JavaWeb项目生成验证码

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; import javax.servlet.http.HttpSession; import java.awt.*; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; /** * Created by HE on 2016/9/18. */ @WebServlet(name = "AuthCode") public class AuthCode extends HttpServlet { private static final int WIDTH = 60;//设置验证码图片宽度 private static final int HEIGHT = 20;//设置验证码图片高度 private static final int LENGTH = 4;//设置验证码长度 //设置验证码随机出现的字符 private static final String str = "1234567890" + "abcdefghijklmnopqrstuvwxyz" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; char[] chars = str.toCharArray();//将字符放在数组中方便随机读取 private static Random random = new Random(); protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置输出的类型为图片 response.setContentType("image/jpeg"); //设置不进行缓存 response.setHeader("pragma", "no-cache"); response.setHeader("cache-control", "no-cache"); response.setHeader("expires", "0"); BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_3BYTE_BGR); //画笔 Graphics graphics = image.getGraphics(); //设置背景颜色并绘制矩形背景 graphics.setColor(Color.WHITE); graphics.fillRect(0, 0, WIDTH, HEIGHT); //用于记录生成的验证码 String code = null; //生成验证码并绘制 for (int i = 0; i < LENGTH; i++) { String c = "" + chars[random.nextInt(str.length())]; graphics.setColor(getColor()); graphics.drawString(c, 10 * i + 10, 18); code += c; } //生成干扰点 for (int i = 0; i < 50; i++) { graphics.setColor(getColor()); graphics.drawOval(random.nextInt(60), random.nextInt(20), 1, 1); } //将生成的验证码存入session中，以便进行校验 HttpSession session = request.getSession(); session.setAttribute("code", code); //绘制图片 graphics.dispose(); //将图片输出到response中 ImageIO.write(image, "JPEG", response.getOutputStream()); } //随机生成颜色 private Color getColor() { return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)); } }