关于生成验证码！！

在jsp中怎么生成验证码啊？？需要添加额外的包吗？？？？
看了个方式！！是添加个jGraphic 那怎么做成验证码是”花“的？？就是那种防止用读取像素的方法电脑自动获得验证码！！

解决方案 »

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不要，给你一段代码吧，也不知道你要的是不是这种效果
servlet：package com.jhc;import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;public class YzmServlet extends HttpServlet { /**
* Constructor of the object.
*/
public YzmServlet() {
super();
} public char[] getRand() {
char ch[] = new char[4];
String s = "ABCDEFGHJKLMNPQRSTUVWXY3456789";
for (int i = 0; i < 4; i++) {
Random r = new Random();
ch[i] = s.charAt(r.nextInt(s.length()));
}
return ch;
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { BufferedImage image = new BufferedImage(80, 30, 4);
Graphics g = image.getGraphics();
g.setColor(Color.LIGHT_GRAY);
g.fillRect(0, 0, 80, 30);
g.setColor(Color.blue); char ch[] = this.getRand();
g.setFont(new Font("宋体", Font.BOLD, 20));
g.drawString("" + ch[0], 8, 15);
g.setColor(Color.magenta);
g.drawString("" + ch[1], 24, 22);
g.setColor(Color.magenta);
g.drawString("" + ch[2], 42, 18);
g.setColor(Color.black);
g.drawString("" + ch[3], 56, 25);
g.setColor(Color.black);
Random r = new Random();
g.drawLine(r.nextInt(60), r.nextInt(20), r.nextInt(60), r.nextInt(20));
g.setColor(Color.green);
g.drawLine(r.nextInt(60), r.nextInt(20), r.nextInt(60), r.nextInt(20));
g.dispose();
response.setContentType("image/jpeg");
ServletOutputStream sos = response.getOutputStream();
JPEGImageEncoder jpeg = JPEGCodec.createJPEGEncoder(sos);
jpeg.encode(image);
//request.getSession().setAttribute("yzm", new String(ch));

}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { this.doGet(request, response);
}}jsp：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">

    <title>My JSP 'yzm.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

<script></script>
  </head>

  <body>
  <form name="form1" method="post" action="" >
    <img width="56" height="29" src="YzmServlet" id="img"></td>
    </form>
  </body>
</html>