java实现验证码功能
在实现这个功能之前先简单了解一下
BufferedImage类
Graphics类
ImageIO类
有助于理解
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效果图：
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验证码实现类：
package com.tools; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.util.Random; /** * 验证码生成器 * */ public class VCodeGenerator { /** * 验证码来源 */ final private char[] code = { '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' }; /** * 字体 */ final private String[] fontNames = new String[]{ "黑体", "宋体", "Courier", "Arial", "Verdana", "Times", "Tahoma", "Georgia"}; /** * 字体样式 */ final private int[] fontStyles = new int[]{ Font.BOLD, Font.ITALIC|Font.BOLD }; /** * 验证码长度 * 默认4个字符 */ private int vcodeLen = 4; /** * 验证码图片字体大小 * 默认17 */ private int fontsize = 21; /** * 验证码图片宽度 */ private int width = (fontsize+1)*vcodeLen+10; /** * 验证码图片高度 */ private int height = fontsize+12; /** * 干扰线条数 * 默认3条 */ private int disturbline = 3; public VCodeGenerator(){} /** * 指定验证码长度 * @param vcodeLen 验证码长度 */ public VCodeGenerator(int vcodeLen) { this.vcodeLen = vcodeLen; this.width = (fontsize+1)*vcodeLen+10; } /** * 生成验证码图片 * @param vcode 要画的验证码 * @param drawline 是否画干扰线 * @return */ public BufferedImage generatorVCodeImage(String vcode, boolean drawline){ //创建验证码图片 BufferedImage vcodeImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB); Graphics g = vcodeImage.getGraphics(); //填充背景色 g.setColor(new Color(246, 240, 250)); g.fillRect(0, 0, width, height); if(drawline){ drawDisturbLine(g); } //用于生成伪随机数 Random ran = new Random(); //在图片上画验证码 for(int i = 0;i < vcode.length();i++){ //设置字体 g.setFont(new Font(fontNames[ran.nextInt(fontNames.length)], fontStyles[ran.nextInt(fontStyles.length)], fontsize)); //随机生成颜色 g.setColor(getRandomColor()); //画验证码 g.drawString(vcode.charAt(i)+"", i*fontsize+10, fontsize+5); } //释放此图形的上下文以及它使用的所有系统资源 g.dispose(); return vcodeImage; } /** * 获得旋转字体的验证码图片 * @param vcode * @param drawline 是否画干扰线 * @return */ public BufferedImage generatorRotateVCodeImage(String vcode, boolean drawline){ //创建验证码图片 BufferedImage rotateVcodeImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g2d = rotateVcodeImage.createGraphics(); //填充背景色 g2d.setColor(new Color(246, 240, 250)); g2d.fillRect(0, 0, width, height); if(drawline){ drawDisturbLine(g2d); } //在图片上画验证码 for(int i = 0;i < vcode.length();i++){ BufferedImage rotateImage = getRotateImage(vcode.charAt(i)); g2d.drawImage(rotateImage, null, (int) (this.height * 0.7) * i, 0); } g2d.dispose(); return rotateVcodeImage; } /** * 生成验证码 * @return 验证码 */ public String generatorVCode(){ int len = code.length; Random ran = new Random(); StringBuffer sb = new StringBuffer(); for(int i = 0;i < vcodeLen;i++){ int index = ran.nextInt(len); sb.append(code[index]); } return sb.toString(); } /** * 为验证码图片画一些干扰线 * @param g */ private void drawDisturbLine(Graphics g){ Random ran = new Random(); for(int i = 0;i < disturbline;i++){ int x1 = ran.nextInt(width); int y1 = ran.nextInt(height); int x2 = ran.nextInt(width); int y2 = ran.nextInt(height); g.setColor(getRandomColor()); //画干扰线 g.drawLine(x1, y1, x2, y2); } } /** * 获取一张旋转的图片 * @param c 要画的字符 * @return */ private BufferedImage getRotateImage(char c){ BufferedImage rotateImage = new BufferedImage(height, height, BufferedImage.TYPE_INT_ARGB); Graphics2D g2d = rotateImage.createGraphics(); //设置透明度为0 g2d.setColor(new Color(255, 255, 255, 0)); g2d.fillRect(0, 0, height, height); Random ran = new Random(); g2d.setFont(new Font(fontNames[ran.nextInt(fontNames.length)], fontStyles[ran.nextInt(fontStyles.length)], fontsize)); g2d.setColor(getRandomColor()); double theta = getTheta(); //旋转图片 g2d.rotate(theta, height/2, height/2); g2d.drawString(Character.toString(c), (height-fontsize)/2, fontsize+5); g2d.dispose(); return rotateImage; } /** * @return 返回一个随机颜色 */ private Color getRandomColor(){ Random ran = new Random(); return new Color(ran.nextInt(220), ran.nextInt(220), ran.nextInt(220)); } /** * @return 角度 */ private double getTheta(){ return ((int) (Math.random()*1000) % 2 == 0 ? -1 : 1)*Math.random(); } /** * @return 验证码字符个数 */ public int getVcodeLen() { return vcodeLen; } /** * 设置验证码字符个数 * @param vcodeLen */ public void setVcodeLen(int vcodeLen) { this.width = (fontsize+3)*vcodeLen+10; this.vcodeLen = vcodeLen; } /** * @return 字体大小 */ public int getFontsize() { return fontsize; } /** * 设置字体大小 * @param fontsize */ public void setFontsize(int fontsize) { this.width = (fontsize+3)*vcodeLen+10; this.height = fontsize+15; this.fontsize = fontsize; } /** * @return 图片宽度 */ public int getWidth() { return width; } /** * 设置图片宽度 * @param width */ public void setWidth(int width) { this.width = width; } /** * @return 图片高度 */ public int getHeight() { return height; } /** * 设置图片高度 * @param height */ public void setHeight(int height) { this.height = height; } /** * @return 干扰线条数 */ public int getDisturbline() { return disturbline; } /** * 设置干扰线条数 * @param disturbline */ public void setDisturbline(int disturbline) { this.disturbline = disturbline; } }
使用：
package com.servlet; import java.awt.image.BufferedImage; import java.io.IOException; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.tools.VCodeGenerator; import com.tools.VcodeHelper; public class LoginServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { getVCode(req, resp); } private void getVCode(HttpServletRequest request, HttpServletResponse response) throws IOException { //创建验证码生成器对象 VCodeGenerator vcGenerator = new VCodeGenerator(); //生成验证码 String vcode = vcGenerator.generatorVCode(); //将验证码保存在session域中,以便判断验证码是否正确 request.getSession().setAttribute("vcode", vcode); //生成验证码图片，两个方法选喜欢的用 BufferedImage vImg = vcGenerator.generatorRotateVCodeImage(vcode, true); //BufferedImage vImg = vcGenerator.generatorVCodeImage(vcode, true); //输出图像 ImageIO.write(vImg, "gif", response.getOutputStream()); } }
jsp页面：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>验证码</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="Content-Type" content="text/html;charset=utf-8"> <script type="text/javascript" src="js/jquery.min.js"></script> <script type="text/javascript"> $(function(){ $("#vcodeImg").click(function(){ this.src="LoginServlet?method=GetVCode&t="+new Date().getTime(); }); }); </script> </head> <body> <img title="点击图片切换验证码" id="vcodeImg" src="LoginServlet?method=GetVCode" > </body> </html>
