jsp引用servlet生成的验证码代码演示
此演示代码主要包括以下三部分:
1.checkCode.java:用于生成验证码
2.checkCodeServler
3.check.jsp 验证
下面是checkCode.java的内容:
//用于获取四位随机数
privatecharmapTable[]={"0","1","2","3","4","5","6","7","8","9"};
//生成验证码,并返回随机生成的数字
publicStringgetEnsure(intwidth,intheight,OutputStreamos){
if(width<=0)
width=60;
if(height<=0)
height=20;
BufferedImageimage=newBufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphicsg=image.getGraphics();
//设定背景色
g.setColor(newColor(0xDCCCCC));
g.fillRect(0,0,width,height);
//画边框
g.setColor(Color.black);
g.drawRect(0,0,width-1,height-1);
//取随机产生的认证码
StringstrEnsure="";
//4代表4位验证码
for(inti=0;i<4;++i){
strEnsure+=mapTable[(int)(mapTable.length*Math.random())];
}
//将认证码显示到图象中
g.setColor(Color.red);
g.setFont(newFont("AtlanticInline",Font.PLAIN,14));
//画的具体坐标
Stringstr=strEnsure.substring(0,1);
g.drawString(str,8,14);
str=strEnsure.substring(1,2);
g.drawString(str,20,15);
str=strEnsure.substring(2,3);
g.drawString(str,35,18);
str=strEnsure.substring(3,4);
g.drawString(str,45,15);
//释放图形上下文
g.dispose();
try{
//输出图象到页面
ImageIO.write(image,"JPEG",os);
}catch(IOExceptione){
return"";
}
returnstrEnsure; //返回生成的随机数
}
再是checkCodeServlet的内容
publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)
throwsServletException,IOException{
doPost(request,response);
}
publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)
throwsServletException,IOException{
//禁用缓存,每次访问此页面,都重新生成
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires",0);
//生成验证码的实例对象
CheckCodeie=newCheckCode();
//调用里面的方法,返回的是生成的验证码中的字符串
Stringstr=ie.getEnsure(0,0,response.getOutputStream());
//获得session,并把字符串保存在session中,为后面的对比做基础
HttpSessionsession=request.getSession();
session.setAttribute("strEnsure",str);
}
然后是web.xml对servlet的配置
最后是jsp页面的引用 在jsp页面中,只需要将img的src的属性指向生成验证码的servlet就可以了,指向servle在web.xmlt映射的url。
<servlet>
<servlet-name>CheckServlet</servlet-name>
<servlet-class>com.blog.servlet.CheckServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CheckServlet</servlet-name>
<url-pattern>/check</url-pattern>
</servlet-mapping>
<html>
<head>
<title>验证码</title>
<scripttype="text/javascript"language="javascript">
//重新获取验证字符
functionchangeImage()
{
//单击触发图片重载事件,完成图片验证码的更换
document.getElementById("imgRandom").src=document.getElementById("imgRandom").src+"?";
}
</script>
</head>
<body>
<imgalt="看不清楚?点击更换验证码"src="check" width="100" height="50"id="imgRandom"onclick="changeImage()"/>
<ahref="javascript:changeImage();">看不清?</a>
</body>
</html>
相关文章