图片验证码

package cn.response;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@SuppressWarnings("serial")
public class validatePicture extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		try {
			validateimage(request, response);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

	public static final int WIDTH = 120;
	public static final int HEIGHT = 25;

	public void validateimage(HttpServletRequest request,
			HttpServletResponse response) throws Exception {

		BufferedImage bi = new BufferedImage(WIDTH, HEIGHT,
				BufferedImage.TYPE_INT_RGB);// 在内存中构建一幅图象
		Graphics g = bi.getGraphics();

		setBackGround(g);// 设置背景色
		setBorder(g);// 设置边框
		drawRandomLine(g);// 画干扰线
		String random = drawRandomNum((Graphics2D) g);// 写随机数

		request.getSession().setAttribute("random", random);
		//request.getSession(false);
		response.setContentType("image/jpeg");
		// 设置不要缓存
		response.setDateHeader("expries", -1);
		response.setHeader("Cache-Control", "no-cache");

		ImageIO.write(bi, "jpg", response.getOutputStream());
	}

	private String drawRandomNum(Graphics2D g) {
		g.setColor(Color.RED);
		g.setFont(new Font("宋体", Font.BOLD, 20));
		// [\u4e00-\u9fa5]中文数字区间
		String base = "\u4e00\u4f00\u5e00\u4e50\u4e89\u4f10\u4e09";

		StringBuffer sb = new StringBuffer();

		int x = 5;
		for (int i = 0; i < 4; i++) {
			int degree = new Random().nextInt() % 30;

			String ch = base.charAt(new Random().nextInt(base.length())) + "";
			sb.append(ch);
			g.rotate(degree * Math.PI / 180, x, 20);
			g.drawString(ch, x, 20);
			g.rotate(-degree * Math.PI / 180, x, 20);

			x = x + 30;
		}
		System.out.println(sb.toString());
		return sb.toString();
	}

	private void drawRandomLine(Graphics g) {
		g.setColor(Color.GREEN);
		for (int i = 0; i < 3; i++) {
			int x1 = new Random().nextInt(WIDTH);
			int y1 = new Random().nextInt(HEIGHT);

			int x2 = new Random().nextInt(WIDTH);
			int y2 = new Random().nextInt(HEIGHT);

			g.drawLine(x1, y1, x2, y2);
		}
	}

	private void setBorder(Graphics g) {
		g.setColor(Color.BLUE);
		g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
	}

	private void setBackGround(Graphics g) {
		g.setColor(Color.WHITE);
		g.fillRect(0, 0, WIDTH, HEIGHT);
	}
}