动态刷新实现图片验证码
java实现图片验证码ImageGenerator 生成一张包含四位随机数的图片 Java代码 package com.my.page; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.OutputStream; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 这个class主要实现随机生成一个4位数的验证码，并写入session， */ public class ImageGenerator extends HttpServlet { private static Color getRandColor(int fc, int bc) { Random random = new Random(); if (fc > 255) fc = 255; if (bc > 255) bc = 255; int r = fc + random.nextInt(bc - fc); int g = fc + random.nextInt(bc - fc); int b = fc + random.nextInt(bc - fc); return new Color(r, g, b); } private static String charsLong = "23456789abcdefghjklmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ"; private static String charsShort = "0123456789"; private static String chars = charsLong; @Override public void doGet(HttpServletRequest request, HttpServletResponse response) { try { int charsLength = chars.length(); response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); int width = 75, height = 20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); Random random = new Random(); g.setColor(getRandColor(200, 250)); g.fillRect(0, 0, width, height); g.setFont(new Font("Times New Roman", Font.ITALIC, height)); g.setColor(getRandColor(160, 200)); for (int i = 0; i < 35; i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x, y, x + xl, y + yl); } StringBuilder sRand = new StringBuilder(); String[] fontNames = { "Times New Roman", "Arial", "Book antiqua", "" }; for (int i = 0; i < 4; i++) { g.setFont(new Font(fontNames, Font.ITALIC, height)); char rand = chars.charAt(random.nextInt(charsLength)); sRand.append(rand); g.setColor(new Color(20 + random.nextInt(110), 20 + random .nextInt(110), 20 + random.nextInt(110))); g.drawString(String.valueOf(rand), 16 * i + random.nextInt(6) + 3, height - random.nextInt(4)); } g.setColor(getRandColor(160, 200)); for (int i = 0; i < 19; i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(width); int yl = random.nextInt(width); g.drawLine(x, y, x + xl, y + yl); } request.getSession().setAttribute("Login_Image_Code", sRand.toString()); g.dispose(); try { Thread.sleep(100); } catch (Exception ex) { } OutputStream os = response.getOutputStream(); ImageIO.write(image, "JPEG", os); os.flush(); os.close(); } catch (Exception ex) { } } }package com.my.page;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 这个class主要实现随机生成一个4位数的验证码，并写入session， */public class ImageGenerator extends HttpServlet { private static Color getRandColor(int fc, int bc) {Random random = new Random();if (fc > 255) fc = 255;if (bc > 255) bc = 255;int r = fc + random.nextInt(bc - fc);int g = fc + random.nextInt(bc - fc);int b = fc + random.nextInt(bc - fc);return new Color(r, g, b); } private static String charsLong = "23456789abcdefghjklmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ"; private static String charsShort = "0123456789"; private static String chars = charsLong; @Override public void doGet(HttpServletRequest request, HttpServletResponse response) {try { int charsLength = chars.length(); response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); int width = 75, height = 20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); Random random = new Random(); g.setColor(getRandColor(200, 250)); g.fillRect(0, 0, width, height); g.setFont(new Font("Times New Roman", Font.ITALIC, height)); g.setColor(getRandColor(160, 200)); for (int i = 0; i < 35; i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x, y, x + xl, y + yl); } StringBuilder sRand = new StringBuilder(); String[] fontNames = { "Times New Roman", "Arial", "Book antiqua", "" }; for (int i = 0; i < 4; i++) { g.setFont(new Font(fontNames, Font.ITALIC, height)); char rand = chars.charAt(random.nextInt(charsLength)); sRand.append(rand); g.setColor(new Color(20 + random.nextInt(110), 20 + random .nextInt(110), 20 + random.nextInt(110))); g.drawString(String.valueOf(rand), 16 * i + random.nextInt(6) + 3, height - random.nextInt(4)); } g.setColor(getRandColor(160, 200)); for (int i = 0; i < 19; i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(width); int yl = random.nextInt(width); g.drawLine(x, y, x + xl, y + yl); } request.getSession().setAttribute("Login_Image_Code", sRand.toString()); g.dispose(); try { Thread.sleep(100); } catch (Exception ex) { } OutputStream os = response.getOutputStream(); ImageIO.write(image, "JPEG", os); os.flush(); os.close();} catch (Exception ex) { } }}在web.xml加入一下内容 Java代码 <servlet> <servlet-name>imageGenerator</servlet-name> <servlet-class>com.my.page.ImageGenerator</servlet-class> </servlet> <servlet-mapping> <servlet-name>imageGenerator</servlet-name> <url-pattern>/image.jpg</url-pattern> </servlet-mapping> <servlet> <servlet-name>imageGenerator</servlet-name> <servlet-class>com.my.page.ImageGenerator</servlet-class></servlet> <servlet-mapping> <servlet-name>imageGenerator</servlet-name> <url-pattern>/image.jpg</url-pattern></servlet-mapping>运用 Java代码 <input type="text" class="txt" wicket:id="validate"/><br/> <img src="image.jpg" onclick= "this.src= 'image.jpg? '+(new Date()) "/>其中onclick事件作用是：单击该验证图片，进行刷新，实现看不清换一张的效果
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