linux可用验证码

package org.xx.xxxx;


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

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

/**
 * 验证码相关的action
 * 
 * @author i++
 * 
 */
public class ValidateCodeAction extends HttpServlet {


	private static final long serialVersionUID = 1L;

	public String random(int count, int start, int end, boolean letters,
			boolean numbers, char set[]) {

		Random RANDOM = new Random();
		if (start == 0 && end == 0) {
			end = 122;
			start = 32;
			if (!letters && !numbers) {
				start = 0;
				end = 0x7fffffff;
			}
		}
		StringBuffer buffer = new StringBuffer();
		int gap = end - start;
		while (count-- != 0) {
			char ch;
			if (set == null)
				ch = (char) (RANDOM.nextInt(gap) + start);
			else
				ch = set[RANDOM.nextInt(gap) + start];
			if (letters && numbers && Character.isLetterOrDigit(ch) || letters
					&& Character.isLetter(ch) || numbers
					&& Character.isDigit(ch) || !letters && !numbers)
				buffer.append(ch);
			else
				count++;
		}
		return buffer.toString();
	}

	// RandomStringUtils rs=new RandomStringUtils();
	// String random=rs.randomAlphanumeric(4);
	// String random = random(4,65, 90,false,false,null);

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

	
		String random = random(4, 48, 57, false, false, null);
		HttpSession session = request.getSession();
		session.setAttribute("TOKEN", random);
		response.setContentType("image/gif");
		response.addHeader("pragma", "NO-cache");
		response.addHeader("Cache-Control", "no-cache");
		response.addDateHeader("Expries", 0);
		// int width=100, height=40;
		// int width=75, height=25;
		int width = 52, height = 22;
		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();

		// 以下填充背景颜色
		// g.setColor(Color.GRAY);
		g.setColor(Color.WHITE);
		// g.setColor(new Color(255,247,231));
		// g.setColor(new Color(221,238,247));
		// Font DeFont=new Font("SansSerif", Font.PLAIN, 32);
		Font DeFont = new Font("SansSerif", Font.BOLD, 20);
		g.setFont(DeFont);
		g.fillRect(0, 0, width, height);

		// 设置字体颜色
		// g.setColor(Color.RED);
		g.setColor(Color.BLACK);
		// g.drawString(random,3,30);
		g.drawString(random, 2, 18);

		// 随机产生40个干扰点，使图象中的认证码不易被其它程序探测到
		Random ran = new Random();
		for (int i = 0; i < 200; i++) {
			int x = ran.nextInt(width);
			int y = ran.nextInt(height);
			g.drawOval(x, y, 0, 0);
			g.setColor(new Color(196, 163, 161));
		}

		g.dispose();
		ServletOutputStream outStream = response.getOutputStream();
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(outStream);
		encoder.encode(image);
		outStream.close();
	}
	
}