java 验证码类_Java 验证码工具类

package com.wuyu.util;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.Graphics2D;

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.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

* 验证码工具类

* @author wuyu

*/

public class ValidateCode {

public static final int WIDTH = 93;

public static final int HEIGHT = 30;

public static String getImageCode(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=utf-8");

// 创建缓存

BufferedImage bi = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);

// 获得画布

Graphics g = bi.getGraphics();

// 设置背影色

setBackGround(g);

// 设置边框

setBorder(g);

// 写随机数

String random = drawRandomNum((Graphics2D) g);

// 将随机汉字存在session中

// request.getSession().setAttribute("checkcode", random);

// 将图形写给浏览器

response.setContentType("image/jpeg");

// 发头控制浏览器不要缓存

response.setDateHeader("expries", -1);

response.setHeader("Cache-Control", "no-cache");

response.setHeader("Pragma", "no-cache");

// 将图片写给浏览器

ImageIO.write(bi, "jpg", response.getOutputStream());

return random;

}

/**

* 设置背景色

*

* @param g

*/

private static void setBackGround(Graphics g) {

// 设置颜色

g.setColor(Color.WHITE);

// 填充区域

g.fillRect(0, 0, WIDTH, HEIGHT);

}

/**

* 设置边框

*

* @param g

*/

private static void setBorder(Graphics g) {

// 边框区域

g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);

}

/**

*

* @param g

* @return

*/

private static String drawRandomNum(Graphics2D g) {

StringBuffer sb = new StringBuffer();

// 设置颜色

g.setColor(Color.RED);

String[] code = { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s",

"t", "u", "v", "w", "x", "y", "z", "1", "2", "3", "4", "5", "6", "7", "8", "9", "0" };

int x = 7;

g.setFont(new Font("DEFAULT", Font.PLAIN, 24));

// 控制字符数

Random random = new Random();

for (int i = 0; i < 4; i++) {

// 设置字体旋转角度

int degree = new Random().nextInt() % 30;

// 截取\

String ch = code[random.nextInt(code.length)];

sb.append(ch);

// 正向角度

g.rotate(degree * Math.PI / 180, x, 20);

g.drawString(ch, x, 20);

// 反向角度

g.rotate(-degree * Math.PI / 180, x, 20);

x += 20;

}

return sb.toString();

}

}