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java验证码

2014-05-11 16:04 232 查看

前台调用servlet

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<script type="text/javascript">
function refresh(obj) {
obj.src = "RandomImg?" + Math.random();
}
</script>
</head>

<body>
<jsp:include page="header.jsp"></jsp:include>
<form action="LoginServlet" method="post">

<table align="center">
<tr>
<td>
用户名
</td>
<td width="150px">
<input type="text" name="username" value="${loginForm.username}"/>
</td>
<td>${loginForm.errors.username}</td>

</tr>
<tr>
<td>
密码
</td>
<td width="150px">
<input type="password" name="password" />
</td><td>${loginForm.errors.password}</td>
</tr>

<tr>
<td>
输入验证码
</td>
<td width="60px">
<input type="text" name="randomCode" width="60px" />
</td>
<td>
<img title="点击更换" alt="验证码" src="RandomImg"
onclick="javascript:refresh(this);">
</td>
</tr>
<tr>
<td colspan="3" align="center">
<input type="submit" value="登录" />
<input type="reset"value="重置" />
</td>
</tr>
</table>

</form>
<jsp:include page="footer.jsp"></jsp:include>
</body>
</html>

RandomImg具体实现如下

package cn.itcast.bbs.controller;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.itcast.bbs.util.RandomValidateCode;

public class RandomImg extends HttpServlet {

private static final long serialVersionUID = 1L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg");// 设置响应类型，告诉浏览器输出的是图片
response.setHeader("Pragma", "No-cache");// 设置响应头，不缓存
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Exprie", 0);
RandomValidateCode randomVlidateCode = new RandomValidateCode();
try {
randomVlidateCode.getRandomcode(request, response);// 输出图片
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGet(req, resp);
}

}

randomVlidateCode方法的具体实现如下

package cn.itcast.bbs.util;

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.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class RandomValidateCode {

public static final String RANDOMCODEKEY = "RANDOMALLDATEKEY";// 放到session中的key
private Random random = new Random();
private String randomString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
private int width = 80;// 图片宽
private int height = 26;// 图片高
private int lineSize = 40;// 干扰线数量
private int stringNum = 4;// 随机产生字符数量

/***
* 获得字体
*
* @return
*/
private Font getFont() {
return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
}

/***
* 获得颜色
*
* @param fc
* @param bc
* @return
*/
private Color getRandColor(int fc, int bc) {
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc - 16);
int g = fc + random.nextInt(bc - fc - 14);
int b = fc + random.nextInt(bc - fc - 18);

return new Color(r, g, b);

}

/***
* 生产随机图片
*
* @param request
* @param response
*/
public void getRandomcode(HttpServletRequest request,
HttpServletResponse response) {

HttpSession session = request.getSession();

// BufferedImage类具有缓冲区的Image类，Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);

Graphics g = image.getGraphics();// 产生image的Graphics 对象，该对象可以对图像进行各种绘制操作
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
g.setColor(getRandColor(110, 133));

// 绘制干扰线
for (int i = 0; i <= lineSize; i++) {
drowLine(g);
}
// 绘制随机字符
String randomString = "";
for (int i = 1; i <= stringNum; i++) {
randomString = drowString(g, randomString, i);
}
session.removeAttribute(RANDOMCODEKEY);
session.setAttribute(RANDOMCODEKEY, randomString);
System.out.println(randomString.toLowerCase());
g.dispose();
try {
ImageIO.write(image, "JPEG", response.getOutputStream());
} catch (IOException e) {

e.printStackTrace();
}

}

/***
* 字符串干扰线
*
* @param g
* @param randomString2
* @param i
* @return
*/
private String drowString(Graphics g, String randomString2, int i) {
g.setFont(getFont());
g.setColor(new Color(random.nextInt(101), random.nextInt(111), random
.nextInt(121)));
String rand = String.valueOf(getRandomString(random
.nextInt(randomString.length())));
randomString2 += rand;
g.translate(random.nextInt(3), random.nextInt(3));
g.drawString(rand, 13 * i, 16);
return randomString2;

}

private String getRandomString(int nextInt) {
return String.valueOf(randomString.charAt(nextInt));
}

/***
* 绘制干扰线
*
* @param g
*/
private void drowLine(Graphics g) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int x1 = random.nextInt(13);
int y1 = random.nextInt(15);
g.drawLine(x, y, x + x1, y + y1);
}

}

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