一 效果如下:
二 java 代码如下:

import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/DrawImg") public class DrawImg extends HttpServlet { private static final long serialVersionUID = 1L; public static final int WIDTH = 140; public static final int HEIGHT = 35; public static int RANDOMSTARTPOSITION=20; public DrawImg() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String createTypeFlag = request.getParameter("createTypeFlag"); BufferedImage bi = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB); Graphics g = bi.getGraphics(); // background g.setColor(Color.WHITE); g.fillRect(0, 0, WIDTH, HEIGHT); // border g.setColor(Color.BLUE); g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2); // randomLines g.setColor(Color.GREEN); for (int i = 0; i < 5; i++) { int x1 = new Random().nextInt(WIDTH); int y1 = new Random().nextInt(HEIGHT); int x2 = new Random().nextInt(WIDTH); int y2 = new Random().nextInt(HEIGHT); g.drawLine(x1, y1, x2, y2); } String random = drawRandomNum((Graphics2D) g, createTypeFlag); request.getSession().setAttribute("checkCode", random); response.setContentType("image/jpeg"); // noCache response.setDateHeader("expries", -1); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Pragma", "no-cache"); ImageIO.write(bi, "jpg", response.getOutputStream()); } private String drawRandomNum(Graphics2D g, String... createTypeFlag) { g.setColor(Color.RED); g.setFont(new Font("隶书", Font.BOLD, 16)); // 常用汉字编码 String baseChineseChar = "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"; String baseNumLetter = "0123456789ABCDEFGHJKLMNOPQRSTUVWXYZ"; String baseNum = "0123456789"; String baseLetter = "ABCDEFGHJKLMNOPQRSTUVWXYZ"; String baseChar = baseNumLetter; if (createTypeFlag.length > 0 && null != createTypeFlag[0]) { if (createTypeFlag[0].equals("ch")) { // 汉字 baseChar = baseChineseChar; } else if (createTypeFlag[0].equals("nl")) { // 字母和数字 baseChar = baseNumLetter; } else if (createTypeFlag[0].equals("n")) { // 数字 baseChar = baseNum; } else if (createTypeFlag[0].equals("l")) { // 字母 baseChar = baseLetter; } } return createRandomChar(g, baseChar); } private String createRandomChar(Graphics2D g, String baseChar) { StringBuffer sb = new StringBuffer(); String ch = ""; int x=RANDOMSTARTPOSITION; for (int i = 0; i < 4; i++) { ch = baseChar.charAt(new Random().nextInt(baseChar.length())) + ""; sb.append(ch); int degree = new Random().nextInt() % 30; g.rotate(degree * Math.PI / 180, x, 20); g.drawString(ch, x, 20); g.rotate(-degree * Math.PI / 180, x, 20); x += 30; } return sb.toString(); } }
三 html代码如下:

<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> <style> body{ margin:0; padding:0; font-size:12px; } #container { text-align:center; margin: 50px auto; } table td{ border:1px solid #000; padding:10px 20px; } </style> </head> <body> <table id="container" cellspacing="0" style="border-collapse:collapse;"> <thead> <tr> <td>验证码类型</td> <td>Display</td> <td>参数类型</td> </tr> </thead> <tbody> <tr> <td>默认:</td> <td><img src="DrawImg"/></td> <td></td> </tr> <tr> <td>汉字:</td> <td><img src="DrawImg?createTypeFlag=ch"/></td> <td>?createTypeFlag=ch</td> </tr> <tr> <td>字母数字:</td> <td><img src="DrawImg?createTypeFlag=nl"/></td> <td>?createTypeFlag=nl</td> </tr> <tr> <td>数字:</td> <td><img src="DrawImg?createTypeFlag=n"/></td> <td>?createTypeFlag=n</td> </tr> <tr> <td>字母:</td> <td><img src="DrawImg?createTypeFlag=l"/></td> <td>?createTypeFlag=l</td> </tr> </tbody> </table> </body> </html>
四 总结:
生成验证码图片主要用到了一个BufferedImage类 ,源码下载:百度网盘