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1、编辑一个带form表单的文件，index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><br /> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><br /> <html><br /> <head><br /> <base href="<%=basePath%>"></p> <p> <title>验证码</title><br /> </head></p> <p> <body><br /> <form name="form1" method="post" ><br /> 验证码：<input type="text" name="number"><br /> <img src="random.jsp" mce_src="random.jsp" id="random"align="" valign="absmiddle" hspace="5"><br /> <a href="javascript:show(document.getElementById('random'))" mce_href="javascript:show(document.getElementById('random'))" >验证码看不清</a><br/><br /> <input type="submit" name="ok" value="确定"><br /> </form><br /> </body><br /> </html><br />
2、编辑一个可以随机产生图片的页面，random.jsp
<%@ page autoFlush="false" pageEncoding="utf-8" import="java.util.*,java.awt.*,java.awt.image.*,com.sun.image.codec.jpeg.*,java.util.*" %></p> <p><%<br /> //set Chinese Char<br /> //Cody by JarryLi@gmail.com;<br /> //homepage:jiarry.126.com<br /> request.setCharacterEncoding("GBK");<br /> response.setCharacterEncoding("GBK");<br /> response.setContentType("text/html; charset=GBK");<br /> %><br /> <%<br /> String chose="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";</p> <p>char display[]={'0',' ','0',' ','0',' ','0'},ran[]={'0','0','0','0'},temp;</p> <p>Random rand=new Random();</p> <p>for(int i=0;i<4;i++)<br /> {</p> <p> temp=chose.charAt(rand.nextInt(chose.length()));</p> <p> display[i*2]=temp;</p> <p> ran[i]=temp;<br /> }</p> <p>String random=String.valueOf(display);</p> <p>session.setAttribute("random",String.valueOf(ran));<br /> %><br /> <%</p> <p> out.clear();<br /> response.setContentType("image/jpeg");<br /> response.addHeader("pragma","NO-cache");<br /> response.addHeader("Cache-Control","no-cache");<br /> response.addDateHeader("Expries",0);<br /> int width=80, height=30;<br /> BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);<br /> Graphics g = image.getGraphics();<br /> //以下填充背景颜色<br /> g.setColor(Color.GREEN);<br /> g.fillRect(0, 0, width, height);<br /> //设置字体颜色<br /> g.setColor(Color.RED);<br /> Font font=new Font("Arial",Font.PLAIN,20);<br /> g.setFont(font);<br /> //g.drawString(random,5,14);<br /> g.drawString(random,5,20);<br /> g.dispose();<br /> ServletOutputStream outStream = response.getOutputStream();<br /> JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(outStream);<br /> encoder.encode(image);<br /> outStream.close();<br /> %><br />
3、编辑index.jsp,调用xmlHttprequest
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%></p> <p><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><br /> <html><br /> <head><br /> <base href="<%=basePath%>"></p> <p> <title>验证码</title><br /> <mce:script type="text/javascript" ><!--<br /> function chk(){<br /> var number=document.form1.number.value;<br /> if(number.length==0){<br /> alert("请输入验证码！");<br /> document.form1.number.focus();<br /> return false;<br /> }<br /> else<br /> return true;<br /> }<br /> function show(o){<br /> var xmlHttp;<br /> try<br /> {<br /> // Firefox, Opera 8.0+, Safari<br /> xmlHttp=new XMLHttpRequest();<br /> }<br /> catch (e)<br /> {</p> <p> // Internet Explorer<br /> try<br /> {<br /> xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");<br /> }<br /> catch (e)<br /> {</p> <p> try<br /> {<br /> xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");<br /> }<br /> catch (e)<br /> {<br /> alert("您的浏览器不支持AJAX！");<br /> return false;<br /> }<br /> }<br /> }<br /> //xmlHttp.open("GET","random.jsp",true);<br /> //xmlHttp.send(null);<br /> var timenow = new Date().getTime();<br /> o.src="random.jsp?d="+timenow;<br /> }</p> <p>// --></mce:script><br /> </head></p> <p> <body><br /> <%<br /> String random=(String)session.getAttribute("random");<br /> %><br /> <form name="form1" method="post" action="compare.jsp" onsubmit="return chk()"><br /> 验证码：<input type="text" name="number"><br /> <img src="random.jsp" mce_src="random.jsp" id="random"align="" valign="absmiddle" hspace="5"><br /> <a href="javascript:show(document.getElementById('random'))" mce_href="javascript:show(document.getElementById('random'))" >验证码看不清</a><br/><br /> <input type="submit" name="ok" value="确定"><br /> </form><br /> </body><br /> </html><br />
显示结果：
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