我也问一下:如何用jsp实现验证码功能???
<%@ page contentType="text/html;charset=gb2312" errorPage="/error.jsp" session="true" %>
<%@ page import="java.sql.*,java.text.*,java.util.*" %>
<%@ page import="com.sun.image.codec.jpeg.*,java.io.*,java.awt.*,java.awt.image.*" %>
<%
Font mFont=new Font("宋体", Font.PLAIN,12);
String s="";
int intCount=0;
intCount=(new Random()).nextInt(9999);//
if(intCount<1000)intCount+=1000;
s=intCount+"";
session=request.getSession (true);
session.setAttribute("validateCode",s);
response.setContentType("image/gif");
BufferedImage image=new BufferedImage(35,14,BufferedImage.TYPE_INT_RGB);
Graphics gra=image.getGraphics();
//设置背景色
gra.setColor(Color.yellow);
gra.fillRect(1,1,33,12);
//设置字体色
gra.setColor(Color.black);
gra.setFont(mFont);
//输出数字
char c;
for(int i=0;i<4;i++) {
c=s.charAt(i);
gra.drawString(c+"",i*7+4,11); //7为宽度,11为上下高度位置
}
JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);
encoder.encode(image);
out.close();
%>
运行出现错误:
--------------------------------------------------
D:\Program Files\Apache Software Foundation\Tomcat 5\work\Standalone\localhost\jspdemo\demo_jsp.java:77: cannot resolve symbol
[javac] symbol : method createJPEGEncoder (javax.servlet.jsp.JspWriter)
[javac] location: class com.sun.image.codec.jpeg.JPEGCodec
[javac] JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);
[javac] ^
[javac] 1 error
这是怎么回事?