java 生成图片验证码 工具类

package utils;



import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
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 CodeUtils {
    //得到随机数
    private static char[] chars = "abdefghijkmnpqrstuvwxyABCDEFGHIJKLMNPQRSTUVWXY3456789".toCharArray();
    private static Random random = new Random();
    private static String getCode(int length){
        StringBuffer sb = new StringBuffer();
        for(int i=0;i<length;i++){
            sb.append(chars[random.nextInt(chars.length)]);
        }
        return sb.toString();
    }
    
    /*
     * @说明: 设计验证码并写出图片文件
     */
    public static void createCode(HttpServletRequest req,HttpServletResponse resp){
        try {
            //1.创建画布
            BufferedImage bufferedImage = new BufferedImage(120, 34, BufferedImage.TYPE_INT_RGB);
            //2.创建画笔
            Graphics2D graphics2d = bufferedImage.createGraphics();
            //6.设置背景颜色  ， 先设置画笔颜色  ，在把画布涂满
            graphics2d.setColor(new Color(249, 250, 108));
            //7.涂满画布
            graphics2d.fillRect(0, 0, 120, 34);
            //8.更新画笔颜色
            graphics2d.setColor(new Color(62, 128, 27));
            //9.设置字体
            graphics2d.setFont(new Font("Dope Crisis", Font.PLAIN, 40));
            String code = getCode(4);
            //12.保存到sesssion中
            HttpSession session=req.getSession();
            session.setAttribute("code", code);
            session.setMaxInactiveInterval(1000);
            //3.写字
            graphics2d.drawString(code, 25,30);
            //4.收笔
            graphics2d.dispose();
            //5.保存到服务器上
            ImageIO.write(bufferedImage, "jpg", resp.getOutputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public static void main(String[] args) throws Exception {
        //1.创建画布
        BufferedImage bufferedImage = new BufferedImage(120, 34, BufferedImage.TYPE_INT_RGB);
        //2.创建画笔
        Graphics2D graphics2d = bufferedImage.createGraphics();
        //6.设置背景颜色  ， 先设置画笔颜色  ，在把画布涂满
        graphics2d.setColor(new Color(20, 123, 228));
        //7.涂满画布
        graphics2d.fillRect(0, 0, 120, 34);
        //8.更新画笔颜色
        graphics2d.setColor(new Color(246, 129, 50));
        //9.设置字体
        graphics2d.setFont(new Font("Dope Crisis", Font.PLAIN, 40));
        String num = getCode(4);
        //3.写字
        graphics2d.drawString(num, 25,30);
        //4.收笔
        graphics2d.dispose();
        //5.保存到硬盘上
        ImageIO.write(bufferedImage, "jpg", new File("c:\abc.jpg"));
    }
    //11.保存到服务器上
}