随机验证码

package com.tools;

import java.awt.*;
import java.awt.geom.AffineTransform;
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.*;

/**
*
* @author administrator
*/
public class CheckCode extends HttpServlet {
public CheckCode() {
super();
}

// 获取随机颜色
public Color getRandColor(int s, int e) {
Random random = new Random();
if (s > 255) s = 255;
if (e > 255) e = 255;
int r = s + random.nextInt(e - s);    //随机生成RGB颜色中的r值
int g = s + random.nextInt(e - s);    //随机生成RGB颜色中的g值
int b = s + random.nextInt(e - s);    //随机生成RGB颜色中的b值
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);
// 指定生成的响应是图片
response.setContentType("image/jpeg");
int width = 116;    //指定验证码的宽度
int height = 33;    //指定验证码的高度

BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics(); //获取Graphics类的对象
Random random = new Random(); //实例化一个Random对象
Font mFont = new Font("宋体", Font.BOLD, 22); //通过Font构造字体
g.fillRect(0, 0, width, height); //绘制验证码背景
g.setFont(mFont); //设置字体
g.setColor(getRandColor(180, 200)); //设置颜色
// 画随机的线条
for (int i = 0; i < 100; i++) {
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int x1 = random.nextInt(3) + 1;
int y1 = random.nextInt(6) + 1;
g.drawLine(x, y, x + x1, y + y1); //绘制直线
}
/**************************画一条折线********************************/    
BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);    //创建一个供画笔选择线条粗细的对象
Graphics2D g2d = (Graphics2D) g; //通过Graphics类的对象创建一个Graphics2D类的对象
g2d.setStroke(bs);    //改变线条的粗细
g.setColor(Color.GRAY);    //设置当前颜色为预定义颜色中的灰色
int lineNumber=4;    //指定端点的个数
int[] xPoints=new int[lineNumber]; //定义保存x轴坐标的数组
int[] yPoints=new int[lineNumber]; //定义保存x轴坐标的数组
//通过循环为x轴坐标和y轴坐标的数组赋值
for(int j=0;j<lineNumber;j++){
xPoints[j]=random.nextInt(width - 1);
yPoints[j]=random.nextInt(height - 1);
}
g.drawPolyline(xPoints, yPoints,lineNumber); //绘制折线
/*******************************************************************/
String sRand = "";
// 输出随机的验证文字
for (int i = 0; i < 4; i++) {
char ctmp = (char)(random.nextInt(26) + 65);    //生成A~Z的字母
sRand += ctmp;
Color color = new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110));
g.setColor(color); //设置颜色
/** **随机缩放文字并将文字旋转指定角度* */
// 将文字旋转指定角度
Graphics2D g2d_word = (Graphics2D) g;
AffineTransform trans = new AffineTransform();
trans.rotate(random.nextInt(45) * 3.14 / 180, 22 * i + 8, 7);
// 缩放文字
float scaleSize = random.nextFloat() +0.8f;
if (scaleSize > 1f)    scaleSize = 1f;
trans.scale(scaleSize, scaleSize); //进行缩放
g2d_word.setTransform(trans);
/** ********************* */
g.drawString(String.valueOf(ctmp), width/6 * i+23, height/2);

}
// 将生成的验证码保存到Session中
HttpSession session = request.getSession(true);
session.setAttribute("randCheckCode", sRand);
g.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
}
public void destroy() {
super.destroy();
}

public void init() throws ServletException {
super.init();
}
}