java如何实现简单的验证码功能

package verificationCode; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.awt.image.RenderedImage; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStream; import java.util.HashMap; import java.util.Map; import java.util.Random; import javax.imageio.ImageIO; public class generateCode { private static int width = 150;// 定义图片的width private static int height = 48;// 定义图片的height private static int codeCount = 4;// 定义图片上显示验证码的个数 private static int xx = 25; private static int fontHeight = 42; private static int codeY = 42; private static char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; /** * 生成一个map集合 * code为生成的验证码 * codePic为生成的验证码BufferedImage对象 * @return */ public static Map<String,Object> generateCodeAndPic() { // 定义图像buffer BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // Graphics2D gd = buffImg.createGraphics(); // Graphics2D gd = (Graphics2D) buffImg.getGraphics(); Graphics gd = buffImg.getGraphics(); // 创建一个随机数生成器类 Random random = new Random(); // 将图像填充为白色 gd.setColor(Color.WHITE); gd.fillRect(0, 0, width, height); // 创建字体，字体的大小应该根据图片的高度来定。 Font font = new Font("Fixedsys", Font.BOLD, fontHeight); // 设置字体。 gd.setFont(font); // 画边框。 gd.setColor(Color.BLACK); gd.drawRect(0, 0, width - 1, height - 1); gd.setFont(font); // 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。 int red = 0, green = 0, blue = 0; // 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(); // 随机产生codeCount数字的验证码。 for (int i = 0; i < codeCount; i++) { // 得到随机产生的验证码数字。 String code = String.valueOf(codeSequence[random.nextInt(36)]); // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。 red = random.nextInt(255); green = random.nextInt(255); blue = random.nextInt(255); // 用随机产生的颜色将验证码绘制到图像中。 gd.setColor(new Color(red, green, blue)); gd.drawString(code, (i + 1) * xx, codeY); // 将产生的四个随机数组合在一起。 randomCode.append(code); } for (int i = 0; i < 60; i++) { red = random.nextInt(255); green = random.nextInt(255); blue = random.nextInt(255); // 用随机产生的颜色将验证码绘制到图像中。 gd.setColor(new Color(red, green, blue)); int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(50); int yl = random.nextInt(50); gd.drawLine(x, y, x + xl, y + yl); } Map<String,Object> map =new HashMap<String,Object>(); //存放验证码 map.put("code", randomCode); //存放生成的验证码BufferedImage对象 map.put("codePic", buffImg); return map; } public static void main(String[] args) throws Exception { //创建文件输出流对象 File file = new File("WebRoot/image/"+System.currentTimeMillis()+".jpg"); FileOutputStream out = null; try { if (!file.exists()) { // 先得到文件的上级目录，并创建上级目录，在创建文件 file.getParentFile().mkdir(); file.createNewFile(); } out = new FileOutputStream(file); Map<String,Object> map = generateCode.generateCodeAndPic(); ImageIO.write((RenderedImage) map.get("codePic"), "jpeg", out); System.out.println("验证码的值为："+map.get("code")); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }

package verificationCode; import java.io.IOException; 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; @WebServlet("/checkCode") public class checkCode extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String code = request.getParameter("code"); response.setCharacterEncoding("utf-8");//保证格式正确 response.setContentType("text/html"); // 验证验证码 String sessionCode = request.getSession().getAttribute("code").toString(); if (code != null && !"".equals(code) && sessionCode != null && !"".equals(sessionCode)) { if (code.equalsIgnoreCase(sessionCode)) { response.getWriter().println("验证通过！"); } else { response.getWriter().println("验证失败！"); } } else { response.getWriter().println("验证失败！"); } } }

package verificationCode; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.awt.image.RenderedImage; import java.io.IOException; import java.util.HashMap; import java.util.Map; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; 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 verificationCode.generateCode; /** * Servlet implementation class CodeServlet */ @WebServlet("/getCode") public class CodeServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 调用工具类生成的验证码和验证码图片 Map<String, Object> codeMap = generateCode.generateCodeAndPic(); // 将四位数字的验证码保存到Session中。 HttpSession session = req.getSession(); session.setAttribute("code", codeMap.get("code").toString()); // 禁止图像缓存。 resp.setHeader("Pragma", "no-cache"); resp.setHeader("Cache-Control", "no-cache"); resp.setDateHeader("Expires", 0); resp.setContentType("image/jpeg"); // 将图像输出到Servlet输出流中。 ServletOutputStream sos; try { sos = resp.getOutputStream(); ImageIO.write((RenderedImage) codeMap.get("codePic"), "jpeg", sos); sos.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>验证码页面</title> <script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.js"></script> </head> <body> <form action="${pageContext.request.contextPath}/checkCode" method="post"> 请输入验证码：<input type="text" name="code" /> <div id=random> <img id="imgObj" alt="验证码" src="${pageContext.request.contextPath}/getCode"> </div><button id="b01" type="button">改变内容</button><br/> <input type="submit" value="提交" /> </form> </body> <script type="text/javascript"> $(function() { //response.getWriter().println("验证失败！"); }); $("#b01").click( function changeImg() { $("#random").html("<img id='imgObj' alt='验证码' src='${pageContext.request.contextPath}/getCode'>") var imgSrc = $("#imgObj"); var src = imgSrc.attr("src"); imgSrc.attr("src", chgUrl(src)); }); // 时间戳 // 为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳 function chgUrl(url) { var timestamp = (new Date()).valueOf(); url = url.substring(0, 20); if ((url.indexOf("&") >= 0)) { url = url + "×tamp=" + timestamp; } else { url = url + "?timestamp=" + timestamp; } return url; } </script> </html>

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