import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Random;
import javax.imageio.ImageIO;
 
public class ValidationCode {
 
    // 图形验证码的字符集合，系统将随机从这个字符串中选择一些字符作为验证码
    private static String codeChars = "%#23456789abcdefghkmnpqrstuvwxyzABCDEFGHKLMNPQRSTUVWXYZ";
 
    // 返回一个随机颜色（Color对象）
    private static Color getRandomColor(int minColor, int maxColor) {
        Random random = new Random();
        // 保存minColor最大不会超过255
        if (minColor > 255)
            minColor = 255;
        // 保存minColor最大不会超过255
        if (maxColor > 255)
            maxColor = 255;
        // 获得红色的随机颜色值
        int red = minColor + random.nextInt(maxColor - minColor);
        // 获得绿色的随机颜色值
        int green = minColor + random.nextInt(maxColor - minColor);
        // 获得蓝色的随机颜色值
        int blue = minColor + random.nextInt(maxColor - minColor);
        return new Color(red, green, blue);
    }
 
    protected static void getValidationCode() throws IOException {
        try {
            // 获得验证码集合的长度
            int charsLength = codeChars.length();
            // 设置图形验证码的长和宽（图形的大小）
            int width = 90, height = 30;
            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            Graphics g = image.getGraphics();// 获得用于输出文字的Graphics对象
            Random random = new Random();
            g.setColor(getRandomColor(180, 250));// 随机设置要填充的颜色
            g.fillRect(0, 0, width, height);// 填充图形背景
            // 设置初始字体
            g.setFont(new Font("Times New Roman", Font.ITALIC, height));
            g.setColor(getRandomColor(120, 180));// 随机设置字体颜色
            // 用于保存最后随机生成的验证码
            StringBuilder validationCode = new StringBuilder();
            // 验证码的随机字体
            String[] fontNames = { "Times New Roman", "Book antiqua", "Arial" };
            // 随机生成3个到5个验证码
            for (int i = 0; i < 3 + random.nextInt(3); i++) {
                // 随机设置当前验证码的字符的字体
                g.setFont(new Font(fontNames[random.nextInt(3)], Font.ITALIC, height));
                // 随机获得当前验证码的字符
                char codeChar = codeChars.charAt(random.nextInt(charsLength));
                validationCode.append(codeChar);
                // 随机设置当前验证码字符的颜色
                g.setColor(getRandomColor(10, 100));
                // 在图形上输出验证码字符，x和y都是随机生成的
                g.drawString(String.valueOf(codeChar), 16 * i + random.nextInt(7), height - random.nextInt(6));
            }
            File file = new File("d:\\code.png");  
            ImageIO.write(image, "png", file);  
            System.out.println(validationCode.toString());
            //byte[] data = ((DataBufferByte) image.getData().getDataBuffer()).getData();
            g.dispose();
        } catch (Exception e) {
            e.printStackTrace();  
        }
    }
 
    public static void main(String[] args) throws IOException{
        getValidationCode();
    }
}