最近做到登录需要图片验证，很多图片验证都是在后台直接验证不满足我的需求。我需要做到输入密码后就立刻检验出密码的正确还是不是正确，这样提高了用户体验。
这就用到了ajax的内容！记录一下还是挺开心的~
1.首先是一个登录界面 login.jsp
1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> 2 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 3 <html> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6 <title>登录页面</title> 7 <script language="JavaScript" src="js/jquery.js"></script> 8 9 <script> 10 var url = $("#validateCodeImg").attr("src"); 11 $(".loginValidate").keyup(function(){ 12 $.post(url,{ 13 ajaxs:"Code", 14 inputCode:$(this).val(), 15 time:(new Date()).getTime() 16 },function(data,status){ 17 if(data=="false"){ 18 document.getElementById("btn").disabled="disabled"; 19 $("#results").html("验证码错误!"); 20 }else{ 21 $("#results").html("验证码正确!"); 22 document.getElementById("btn").disabled=!document.getElementById("btn").disabled; 23 24 } 25 }); 26 }); 27 </script> 28 29 30 <script type="text/javascript"> 31 //刷新验证码 32 function changeImg(){ 33 document.getElementById("validateCodeImg").src=document.getElementById("validateCodeImg").src+"?time="+(new Date()); 34 } 35 </script> 36 37 </head> 38 39 <body> 40 <form name="login_form" method="post" onSubmit="check()"> 41 <table> 42 <div class="loginbox"> 43 <ul> 44 <li><input type="text" name="validateCode" class="loginValidate" /> 45 <img alt="看不清，换一张" class="pic" src="servlet/DrawImage.serv" id="validateCodeImg" onclick="changeImg()"> 46 <span id="results"></span></li> 47 </ul> 48 </div> 49 </table> 50 </form> 51 </body> 52 53 </html>
2.创建一个servlet页面 进行绘制图片验证码
package hlj.press.group.action; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Enumeration; import java.util.Iterator; import java.util.Map; 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; /** * 生成随机图片，用来作为验证码 */ public class DrawImage extends HttpServlet { private static final long serialVersionUID = 3038623696184546092L; public static final int WIDTH = 120;//生成的图片的宽度 public static final int HEIGHT = 30;//生成的图片的高度 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String ajax = request.getParameter("ajaxs"); Enumeration<String> map = request.getParameterNames(); boolean flag = false; while(map.hasMoreElements()){ if( map.nextElement().toString().equals("ajaxs")) flag = true; } if(flag){ String check = (String)request.getSession().getAttribute("checkcode"); String inputCode = request.getParameter("inputCode"); // System.out.println(inputCode); response.setContentType("text/plain");//等同于response.setHeader("Content-Type", "image/jpeg"); //9.设置响应头控制浏览器不要缓存 response.setDateHeader("expries", -1); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Pragma", "no-cache"); if(inputCode.toLowerCase().equals(check.toLowerCase())){ response.getWriter().write("true"); }else{ response.getWriter().write("false"); } response.getWriter().flush(); return; }else{ String createTypeFlag = request.getParameter("createTypeFlag");//接收客户端传递的createTypeFlag标识 //1.在内存中创建一张图片 BufferedImage bi = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB); //2.得到图片 Graphics g = bi.getGraphics(); //3.设置图片的背影色 setBackGround(g); //4.设置图片的边框 setBorder(g); //5.在图片上画干扰线 drawRandomLine(g); //6.写在图片上随机数 //String random = drawRandomNum((Graphics2D) g,"ch");//生成中文验证码图片 //String random = drawRandomNum((Graphics2D) g,"nl");//生成数字和字母组合的验证码图片 //String random = drawRandomNum((Graphics2D) g,"n");//生成纯数字的验证码图片 //String random = drawRandomNum((Graphics2D) g,"l");//生成纯字母的验证码图片 String random = drawRandomNum((Graphics2D) g,createTypeFlag);//根据客户端传递的createTypeFlag标识生成验证码图片 //7.将随机数存在session中 request.getSession().setAttribute("checkcode", random); //8.设置响应头通知浏览器以图片的形式打开 response.setContentType("image/jpeg");//等同于response.setHeader("Content-Type", "image/jpeg"); //9.设置响应头控制浏览器不要缓存 response.setDateHeader("expries", -1); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Pragma", "no-cache"); //10.将图片写给浏览器 ImageIO.write(bi, "jpg", response.getOutputStream()); } } /** * 设置图片的背景色 * @param g */ private void setBackGround(Graphics g) { // 设置颜色 g.setColor(Color.WHITE); // 填充区域 g.fillRect(0, 0, WIDTH, HEIGHT); } /** * 设置图片的边框 * @param g */ private void setBorder(Graphics g) { // 设置边框颜色 g.setColor(Color.BLUE); // 边框区域 g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2); } /** * 在图片上画随机线条 * @param g */ private void drawRandomLine(Graphics g) { // 设置颜色 g.setColor(Color.GREEN); // 设置线条个数并画线 for (int i = 0; i < 5; i++) { int x1 = new Random().nextInt(WIDTH); int y1 = new Random().nextInt(HEIGHT); int x2 = new Random().nextInt(WIDTH); int y2 = new Random().nextInt(HEIGHT); g.drawLine(x1, y1, x2, y2); } } /** * 画随机字符 * @param g * @param createTypeFlag * @return * String... createTypeFlag是可变参数， * Java1.5增加了新特性：可变参数：适用于参数个数不确定，类型确定的情况，java把可变参数当做数组处理。注意：可变参数必须位于最后一项 */ private String drawRandomNum(Graphics2D g,String... createTypeFlag) { // 设置颜色 g.setColor(Color.RED); // 设置字体 g.setFont(new Font("宋体", Font.BOLD, 20)); //常用的中国汉字 String baseChineseChar = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6"; //数字和字母的组合 String baseNumLetter = "0123456789ABCDEFGHJKLMNOPQRSTUVWXYZ"; //纯数字 String baseNum = "0123456789"; //纯字母 String baseLetter = "ABCDEFGHJKLMNOPQRSTUVWXYZ"; //createTypeFlag[0]==null表示没有传递参数 if (createTypeFlag.length > 0 && null != createTypeFlag[0]) { if (createTypeFlag[0].equals("ch")) { // 截取汉字 return createRandomChar(g, baseChineseChar); }else if (createTypeFlag[0].equals("nl")) { // 截取数字和字母的组合 return createRandomChar(g, baseNumLetter); }else if (createTypeFlag[0].equals("n")) { // 截取数字 return createRandomChar(g, baseNum); }else if (createTypeFlag[0].equals("l")) { // 截取字母 return createRandomChar(g, baseLetter); } }else { // 默认截取数字和字母的组合 return createRandomChar(g, baseNumLetter); } return ""; } /** * 创建随机字符 * @param g * @param baseChar * @return 随机字符 */ private String createRandomChar(Graphics2D g,String baseChar) { StringBuffer sb = new StringBuffer(); int x = 5; String ch =""; // 控制字数 for (int i = 0; i < 4; i++) { // 设置字体旋转角度 int degree = new Random().nextInt() % 30; ch = baseChar.charAt(new Random().nextInt(baseChar.length())) + ""; sb.append(ch); // 正向角度 g.rotate(degree * Math.PI / 180, x, 20); g.drawString(ch, x, 20); // 反向角度 g.rotate(-degree * Math.PI / 180, x, 20); x += 30; } return sb.toString(); } }
在开发的过程中，不用ajax方法的时候 ，页面刷新之后前台获取到的验证码总是只能获取到最后一刷新的验证码。至今没搞懂问题到底出在哪里。
