import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
/*
 * 步骤：
 * 1.画框
 * 2.画背景
 * 3.画字符
 * 4.画干扰线
 */
public final class ImageUtil {
   
  // 验证码字符集
  private static final char[] chars = { 
    \'0\', \'1\', \'2\', \'3\', \'4\', \'5\', \'6\', \'7\', \'8\', \'9\', 
    \'A\', \'B\', \'C\', \'D\', \'E\', \'F\', \'G\', \'H\', \'I\', \'J\', \'K\', \'L\', \'M\', \'N\', 
    \'O\', \'P\', \'Q\', \'R\', \'S\', \'T\', \'U\', \'V\', \'W\', \'X\', \'Y\', \'Z\'};
  // 字符数量
  private static final int SIZE = 4;
  // 干扰线数量
  private static final int LINES = 5;
  // 宽度
  private static final int WIDTH = 80;
  // 高度
  private static final int HEIGHT = 40;
  // 字体大小
  private static final int FONT_SIZE = 30;
 
  /**
   * 生成随机验证码及图片
   * Object[0]验证码字符串String
   * Object[1]验证码图片  BufferedImage
   */
  public static Object[] createImage() {
    StringBuffer sb = new StringBuffer();
    // 1.创建空白图片
    BufferedImage image = new BufferedImage(
      WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
    // 2.获取图片画笔
    Graphics graphic = image.getGraphics();
    // 3.设置画笔颜色
    graphic.setColor(Color.LIGHT_GRAY);
    // 4.绘制矩形背景
    graphic.fillRect(0, 0, WIDTH, HEIGHT);
    // 5.画随机字符
    Random ran = new Random();
    for (int i = 0; i <SIZE; i++) {
      // 取随机字符索引
      int n = ran.nextInt(chars.length);
      // 设置随机颜色
      graphic.setColor(getRandomColor());
      // 设置字体大小
      graphic.setFont(new Font(
        null, Font.BOLD + Font.ITALIC, FONT_SIZE));
      // 画字符
      graphic.drawString(
        chars[n] + \"\", i * WIDTH / SIZE, HEIGHT / 2);
      // 记录字符
      sb.append(chars[n]);
    }
    // 6.画干扰线
    for (int i = 0; i < LINES; i++) {
      // 设置随机颜色
      graphic.setColor(getRandomColor());
      // 随机画线
      graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT),
          ran.nextInt(WIDTH), ran.nextInt(HEIGHT));
    }
    // 7.返回验证码和图片
    return new Object[]{sb.toString(), image};
  }
 
  /**
   * 随机取色
   */
  public static Color getRandomColor() {
    Random ran = new Random();
    Color color = new Color(ran.nextInt(256), 
        ran.nextInt(256), ran.nextInt(256));
    return color;
  }
   
  public static void main(String[] args) throws IOException {
    Object[] objs = createImage();
    BufferedImage image = (BufferedImage) objs[1];
    //图片格式可以自定义，java对png图片显示更清楚，输出路径可自定义
    OutputStream os = new FileOutputStream(\"d:/x.png\");
    //注意图片格式与创建格式匹配
    ImageIO.write(image, \"png\", os);
    os.close();
  }
 
}