java生成验证码

package com.ay.framework.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;

/**
 * 随机认证码的Util工具类
 * 
 * @author PS
 * 
 */
@SuppressWarnings("all")
public class RandomNumUtil {

    /** 图像 */
    private ByteArrayInputStream image;
    /** 验证码 */
    private String str="";

    private RandomNumUtil() {
        init(); // 初始化属性
    }

    /**
     * 取得randomNumUtil 新的实例
     * 
     * @return
     */
    public static RandomNumUtil Instance() {
        return new RandomNumUtil();
    }

    /**
     * 创建方法
     */
    private void init() {
        String numberStr=SystemParameter.getLogin_authcode_digit();
        String typeStr=SystemParameter.getLogin_authcode_type();
        int number = Integer.parseInt(numberStr);
        int type = Integer.parseInt(typeStr);
        // 在内存中创建图像
        int width = 85, height = 20;
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        Graphics g = image.getGraphics();
        // 生成随机类
        Random random = new Random();
        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);
        // 设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));

        for (int i = 0; i < 155; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }
        // 取随机产生的认证码(6位数字)
        String sRand = "";
        for (int i = 0; i < number; i++) {
            String rand = null;
            switch (type) {
            case 0://数字
                rand = String.valueOf(random.nextInt(10));
                break;
            case 1://字母
                char ca1;
                if(random.nextInt(2)==0){
                    //大写字母
                    ca1 = (char)(random.nextInt(26)+65);
                }else{
                    //小写字母
                    ca1 = (char)(random.nextInt(26)+97);
                }
                rand = String.valueOf(ca1);
                break;
            case 2://混合             
                if(random.nextInt(2)==0){
                    char ca;
                    if(random.nextInt(2)==0){
                        //大写字母
                        ca = (char)(random.nextInt(26)+65);
                    }else{
                        //小写字母
                        ca = (char)(random.nextInt(26)+97);
                    }
                    rand = String.valueOf(ca);
                }else
                    rand = String.valueOf(random.nextInt(10));
                break;
            default:
                rand = String.valueOf(random.nextInt(10));
                break;
            }
            
            sRand += rand;
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110), 20 + random
                    .nextInt(110), 20 + random.nextInt(110)));
            // 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.drawString(rand, 13 * i + 6, 16);
            /** 赋值验证码 */
            this.str += rand;
        }
        // 图象生效
        g.dispose();
        ByteArrayInputStream input = null;
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        try {
            ImageOutputStream imageOut = ImageIO
                    .createImageOutputStream(output);
            ImageIO.write(image, "JPEG", imageOut);
            imageOut.close();
            input = new ByteArrayInputStream(output.toByteArray());
        } catch (Exception e) {
            System.out.println("验证码图片产生出现错误：" + e.toString());
        }
        /** 赋值图像 */
        this.image = input;
    }

    /**
     * 取得验证码图片
     * 
     * @return
     */
    public ByteArrayInputStream getImage() {
        return this.image;
    }

    /**
     * 取得图片的验证码
     * 
     * @return
     */
    public String getString() {
        return this.str;
    }

    private Color getRandColor(int fc, int bc) {
        Random random = new Random();
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }
}