CaptchaUtil.java

package com.opslab.util.image;

import com.opslab.util.image.GIF.GifEncoder;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

/**
 * 具体用于实现生成验证码图片的方法
 */
public final class CaptchaUtil {
    protected static Font font = new Font("Verdana", Font.ITALIC|Font.BOLD, 28);   // 字体
    /**
     * 产生0--num的随机数,不包括num
     * @param num 数字
     * @return int 随机数字
     */
    public static int num(int num)
    {
        return (new Random()).nextInt(num);
    }
    /**
     * 给定范围获得随机颜色
     * @return Color 随机颜色
     */
    protected static Color color(int fc, int bc)
    {
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + num(bc - fc);
        int g = fc + num(bc - fc);
        int b = fc + num(bc - fc);
        return new Color(r, g, b);
    }


    public static boolean pngCaptcha(String randomStr,int width,int height,String file){
        char[] strs = randomStr.toCharArray();
        try(OutputStream out = new FileOutputStream(file))
        {
            BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
            Graphics2D g = (Graphics2D)bi.getGraphics();
            AlphaComposite ac3;
            Color color ;
            int len = strs.length;
            g.setColor(Color.WHITE);
            g.fillRect(0,0,width,height);
            for(int i=0;i<15;i++){
                color = color(150, 250);
                g.setColor(color);
                g.drawOval(num(width), num(height), 5+num(10), 5+num(10));
            }
            g.setFont(font);
            int h  = height - ((height - font.getSize()) >>1),
                    w = width/len,
                    size = w-font.getSize()+1;
            for(int i=0;i<len;i++){
                // 指定透明度
                ac3 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.7f);
                g.setComposite(ac3);
                // 对每个字符都用随机颜色
                color = new Color(20 + num(110), 30 + num(110), 30 + num(110));
                g.setColor(color);
                g.drawString(strs[i]+"",(width-(len-i)*w)+size, h-4);
            }
            ImageIO.write(bi, "png", out);
            out.flush();
            return true;
        }catch (IOException e){
            return false;
        }
    }

    public static boolean gifCaptcha(String randomStr,int width,int height,String file){
        char[] rands = randomStr.toCharArray();
        int len = rands.length;
        try(OutputStream out = new FileOutputStream(file))
        {
            // gif编码类，这个利用了洋人写的编码类，所有类都在附件中
            GifEncoder gifEncoder = new GifEncoder();
            //生成字符
            gifEncoder.start(out);
            gifEncoder.setQuality(180);
            gifEncoder.setDelay(100);
            gifEncoder.setRepeat(0);
            BufferedImage frame;
            Color fontcolor[]=new Color[len];
            for(int i=0;i<len;i++)
            {
                fontcolor[i]=new Color(20 + num(110), 20 + num(110), 20 + num(110));
            }
            for(int i=0;i<len;i++)
            {
                frame=graphicsImage(fontcolor, rands, i,width,height,len);
                gifEncoder.addFrame(frame);
                frame.flush();
            }
            gifEncoder.finish();
            return true;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * 画随机码图
     * @param fontcolor 随机字体颜色
     * @param strs 字符数组
     * @param flag 透明度使用
     * @return BufferedImage
     */
    private static BufferedImage graphicsImage(Color[] fontcolor,char[] strs,int flag,int width,int height,int len){
        BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
        //或得图形上下文
        //Graphics2D g2d=image.createGraphics();
        Graphics2D g2d = (Graphics2D)image.getGraphics();
        //利用指定颜色填充背景
        g2d.setColor(Color.WHITE);
        g2d.fillRect(0, 0, width, height);
        AlphaComposite ac3;
        int h  = height - ((height - font.getSize()) >>1) ;
        int w = width/len;
        g2d.setFont(font);
        for(int i=0;i<len;i++) {
            ac3 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, getAlpha(flag, i,len));
            g2d.setComposite(ac3);
            g2d.setColor(fontcolor[i]);
            g2d.drawOval(num(width), num(height), 5+num(10), 5+num(10));
            g2d.drawString(strs[i]+"", (width-(len-i)*w)+(w-font.getSize())+1, h-4);
        }
        g2d.dispose();
        return image;
    }

    /**
     * 获取透明度,从0到1,自动计算步长
     * @return float 透明度
     */
    private static float getAlpha(int i,int j,int len) {
        int num = i+j;
        float r = (float)1/len,s = (len+1) * r;
        return num > len ? (num *r - s) : num * r;
    }
}