页⾯：
<%@ page language="java" pageEncoding="GB18030"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>⽹上选课系统----登录界⾯</title>
<SCRIPT language=javascript>
function refresh()
{
}
</script>
一体化橡胶道口板<body vlink="red">
<p>
</p>
<p>
</p>
<p>
</p>
<p align="center">
<%
String validateerror=(Attribute("validateerror");
String error=(Attribute("error");
if(validateerror!=null){
%>
<font color="red" class="STYLE11">验证码错误，请重新输⼊</font>
<%}else if(error!=null){ %>
<font color="red" class="STYLE11">你输⼊的⽤户名或密码有误，请重新输⼊</font>
<%} %>
</p>
<form name="loginform" action="loginservlet" method="post">
<table width="330" height="125" border="1" align="center"
bordercolor="#000000" background="image/admin_bg_1.gif">
<tr>
<td>
<span class="STYLE9"> 验证码:</span> <span class="STYLE11"> <input name="validate" type="text"
size="6" maxlength="6"> <img src="authImg" id="authImg" /><a
href="#" onClick="refresh()">换⼀张</a>
</span>
</td>
</tr>
</table>
</form>
</body>
</html>
<servlet-mapping>
<servlet-name>img</servlet-name>
<url-pattern>/authImg</url-pattern>
</servlet-mapping>
</web-app>
AuthImg.java处理类
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;
import javax.imageio.*;
@SuppressWarnings("serial")
public class AuthImg extends HttpServlet
{
private Font mFont = new Font("Arial Black", Font.PLAIN, 16);
public void init() throws ServletException
{
super.init();
}
Color getRandColor(int fc,int bc)
{
Random random = new Random();
if(fc>255) fc=255;
if(bc>255) bc=255;
int r=Int(bc-fc);
int g=Int(bc-fc);
int b=Int(bc-fc);
return new Color(r,g,b);
}
public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
int width=100, height=18;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics g = Graphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(1, 1, width-1, height-1);
g.setColor(new Color(102,102,102));
g.drawRect(0, 0, width-1, height-1);
g.setFont(mFont);
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
int x = Int(width - 1);
int y = Int(height - 1);
int xl = Int(6) + 1;
int yl = Int(12) + 1;
g.drawLine(x,y,x + xl,y + yl);
}
for (int i = 0;i < 70;i++)
{
int x = Int(width - 1);
int y = Int(height - 1);
int xl = Int(12) + 1;
int yl = Int(6) + 1;
g.drawLine(x,y,x - xl,y - yl);
}
String sRand="";
for (int i=0;i<6;i++)
{
String tmp = getRandomChar();
sRand += tmp;
g.setColor(new Color(Int(110),Int(110),Int(110)));于全
液压矫平机g.drawString(tmp,15*i+10,15);
}
HttpSession session = Session(true);
库顶切换阀
session.setAttribute("rand",sRand);
g.dispose();
ImageIO.write(image, "JPEG", OutputStream());
}
private String getRandomChar()
{
int rand = (und(Math.random() * 2);
long itmp = 0;
char ctmp = '/u0000';
switch (rand)
{
case 1:
itmp = und(Math.random() * 25 + 65);
ctmp = (char)itmp;
return String.valueOf(ctmp);
case 2:
itmp = und(Math.random() * 25 + 97);
ctmp = (char)itmp;
return String.valueOf(ctmp);
default :
itmp = und(Math.random() * 9);
return String.valueOf(itmp);
}
向初
}
}
----------------------------------------------------------------------------------------------------------------------⽅法⼆：
作⽤：
为了不让有的⼈恶意的⽤软件登陆
代码：
AuthImg.java
package login;
import java.awt.Color;
import java.awt.Font;
import java.awt.image.BufferedImage;
import java.awt.Graphics;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.imageio.*;
/
**
* ⽣成图形验证码的 Servlet
*
* @author zyl
*
*/
public class AuthImg extends HttpServlet {
// 设置图形验证码中字符串的字体和⼤⼩
private Font mFont = new Font("Arial Black", Font.PLAIN, 16);
带隙基准电压源public void init() throws ServletException {
super.init();
}
/**
* Constructor of the object.
*/
public AuthImg() {
super();
}
// ⽣成随机的颜⾊
Color getRandColor(int fc, int bc) {
Random random = new Random();
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + Int(bc - fc);
int g = fc + Int(bc - fc);
int b = fc + Int(bc - fc);
return new Color(r, g, b);
}
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//阻⽌⽣成的页⾯内容被缓存，保证每次重新⽣成随机验证码
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
//指定图形验证码的⼤⼩
int width = 100,height = 18;
//⽣成⼀张新图⽚
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //在图⽚中绘制内容
Graphics g = Graphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(1, 1, width-1, height-1);
g.setColor(new Color(102,102,103));
g.drawRect(0,0,width-1,height-1);
g.setFont(mFont);
//随机⽣成线条，让图⽚看起来更加杂乱
