EasyCaptcha/src/main/java/com/wf/captcha/SpecCaptcha.java

package com.wf.captcha;

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;

import javax.imageio.ImageIO;

/**
 * png格式验证码
 * Created by 王帆 on 2018-07-27 上午 10:08.
 */
public class SpecCaptcha extends Captcha {

    public SpecCaptcha() {
    }

    public SpecCaptcha(int width, int height) {
        setWidth(width);
        setHeight(height);
    }

    public SpecCaptcha(int width, int height, int len) {
        this(width, height);
        setLen(len);
    }

    public SpecCaptcha(int width, int height, int len, Font font) {
        this(width, height, len);
        setFont(font);
    }

    /**
     * 生成验证码
     *
     * @param out 输出流
     * @return 是否成功
     */
    @Override
    public boolean out(OutputStream out) {
        checkAlpha();
        return graphicsImage(textChar(), out);
    }

    /**
     * 生成验证码图形
     *
     * @param strs 验证码
     * @param out  输出流
     * @return boolean
     */
    private boolean graphicsImage(char[] strs, OutputStream out) {
        boolean ok;
        try {
            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);
            // 随机画干扰的圆圈
            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));
                color = null;
            }
            g.setFont(font);
            int h = height - ((height - font.getSize()) >> 1);
            int w = width / len;
            int size = w - font.getSize() + 1;
            // 画字符串
            for (int i = 0; i < len; i++) {
                ac3 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.7f);// 指定透明度
                g.setComposite(ac3);
                color = new Color(20 + num(110), 20 + num(110), 20 + num(110));// 对每个字符都用随机颜色
                g.setColor(color);
                g.drawString(String.valueOf(strs[i]), (width - (len - i) * w) + size, h - 4);
                color = null;
                ac3 = null;
            }
            ImageIO.write(bi, "png", out);
            out.flush();
            ok = true;
        } catch (IOException e) {
            ok = false;
            e.printStackTrace();
        } finally {
            try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return ok;
    }
}