1、使用servlet生成验证码
- Java code
package com.free.util;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.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class CodeMakerServlet extends HttpServlet{ /** * */ private static final long serialVersionUID = 1L; //生成随机类 Random random = new Random(); //验证码字体 private Font[] codeFont = { new Font("Times New Roman", Font.PLAIN,18), new Font("Times New Roman", Font.PLAIN, 18), new Font("Times New Roman", Font.PLAIN,18), new Font("Times New Roman", Font.PLAIN, 18) }; //验证码数字颜色 private Color[] color = { Color.BLACK, Color.RED, Color.DARK_GRAY, Color.BLUE }; String codeNumbers = ""; int width = 60, height = 20; // 处理 HTTP get 请求 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("生成验证码"); // 清空缓冲区 response.reset(); // 注意这里的MIME类型 response.setContentType("image/png"); // 设置页面不缓存 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); // 创建一个图像,验证码显示的图片大小 BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); // 设置背景 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); for (int i = 0; i < 4; i++) { drawCode(g, i); } //添加干扰线 drawNoise(g, 12); // 绘制边框 //g.setColor(Color.gray); //g.drawRect(0, 0, width - 1, height - 1); // 将验证码内容保存进session中，用于验证用户输入是否正确时使用 HttpSession session = request.getSession(true); session.removeAttribute("rand"); session.setAttribute("rand", codeNumbers); // 重设字符串 codeNumbers = ""; // 利用ImageIO类的write方法对图像进行编码 ServletOutputStream sos = response.getOutputStream(); ImageIO.write(image, "PNG", sos); sos.close(); } // 绘制验证码 public void drawCode(Graphics graphics, int i) { String number = String.valueOf(random.nextInt(10)); graphics.setFont(codeFont[i]); graphics.setColor(color[i]); //绘制验证码到图片X、Y graphics.drawString(number, 6 + i * 13,16); codeNumbers += number; } // 绘制干扰线 public void drawNoise(Graphics graphics, int lineNumber) { graphics.setColor(getRandColor(160,200)); for (int i = 0; i < lineNumber; i++) { int pointX1 = 1 + (int)(Math.random() * width); int pointY1 = 1 + (int)(Math.random() * height); int pointX2 = 1 + (int)(Math.random() * width); int pointY2 = 1 + (int)(Math.random() * height); graphics.drawLine(pointX1, pointY1, pointX2, pointY2); } } public Color getRandColor(int fc,int bc){//给定范围获得随机颜色 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); } // 处理 HTTP post 请求, 和doGet一样 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}