驗證碼的封裝

package com.estone.servlet;

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

import org.apache.commons.lang3.math.NumberUtils;
import org.apache.commons.lang3.StringUtils;

/**
 * 生成隨機驗證碼
 */
@SuppressWarnings("serial")
public class Image1 extends HttpServlet {

    public static final String VALIDATE_CODE = "validateCode";

    private int w = 70;
    private int h = 26;

    public Image1() {
        super();
    }

    public void destroy() {
        super.destroy();
    }

    public static boolean validate(HttpServletRequest request,
            String validateCode) {
        String code = (String) request.getSession().getAttribute(VALIDATE_CODE);
        return validateCode.toUpperCase().equals(code);
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String validateCode = request.getParameter(VALIDATE_CODE); // AJAX驗證，成功返回true
        if (StringUtils.isNotBlank(validateCode)) {
            response.getOutputStream().print(
                    validate(request, validateCode) ? "true" : "false");
        } else {
            this.doPost(request, response);
        }
    }

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

    private void createImage(HttpServletRequest request,
            HttpServletResponse response) throws IOException {

        response.setHeader("Pragma", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        response.setContentType("image/jpeg");

        /*
         * 得到參數高，寬，都爲數字時，則使用設置高寬，否則使用默認值
         */
        String width = request.getParameter("width");
        String height = request.getParameter("height");
        if (StringUtils.isNumeric(width) && StringUtils.isNumeric(height)) {
            w = NumberUtils.toInt(width);
            h = NumberUtils.toInt(height);
        }

        BufferedImage image = new BufferedImage(w, h,
                BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();

        /*
         * 生成背景
         */
        createBackground(g);

        /*
         * 生成字符
         */
        String s = createCharacter(g);
        request.getSession().setAttribute(VALIDATE_CODE, s);

        g.dispose();
        OutputStream out = response.getOutputStream();
        ImageIO.write(image, "JPEG", out);
        out.close();

    }

    private Color getRandColor(int fc, int bc) {
        int f = fc;
        int b = bc;
        Random random = new Random();
        if (f > 255) {
            f = 255;
        }
        if (b > 255) {
            b = 255;
        }
        return new Color(f + random.nextInt(b - f), f + random.nextInt(b - f),
                f + random.nextInt(b - f));
    }

    private void createBackground(Graphics g) {
        // 填充背景
        g.setColor(getRandColor(220, 250));
        g.fillRect(0, 0, w, h);
        // 加入干擾線條
        for (int i = 0; i < 8; i++) {
            g.setColor(getRandColor(40, 150));
            Random random = new Random();
            int x = random.nextInt(w);
            int y = random.nextInt(h);
            int x1 = random.nextInt(w);
            int y1 = random.nextInt(h);
            g.drawLine(x, y, x1, y1);
        }
    }

    private String createCharacter(Graphics g) {
        char[] codeSeq = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K',
                'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y',
                'Z', '2', '3', '4', '5', '6', '7', '8', '9' };
        String[] fontTypes = { "Arial", "Arial Black", "AvantGarde Bk BT",
                "Calibri" };
        Random random = new Random();
        StringBuilder s = new StringBuilder();
        for (int i = 0; i < 4; i++) {
            String r = String.valueOf(codeSeq[random.nextInt(codeSeq.length)]);// random.nextInt(10));
            g.setColor(new Color(50 + random.nextInt(100), 50 + random
                    .nextInt(100), 50 + random.nextInt(100)));
            g.setFont(new Font(fontTypes[random.nextInt(fontTypes.length)],
                    Font.BOLD, 26));
            g.drawString(r, 15 * i + 5, 19 + random.nextInt(8));
            s.append(r);
        }
        return s.toString();
    }

}