【JavaWeb】(11)Java实现验证码制作

package com.thr.servlet; import java.awt.Color; 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; public class ImageServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { BufferedImage bi = new BufferedImage(68, 22, BufferedImage.TYPE_INT_RGB); Graphics g = bi.getGraphics(); Color c = new Color(200, 150, 255); g.setColor(c); g.fillRect(0, 0, 68, 22); // 生成26个英文字母的数组 char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray(); // 随机获取4个字符 Random r = new Random(); int len = ch.length; int index = 0; StringBuffer sb = new StringBuffer(); for (int i = 0; i < 4; i++) { index = r.nextInt(len); g.setColor(new Color(r.nextInt(88), r.nextInt(188), r.nextInt(255))); g.drawString(ch[index] + "", i * 15 + 3, 18); sb.append(ch[index]); } req.getSession().setAttribute("check_code", sb.toString()); ImageIO.write(bi, "JPG", resp.getOutputStream()); } }