验证码

 

import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.GraphicsEnvironment;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

/**
 * 验证图片的返回
 * 
 * @author Vernon.Chen
 * 
 */
public class VerifyCodeAction extends ActionSupport {
	private static int LENGTH = 4; // 控制验证码的长度

	/**
	 * 生成图片
	 * 
	 * @param code
	 *            验证码组合
	 * @return
	 */
	private BufferedImage getImage(String code) {
		List<String> fonts = new ArrayList<String>();
		GraphicsEnvironment.getLocalGraphicsEnvironment().preferLocaleFonts();
		String[] names = GraphicsEnvironment.getLocalGraphicsEnvironment()
				.getAvailableFontFamilyNames(Locale.ENGLISH);
		for (String s : names) {
			char c = s.charAt(0);
			if (Character.isLowerCase(c) || Character.isUpperCase(c)) {

			} else {
				fonts.add(s);
			}
		}
		if (fonts.size() == 0) {
			names = GraphicsEnvironment.getLocalGraphicsEnvironment()
					.getAvailableFontFamilyNames(Locale.CHINA);
			for (String s : names) {
				char c = s.charAt(0);
				if (Character.isLowerCase(c) || Character.isUpperCase(c)) {

				} else {
					fonts.add(s);
				}
			}
		}

		int w = 25 * LENGTH;
		int h = 30;
		BufferedImage image = new BufferedImage(w, h,
				BufferedImage.TYPE_INT_RGB);
		try {
			Graphics2D g = image.createGraphics();
			char[] use = new char[LENGTH];
			// g.setColor(new Color(240,240,240));
			// g.setBackground(new Color((int) (Math.random() * 256));
			g.fillRect(0, 0, w, h);
			for (int i = 0; i < LENGTH; i++) {
				Point p = new Point(
						1 + (i * ((int) (Math.random() * 10) + (int) w / 5)),
						h - 5);
				int size = 0;
				int[] sizes = new int[15];
				for (int j = 0; j < 15; j++) {
					sizes[j] = 15 + j;
				}
				size = sizes[(int) (Math.random() * sizes.length)];
				int face = 0;
				if (Math.random() * 10 > 5) {
					face = Font.BOLD;
				} else {
					face = Font.ITALIC;
				}
				use[i] = code.charAt(i);
				g.setPaint(new GradientPaint(p.x, p.y, new Color((int) (Math
						.random() * 256), 0, (int) (Math.random() * 256)), p.x,
						p.y - size, new Color((int) (Math.random() * 256),
								(int) (Math.random() * 256), (int) (Math
										.random() * 256))));
				if (fonts.size() > 0) {
					g.setFont(new Font(fonts.get((int) (Math.random() * fonts
							.size())), face, size));
				} else {
					g.setFont(null);

				}
				g.drawString("" + use[i], p.x, p.y);
			}
			g.setPaint(null);
			for (int i = 0; i < 6; i++) {
				g.setColor(new Color((int) (Math.random() * 0x00FFFFFFF)));
				g.drawLine((int) (Math.random() * w),
						(int) (Math.random() * h), (int) (Math.random() * w),
						(int) (Math.random() * h));
			}
			g.dispose();
		} catch (Exception e) {
			e.printStackTrace();
		}
		image.flush();
		return image;
	}

	public String verifyCode() throws Exception {
		// 生成随机类
		Random random = new Random();

		// 取随机产生的认证码(LENGTH位数字)
		String sRand = "";
		for (int i = 0; i < LENGTH; i++) {
			String rand = String.valueOf(random.nextInt(10));
			sRand += rand;
		}

		BufferedImage image = getImage(sRand);

		HttpServletResponse response = ServletActionContext.getResponse();
		response.setContentType("image/jpg");
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		ServletOutputStream out = response.getOutputStream();
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		ImageIO.write(image, "JPEG", baos);
		byte[] buffer = baos.toByteArray();
		response.setContentLength(buffer.length);

		out.write(buffer);
		out.close();
		return null;
	}

}
验证码测试:<br/>	<img alt="验证码"  src="/wenda/verifyCodeAction!verifyCode.action" />