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java使用servlet实现验证码

2017-01-05 11:41 555 查看

利用servlet 实现验证码主要继承httpServlet类

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 + "";
}
}
}

下面是web.xml 配置

<?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>

jsp 文件

<%@ 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>

简单实用。

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标签： java servlet 验证码

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