简单验证码的生成和使用
我们可以先定义一个servlet：因为我们要把生成都验证码保存到session里面，在servlet里面较方便当然也可以在jsp里面生成。
package com.zchen.util;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;
import javax.imageio.*;
public class AuthImg extends HttpServlet
{
//定义图形验证码中绘制字符的字体
private final Font mFont =
new Font("Arial Black", Font.PLAIN, 16);
//定义图形验证码的大小
private final int IMG_WIDTH = 100;
private final int IMG_HEIGTH = 18;
//定义一个获取随机颜色的方法
private Color getRandColor(int fc,int bc)
{
Random random = new Random();
if(fc > 255) fc = 255;
if(bc > 255) bc=255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
//得到随机颜色
return new Color(r , g , b);
}
//重写service方法，生成对客户端的响应
public void service(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException
{
//设置禁止缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
BufferedImage image = new BufferedImage
(IMG_WIDTH , IMG_HEIGTH , BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200 , 250));
//填充背景色
g.fillRect(1, 1, IMG_WIDTH - 1, IMG_HEIGTH - 1);
//为图形验证码绘制边框
g.setColor(new Color(102 , 102 , 102));
g.drawRect(0, 0, IMG_WIDTH - 1, IMG_HEIGTH - 1);
g.setColor(getRandColor(160,200));
//生成随机干扰线
for (int i = 0 ; i < 80 ; i++)
{
int x = random.nextInt(IMG_WIDTH - 1);
int y = random.nextInt(IMG_HEIGTH - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g.drawLine(x , y , x + xl , y + yl);
}
g.setColor(getRandColor(160,200));
//生成随机干扰线
for (int i = 0 ; i < 80 ; i++)
{
int x = random.nextInt(IMG_WIDTH - 1);
int y = random.nextInt(IMG_HEIGTH - 1);
int xl = random.nextInt(12) + 1;
int yl = random.nextInt(6) + 1;
g.drawLine(x , y , x - xl , y - yl);
}
//设置绘制字符的字体
g.setFont(mFont);
//用于保存系统生成的随机字符串
String sRand = "";
for (int i = 0 ; i < 6 ; i++)
{
String tmp = getRandomChar();
sRand += tmp;
//获取随机颜色
g.setColor(new Color(20 + random.nextInt(110)
,20 + random.nextInt(110)
,20 + random.nextInt(110)));
//在图片上绘制系统生成的随机字符
g.drawString(tmp , 15 * i + 10,15);
}
//获取HttpSesssion对象
HttpSession session = request.getSession(true);
//将随机字符串放入HttpSesssion对象中
session.setAttribute("rand" , sRand);
g.dispose();
//向输出流中输出图片
ImageIO.write(image, "JPEG", response.getOutputStream());
}
//定义获取随机字符串方法
private String getRandomChar()
{
//生成一个0、1、2的随机数字
int rand = (int)Math.round(Math.random() * 2);
long itmp = 0;
char ctmp = '\u0000';
switch (rand)
{
//生成大写字母
case 1:
itmp = Math.round(Math.random() * 25 + 65);
ctmp = (char)itmp;
return String.valueOf(ctmp);
//生成小写字母
case 2:
itmp = Math.round(Math.random() * 25 + 97);
ctmp = (char)itmp;
return String.valueOf(ctmp);
//生成数字
default :
itmp = Math.round(Math.random() * 9);
return itmp + "";
}
}
}
2.创建一个jsp文件定义一个表单。
<body>
<form action="servlet/YanZheng" method="post">
验证码：<input type="text" name="yanzhengma">
<img name="d" src="<%=basePath %>/servlet/AuthImg">
<input type="submit">
</form>
</body>
</body>
说明：input标签就是我们输入的验证码。<img >标签就是servlet自动帮我们生成的图形验证码。
但我们怎么讲验证码显示出来呢？
当创建AuthImg servlet的时候eclipse会自动帮我们在web.xml文件中配置映射路径所以<img src="--">就是这个路径。
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>AuthImg</servlet-name>
<servlet-class>com.zchen.util.AuthImg</servlet-class>
</servlet>
<servlet>
<servlet-name>YanZheng</servlet-name>
<servlet-class>com.zchen.util.YanZheng</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AuthImg</servlet-name>
<url-pattern>/servlet/AuthImg</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>YanZheng</servlet-name>
<url-pattern>/servlet/YanZheng</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>/index.jsp</welcome-file>
</welcome-file-list>
</web-app>
3.在YanZheng servlet里面取值:
1>取得自动生成的图形码：(String)request.getSession().getAttribute("rand");
2>取得我们输入的验证码：(String)request.getParameter("yanzhengma");
判断即可;