java_验证码模块(servlet).md

java_验证码模块(servlet)

import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; 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 javax.servlet.http.HttpSession; @SuppressWarnings("serial" ) public class CheckCodeImage extends HttpServlet { private Font mFont = new Font( "Arial Black", Font.PLAIN, 16);//字体 /** * 获得随机颜色 * @param fc 颜色值下限 * @param bc 颜色值上限 * @return */ 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); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //取消缓存 response.setHeader( "Pragma", "No-cache" ); response.setHeader( "Cache-Control", "no-cache" ); response.setDateHeader( "Expires", 0); response.setContentType( "image/jpeg");// 设置响应内容为图片 int width = 58, height = 28;// 图片高度、宽度 BufferedImage image = new BufferedImage(width, height, BufferedImage. TYPE_INT_RGB);// 构造图片生成器 Graphics g = image.getGraphics(); //构造画板 Random random = new Random();// 随机数生成器 g.setColor(getRandColor(200, 250)); //获得随机颜色 g.fillRect(1, 1, width - 1, height - 1); //填充矩形 g.setColor( new Color(102, 102, 102)); g.drawRect(0, 0, width + 1, height - 1); //绘制矩形的边框 g.setFont( mFont);// 设置字体 g.setColor(getRandColor(160, 200)); for (int i = 0; i < 155; i++) {//画 155条随机直线 int x = random.nextInt(width - 1); int y = random.nextInt(height - 1); int xl = random.nextInt(6) + 1; int yl = random.nextInt(12) + 1; g.drawLine(x, y, x + xl, y + yl); } for (int i = 0; i < 70; i++) {//画 70条随机直线 int x = random.nextInt(width - 1); int y = random.nextInt(height - 1); int xl = random.nextInt(12) + 1; int yl = random.nextInt(6) + 1; g.drawLine(x, y, x - xl, y - yl); } String sRand = ""; for (int i = 0; i < 4; i++) { //画 4个随机字符串 String tmp = getRandomChar(); sRand += tmp; g.setColor( new Color(20 + random.nextInt(110), 20 + random .nextInt(110), 20 + random.nextInt(110))); g.drawString(tmp, 12 * i + 1, 18); //画随机字符串 } HttpSession session = request.getSession( true); session.setAttribute( "checkCodeImage", sRand); // 绑定这个随机字符串到 session g.dispose(); //释放资源 ImageIO. write(image, "JPEG", response.getOutputStream()); } private String getRandomChar() { // 获得随机字符串 int rand = (int) Math.round(Math.random() * 2); long itmp = 0; char ctmp = '\u0000' ; switch (rand) { case 1: itmp = Math. round(Math.random () * 25 + 65); ctmp = ( char) itmp; return String.valueOf(ctmp); case 2: itmp = Math. round(Math.random () * 25 + 97); ctmp = ( char) itmp; return String.valueOf(ctmp); default: itmp = Math. round(Math.random () * 9); return String.valueOf(itmp); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); } }