利用servlet 实现验证码主要继承httpServlet类
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package com.zyc.demo;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class DrewImage extends HttpServlet{
/**
*
*/
private static final long serialVersionUID = 1505032428319459075L;
private final Font mFont =
new Font( "Arial Black" , Font.PLAIN, 16 );
private final int IMG_WIDTH = 100 ;
private final int IMG_HEIGTH = 18 ;
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);
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" );
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 ));
g.fillRect( 1 , 1 , IMG_WIDTH - 1 , IMG_HEIGTH - 1 );
g.setColor( new Color( 102 , 102 , 102 ));
g.drawRect( 0 , 0 , IMG_WIDTH - 1 , IMG_HEIGTH - 1 );
g.setColor(getRandColor( 160 , 200 ));
for ( int i = 0 ; i < 30 ; 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 ));
for ( int i = 0 ; i < 30 ; 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);
}
g.setFont(mFont);
String sRand = "" ;
for ( int i = 0 ; i < 4 ; i++)
{
String tmp = getRandomChar();
sRand += tmp;
g.setColor( new Color( 20 + random.nextInt( 110 )
, 20 + random.nextInt( 110 )
, 20 + random.nextInt( 110 )));
g.drawString(tmp , 15 * i + 10 , 15 );
}
HttpSession session = request.getSession( true );
session.setAttribute( "rand" , sRand);
// System.out.println("写入session"+sRand);
g.dispose();
ImageIO.write(image, "JPEG" , response.getOutputStream());
}
private String getRandomChar()
{
int rand = ( int )Math.round(Math.random() * 2 );
long itmp = 0 ;
char ctmp = '\u0000' ;
switch (rand)
{
case 1 :
itmp = Math.round(Math.random() * 25 + 65 );
ctmp = ( char )itmp;
return String.valueOf(ctmp);
case 2 :
itmp = Math.round(Math.random() * 25 + 97 );
ctmp = ( char )itmp;
return String.valueOf(ctmp);
default :
itmp = Math.round(Math.random() * 9 );
return itmp + "" ;
}
}
}
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下面是web.xml 配置
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<? xml version = "1.0" encoding = "UTF-8" ?>
< web-app xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xmlns = "http://java.sun.com/xml/ns/javaee" xsi:schemaLocation = "http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id = "WebApp_ID" version = "3.0" >
< display-name >IndustryDemo</ display-name >
< welcome-file-list >
< welcome-file >index.html</ welcome-file >
< welcome-file >index.htm</ welcome-file >
< welcome-file >index.jsp</ welcome-file >
< welcome-file >default.html</ welcome-file >
< welcome-file >default.htm</ welcome-file >
< welcome-file >default.jsp</ welcome-file >
</ welcome-file-list >
< servlet >
< servlet-name >img</ servlet-name >
< servlet-class >com.zyc.demo.DrewImage</ servlet-class >
</ servlet >
< servlet-mapping >
< servlet-name >img</ servlet-name >
< url-pattern >/img.do</ url-pattern >
</ servlet-mapping >
</ web-app >
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jsp 文件
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<%@ 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 'yanzhengma.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" >
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</ head >
< body >
< img alt = "验证码" src = "img.do" > < button onclick = "window.location.reload();" >刷新</ button >
</ body >
</ html >
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简单实用。
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。