Java 验证码

于 2013-11-28 15:04:00 发布
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文章标签： java web.xml


下面的例子是用Servlet生成的一个验证码，例子是模拟登陆。

login.jsp

[html] view plain copy
  1. <%@pagelanguage="java"contentType="text/html;charset=utf-8"
  2. pageEncoding="utf-8"%>
  3. <!DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
  4. <html>
  5. <head>
  6. <metahttp-equiv="Content-Type"content="text/html;charset=utf-8">
  7. <title>验证码</title>
  8. </head>
  9. <body>
  10. <formaction="${pageContext.request.contextPath}/servlet/LoginServlet">
  11. <tableborder="0"cellspacing="0"cellpadding="0"width="50%">
  12. <tr>
  13. <tdwidth="20%"align="right">用户名：</td><tdcolspan="2"><inputtype="text"name="username"value=""size="34"/></td>
  14. </tr>
  15. <tr>
  16. <tdwidth="20%"align="right">密码：</td><tdcolspan="2"><inputtype="password"name="password"value=""size="35"/></td>
  17. </tr>
  18. <tr>
  19. <tdwidth="20%"align="right">验证码：</td><tdwidth="21%"><inputtype="text"name="code"value=""size="15"/></td><tdalign="left"><imgsrc="${pageContext.request.contextPath}/servlet/ImageCodeMakerServlet"width="100px"height="30"/></td>
  20. </tr>
  21. </table>
  22. </form>
  23. </body>
  24. </html>

在web.xml中

[html] view plain copy
  1. <servlet>
  2. <servlet-name>login</servlet-name>
  3. <servlet-class>com.web.LoginServlet</servlet-class>
  4. </servlet>
  5. <servlet>
  6. <servlet-name>imageCodeMakerServlet</servlet-name>
  7. <servlet-class>com.web.ImageCodeMakerServlet</servlet-class>
  8. </servlet>
  9. <servlet-mapping>
  10. <servlet-name>login</servlet-name>
  11. <url-pattern>/servlet/LoginServlet</url-pattern>
  12. </servlet-mapping>
  13. <servlet-mapping>
  14. <servlet-name>imageCodeMakerServlet</servlet-name>
  15. <url-pattern>/servlet/ImageCodeMakerServlet</url-pattern>
  16. </servlet-mapping>


在后台Servlet里

[java] view plain copy
  1. importjava.io.IOException;
  3. importjavax.servlet.ServletException;
  4. importjavax.servlet.http.HttpServlet;
  5. importjavax.servlet.http.HttpServletRequest;
  6. importjavax.servlet.http.HttpServletResponse;
  7. importjavax.servlet.http.HttpSession;
  9. publicclassLoginServletextendsHttpServlet{
  11. @Override
  12. protectedvoidservice(HttpServletRequestrequest,HttpServletResponseresponse)
  13. throwsServletException,IOException{
  14. Stringusername=request.getParameter("username");
  15. Stringpassword=request.getParameter("password");
  16. Stringcode=request.getParameter("code");//页面，用户输入的验证码
  18. HttpSessionsession=request.getSession();
  19. StringrandCode=(String)session.getAttribute("randCode");//得到系统生成的验证码
  21. if(randCode.equals(code)){//验证码输入正确
  22. System.out.println("验证码输入正确");
  23. }else{
  24. System.out.println("验证码不正确");
  25. }
  26. }
  27. }


ImageCodeMakerServlet如下

[java] view plain copy
  1. importjava.awt.Color;
  2. importjava.awt.Font;
  3. importjava.awt.Graphics;
  4. importjava.awt.image.BufferedImage;
  5. importjava.io.IOException;
  6. importjava.util.Random;
  8. importjavax.imageio.ImageIO;
  9. importjavax.servlet.ServletException;
  10. importjavax.servlet.http.HttpServlet;
  11. importjavax.servlet.http.HttpServletRequest;
  12. importjavax.servlet.http.HttpServletResponse;
  14. publicclassImageCodeMakerServletextendsHttpServlet{
  16. publicImageCodeMakerServlet(){
  17. super();
  18. }
  20. publicvoiddestroy(){
  21. super.destroy();
  22. }
  24. publicvoidservice(HttpServletRequestrequest,HttpServletResponseresponse)
  25. throwsServletException,IOException{
  27. //首先设置页面不缓存
  28. response.setHeader("Pragma","No-cache");
  29. response.setHeader("Cache-Control","no-cache");
  30. response.setDateHeader("Expires",0);
  32. //定义图片的宽度和高度
  33. intwidth=90,height=40;
  34. //创建一个图像对象
  35. BufferedImageimage=newBufferedImage(width,height,
  36. BufferedImage.TYPE_INT_RGB);
  37. //得到图像的环境对象
  38. Graphicsg=image.createGraphics();
  40. Randomrandom=newRandom();
  41. //用随机颜色填充图像背景
  42. g.setColor(getRandColor(180,250));
  43. g.fillRect(0,0,width,height);
  44. for(inti=0;i<5;i++){
  45. g.setColor(getRandColor(50,100));
  46. intx=random.nextInt(width);
  47. inty=random.nextInt(height);
  48. g.drawOval(x,y,4,4);
  49. }
  50. //设置字体，下面准备画随机数
  51. g.setFont(newFont("",Font.PLAIN,40));
  52. //随机数字符串
  53. StringsRand="";
  54. for(inti=0;i<4;i++){
  55. //生成四个数字字符
  56. Stringrand=String.valueOf(random.nextInt(10));
  57. sRand+=rand;
  58. //生成随机颜色
  59. g.setColor(newColor(20+random.nextInt(80),20+random
  60. .nextInt(100),20+random.nextInt(90)));
  61. //将随机数字画在图像上
  62. g.drawString(rand,(17+random.nextInt(3))*i+8,34);
  64. //生成干扰线
  65. for(intk=0;k<12;k++){
  66. intx=random.nextInt(width);
  67. inty=random.nextInt(height);
  68. intxl=random.nextInt(9);
  69. intyl=random.nextInt(9);
  70. g.drawLine(x,y,x+xl,y+yl);
  71. }
  72. }
  74. //将生成的随机数字字符串写入Session
  75. request.getSession(false).setAttribute("randcode",sRand);
  76. //使图像生效
  77. g.dispose();
  78. //输出图像到页面
  79. ImageIO.write(image,"JPEG",response.getOutputStream());
  80. }
  82. /**
  83. *Initializationoftheservlet.<br>
  84. *
  85. *@throwsServletException
  86. *ifanerroroccurs
  87. */
  88. publicvoidinit()throwsServletException{
  89. //Putyourcodehere
  90. }
  91. /**
  92. *产生一个随机的颜色
  93. *
  94. *@paramfc
  95. *颜色分量最小值
  96. *@parambc
  97. *颜色分量最大值
  98. *@return
  99. */
  100. publicColorgetRandColor(intfc,intbc){
  101. Randomrandom=newRandom();
  102. if(fc>255){
  103. fc=255;
  104. }
  105. if(bc>255){
  106. bc=255;
  107. }
  108. intr=fc+random.nextInt(bc-fc);
  109. intg=fc+random.nextInt(bc-fc);
  110. intb=fc+random.nextInt(bc-fc);
  111. returnnewColor(r,g,b);
  112. }
  114. }
iteye_4639
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