Java tutorial
/** * Copyright © 2012-2013 <a href="https://github.com/Dopas/dopas">Dopas</a> All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); */ package com.aistor.common.servlet; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.OutputStream; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.lang.math.NumberUtils; import org.apache.commons.lang3.StringUtils; /** * ???? * @author Zaric * @version 2013-3-15 */ @SuppressWarnings("serial") public class ValidateCodeServlet extends HttpServlet { private int w = 70; private int h = 26; public ValidateCodeServlet() { super(); } public void destroy() { super.destroy(); } public static boolean validate(HttpServletRequest request, String validateCode) { String code = (String) request.getSession().getAttribute("validateCode"); return validateCode.toUpperCase().equals(code); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String validateCode = request.getParameter("validateCode"); // AJAX??true if (StringUtils.isNotBlank(validateCode)) { response.getOutputStream().print(validate(request, validateCode) ? "true" : "false"); } else { this.doPost(request, response); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { createImage(request, response); } private void createImage(HttpServletRequest request, HttpServletResponse response) throws IOException { response.setHeader("Pragma", "no-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); response.setContentType("image/jpeg"); /* * ?? */ String width = request.getParameter("width"); String height = request.getParameter("height"); if (StringUtils.isNumeric(width) && StringUtils.isNumeric(height)) { w = NumberUtils.toInt(width); h = NumberUtils.toInt(height); } BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); /* * ? */ createBackground(g); /* * ? */ String s = createCharacter(g); request.getSession().setAttribute("validateCode", s); g.dispose(); OutputStream out = response.getOutputStream(); ImageIO.write(image, "JPEG", out); out.close(); } private Color getRandColor(int fc, int bc) { int f = fc; int b = bc; Random random = new Random(); if (f > 255) { f = 255; } if (b > 255) { b = 255; } return new Color(f + random.nextInt(b - f), f + random.nextInt(b - f), f + random.nextInt(b - f)); } private void createBackground(Graphics g) { // g.setColor(getRandColor(220, 250)); g.fillRect(0, 0, w, h); // ? for (int i = 0; i < 10; i++) { g.setColor(getRandColor(40, 150)); Random random = new Random(); int x = random.nextInt(w); int y = random.nextInt(h); int x1 = random.nextInt(w); int y1 = random.nextInt(h); g.drawLine(x, y, x1, y1); } } private String createCharacter(Graphics g) { char[] codeSeq = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; String[] fontTypes = { "\u5b8b\u4f53", "\u65b0\u5b8b\u4f53", "\u9ed1\u4f53", "\u6977\u4f53", "\u96b6\u4e66" }; Random random = new Random(); StringBuilder s = new StringBuilder(); for (int i = 0; i < 4; i++) { String r = String.valueOf(codeSeq[random.nextInt(codeSeq.length)]);//random.nextInt(10)); g.setColor(new Color(50 + random.nextInt(100), 50 + random.nextInt(100), 50 + random.nextInt(100))); g.setFont(new Font(fontTypes[random.nextInt(fontTypes.length)], Font.BOLD, 26)); g.drawString(r, 15 * i + 5, 19 + random.nextInt(8)); // g.drawString(r, i*w/4, h-5); s.append(r); } return s.toString(); } }