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创建一个DrawImage Servlet，用来生成验证码图片:
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 | package gacl.response.study; 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.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 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(); } } |
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> < html > < head > < title >在Form表单中使用验证码</ title > < script type = "text/javascript" > //刷新验证码 function changeImg(){ document.getElementById("validateCodeImg").src="${pageContext.request.contextPath}/servlet/DrawImage?"+Math.random(); } </ script > </ head > < body > < form action = "${pageContext.request.contextPath}/servlet/CheckServlet" method = "post" > 验证码：< input type = "text" name = "validateCode" /> < img alt = "验证码看不清，换一张" src = "${pageContext.request.contextPath}/servlet/DrawImage" id = "validateCodeImg" onclick = "changeImg()" > < a href = "javascript:void(0)" onclick = "changeImg()" >看不清，换一张</ a > < br /> < input type = "submit" value = "提交" > </ form > </ body > </ html > |
DrawImage Servlet除了可以生成的字母和数字的组合的验证码图片之外，还可以生成汉字，纯数字，纯字母的验证码图片，只需要向DrawImage Servlet传递约定好的生成标识符参数即可，如下所示
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> < html > < head > < title >在Form表单中使用验证码</ title > < script type = "text/javascript" > //刷新验证码 function changeImg(obj,createTypeFlag){ document.getElementById(obj.id).src="${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag="+createTypeFlag+"&"+Math.random(); } </ script > </ head > < body > < form action = "${pageContext.request.contextPath}/servlet/CheckServlet" method = "post" > 数字字母混合验证码：< input type = "text" name = "validateCode" /> < img alt = "验证码看不清，换一张" src = "${pageContext.request.contextPath}/servlet/DrawImage" id = "validateCodeImg1" onclick = "changeImg(this,'nl')" > < br /> 中文验证码：< input type = "text" name = "validateCode" /> < img alt = "验证码看不清，换一张" src = "${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=ch" id = "validateCodeImg2" onclick = "changeImg(this,'ch')" > < br /> 英文验证码：< input type = "text" name = "validateCode" /> < img alt = "验证码看不清，换一张" src = "${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=l" id = "validateCodeImg3" onclick = "changeImg(this,'l')" > < br /> 数字验证码：< input type = "text" name = "validateCode" /> < img alt = "验证码看不清，换一张" src = "${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=n" id = "validateCodeImg4" onclick = "changeImg(this,'n')" > < br /> < input type = "submit" value = "提交" > </ form > </ body > </ html > |
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | package gacl.response.study; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * @author gacl * 服务器端接收到验证码后的处理 */ public class CheckServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String clientCheckcode = request.getParameter( "validateCode" ); //接收客户端浏览器提交上来的验证码 String serverCheckcode = (String) request.getSession().getAttribute( "checkcode" ); //从服务器端的session中取出验证码 if (clientCheckcode.equals(serverCheckcode)) { //将客户端验证码和服务器端验证比较，如果相等，则表示验证通过 System.out.println( "验证码验证通过！" ); } else { System.out.println( "验证码验证失败！" ); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } } |
http://www.cnblogs.com/xdp-gacl/p/3798190.html
本文转自yunlielai51CTO博客，原文链接：http://blog.51cto.com/4925054/1723064，如需转载请自行联系原作者