import java.awt.Color;  import java.awt.Font;  import java.awt.Graphics;  import java.awt.image.BufferedImage;  import java.util.HashMap;  import java.util.Map;  import java.util.Random;     //验证码  public final class ImageUtil {      private static final String[] chars = { "0", "1", "2", "3", "4", "5", "6",              "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "J", "K",              "L", "M", "N", "P" };      private static final int SIZE = 5;// 字符长度      private static final int LINES = 7;// 干扰线      private static final int WIDTH = 100;      private static final int HEIGHT = 50;      private static final int FONT_SIZE = 30;// 字体大小         public static Map<String, BufferedImage> createImage() {          StringBuffer sb = new StringBuffer();          BufferedImage image = new BufferedImage(WIDTH, HEIGHT,                  BufferedImage.TYPE_INT_RGB);          Graphics graphic = image.getGraphics();          graphic.setColor(Color.LIGHT_GRAY);          graphic.fillRect(0, 0, WIDTH, HEIGHT);          Random ran = new Random();          // 画随机字符          for (int i = 1; i <= SIZE; i++) {                 int r = ran.nextInt(chars.length);              graphic.setColor(getRandomColor());              graphic.setFont(new Font(null, Font.BOLD + Font.ITALIC, FONT_SIZE));              graphic.drawString(chars[r], (i - 1) * WIDTH / SIZE, HEIGHT / 2);              sb.append(chars[r]);// 将字符保存，存入Session          }          // 画干扰线          for (int i = 1; i <= LINES; i++) {              graphic.setColor(getRandomColor());              graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT),                      ran.nextInt(WIDTH), ran.nextInt(HEIGHT));          }          Map<String, BufferedImage> map = new HashMap<String, BufferedImage>();          map.put(sb.toString(), image);          return map;      }         public static Color getRandomColor() {          Random ran = new Random();          Color color = new Color(ran.nextInt(156), ran.nextInt(156),                  ran.nextInt(156));          return color;      }  }