java验证码生成具体代码

 package com.gonvan.component.captcha; import java.awt.*; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.HashMap; import java.util.Map; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; /** * Created by yuerzm on 2016/3/14. */ public class CaptchaFactory { private static final char[]   CODE_SEQUENCE    = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" .toCharArray(); private static final int    DEFAULT_WIDTH    = 60; private static final int    DEFAULT_HEIGHT   = 20; private static final int    DEFAULT_CODE_LEN  = 4; private static final int    DEFAULT_CODE_X   = 13; private static final int    DEFAULT_CODE_Y   = 16; private static final int    DEFAULT_FONT_SIZE  = 18; private static final String   DEFAULT_FONT_FAMILY = "Times New Roman"; private static CaptchaFactory  instance      = new CaptchaFactory(); private int           width        = DEFAULT_WIDTH;            // 定义图片的width private int           height       = DEFAULT_HEIGHT;            // 定义图片的height private int           length       = DEFAULT_CODE_LEN;           // 定义图片上显示验证码的个数 private int           xx         = DEFAULT_CODE_X;            // 定义图片上显示验证码x坐标 private int           yy         = DEFAULT_CODE_Y;            // 定义图片上显示验证码y坐标 private int           fontSize      = DEFAULT_FONT_SIZE;          // 定义图片上显示验证码的字体大小 private String         fontFamily     = DEFAULT_FONT_FAMILY;         // 定义图片上显示验证码的个数 private CaptchaFactory() { } public static CaptchaFactory getInstance() { return instance; } /** * 配置宽高 * * @param w * @param h * @return */ public CaptchaFactory configWidthAndHeight(int w, int h) { instance.width = w; instance.height = h; return instance; } /** * 配置坐标 * * @param x * @param y * @return */ public CaptchaFactory configXY(int x, int y) { instance.xx = x; instance.yy = y; return instance; } /** * 配置字体大小 * * @param fontSize * @return */ public CaptchaFactory configFontSize(int fontSize) { instance.fontSize = fontSize; return instance; } /** * 配置字体 * * @param fontFamily * @return */ public CaptchaFactory configFontSize(String fontFamily) { instance.fontFamily = fontFamily; return instance; } public void write(HttpServletRequest request, HttpServletResponse response) throws IOException { // 将四位数字的验证码保存到Session中。 Map captcha = generate(); String randomCode = (String) captcha.get("captchaCode"); BufferedImage buffImg = (BufferedImage) captcha.get("captchaImg"); HttpSession session = request.getSession(); session.setAttribute("code", randomCode); // 禁止图像缓存。 response.setHeader("Pragma", "no-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); response.setContentType("image/jpeg"); // 将图像输出到Servlet输出流中。 ServletOutputStream outputStream = response.getOutputStream(); ImageIO.write(buffImg, "jpeg", outputStream); outputStream.close(); } public Map generate() throws IOException { // 定义图像buffer BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics gd = buffImg.getGraphics(); // 设定背景色 gd.setColor(getRandColor(200, 250)); gd.fillRect(0, 0, width, height); // 设定字体，字体的大小应该根据图片的高度来定。 gd.setFont(new Font(fontFamily, Font.PLAIN, fontSize)); // 创建一个随机数生成器类 Random random = new Random(); // 随机产生40条干扰线，使图象中的认证码不易被其它程序探测到。 gd.setColor(getRandColor(160, 200)); for (int i = 0; i <155; i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); gd.drawLine(x, y, x + xl, y + yl); } // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。 StringBuffer randomCode = new StringBuffer(); int red = 0, green = 0, blue = 0; // 随机产生 length 个验证码。 for (int i = 0; i  retval = new HashMap<>(); retval.put("captchaCode", randomCode.toString()); retval.put("captchaImg", buffImg); return retval; } /** * 给定范围获得随机颜色 * * @param fc *      最小值 * @param bc *      最大值 * @return Color */ private 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); } }