验证码图片生成工具类——Captcha.java

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
* 验证码图片生成工具
*  使用JAVA生成的图片验证码，调用getRandcode方法获取图片验证码，以流的方式传输到前端页面。
*
*
* 作者: zhoubang
* 日期：2015年8月7日 上午10:41:05
*/
public class Captcha {

public static final String RANDOMCODEKEY = "sess_captcha";// 放到session中的key
private Random random = new Random();
private String randString = "0123456789";// 随机产生的字符串

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

/*
* 获得颜色
*/
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);
}

/*
* 绘制字符串
*/
private String drowString(Graphics g, String randomString, 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(randString.length())));
randomString += rand;
g.translate(random.nextInt(3), random.nextInt(3));
g.drawString(rand, 13 * i, 16);
return randomString;
}

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

/*
* 获取随机的字符
*/
public String getRandomString(int num) {
return String.valueOf(randString.charAt(num));
}

/**
* 生成随机图片
*/
public void getRandcode(HttpServletRequest request, HttpServletResponse response) {
HttpSession session = request.getSession();
// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
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);
g.dispose();
try {
ImageIO.write(image, "JPEG", response.getOutputStream());// 将内存中的图片通过流动形式输出到客户端
} catch (Exception e) {
e.printStackTrace();
}
}
}

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(description = "图片验证码生成", urlPatterns = { "/ImageServlet" })
public class ImageServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public ImageServlet() {
super();
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("image/jpeg");// 设置相应类型,告诉浏览器输出的内容为图片
response.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expire", 0);
Captcha randomValidateCode = new Captcha();
try {
randomValidateCode.getRandcode(request, response);// 输出图片方法
} catch (Exception e) {
e.printStackTrace();
}
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}