z, and N also get confusing when rotated
// 0, O, and o are also confusing...
// lowercase G looks a lot like a 9 so i killed it
// this should ideally be done for every language...
// i like controlling the characters though because it helps prevent confusion
String elegibleChars = "ABCDEFGHJKLMPQRSTUVWXYabcdefhjkmnpqrstuvwxy23456789";
char[] chars = elegibleChars.toCharArray(); float spaceForLetters = -horizMargin * 2 + width;
float spacePerChar = spaceForLetters / (charsToPrint - 1.0f); AffineTransform transform = g.getTransform(); StringBuffer finalString = new StringBuffer(); for (int i = 0; i < charsToPrint; i++) {
double randomValue = Math.random();
int randomIndex = (int) Math.round(randomValue * (chars.length - 1));
char characterToShow = chars[randomIndex];
finalString.append(characterToShow); // this is a separate canvas used for the character so that
// we can rotate it independently
int charImageWidth = maxAdvance * 2;
int charImageHeight = fontHeight * 2;
int charWidth = fontMetrics.charWidth(characterToShow);
int charDim = Math.max(maxAdvance, fontHeight);
int halfCharDim = (int) (charDim / 2); BufferedImage charImage = new BufferedImage(charDim, charDim, BufferedImage.TYPE_INT_ARGB);
Graphics2D charGraphics = charImage.createGraphics();
charGraphics.translate(halfCharDim, halfCharDim);
double angle = (Math.random() - 0.5) * rotationRange;
charGraphics.transform(AffineTransform.getRotateInstance(angle));
charGraphics.translate(-halfCharDim, -halfCharDim);
charGraphics.setColor(textColor);
charGraphics.setFont(textFont); int charX = (int) (0.5 <strong> charDim - 0.5 </strong> charWidth);
charGraphics.drawString("" + characterToShow, charX,
(int) ((charDim - fontMetrics.getAscent()) / 2 + fontMetrics.getAscent())); float x = horizMargin + spacePerChar * (i) - charDim / 2.0f;
int y = (int) ((height - charDim) / 2);
//System.out.println("x=" <ins> x </ins> " height=" <ins> height </ins> " charDim=" <ins> charDim </ins> " y=" <ins> y </ins> " advance=" <ins> maxAdvance </ins> " fontHeight=" <ins> fontHeight </ins> " ascent=" + fontMetrics.getAscent());
g.drawImage(charImage, (int) x, y, charDim, charDim, null, null); charGraphics.dispose();
} //Write the image as a jpg
Iterator iter = ImageIO.getImageWritersByFormatName("JPG");
if (iter.hasNext()) {
ImageWriter writer = (ImageWriter) iter.next();
ImageWriteParam iwp = writer.getDefaultWriteParam();
iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwp.setCompressionQuality(imageQuality);
writer.setOutput(ImageIO.createImageOutputStream(response.getOutputStream()));
IIOImage imageIO = new IIOImage(bufferedImage, null, null);
writer.write(null, imageIO, iwp);
} else {
throw new RuntimeException("no encoder found for jsp");
} // let's stick the final string in the session
request.getSession().setAttribute("captcha", finalString.toString()); g.dispose();
} catch (IOException ioe) {
throw new RuntimeException("Unable to build image", ioe);
} %>
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