javaWeb图片验证码代码

1. [代码]初始粗糙代码

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

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.*;
/**
 * 验证码图片生成Servlet类，直接调用该Servlet即可使用
 * 取值的时候调用session.getAttribute("code")得到生成的值
 * @author <a href="mailto:weijunqiang2010@gmail.com">Ajunboys</a>
 *
 */
@WebServlet("/safecode")
public class SafeCodeImageServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色
        Random random = new Random();

        if (fc > 255)
            fc = 255;

        if (fc < 0)
            fc = 0;

        if (bc > 255)
            bc = 255;

        if (bc < 0)
            bc = 0;

        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);

        return new Color(r, g, b);
    }

    @Override
    protected void service(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // 设置输出
        response.setContentType("image/jpeg");

        int width = 80;
        int height = 30;

        // 产生随机数
        Random r = new Random();
        // 把随机数绘制成图像

        BufferedImage imgbuf = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);// 产生缓冲图像,80宽30高

        Graphics2D g = imgbuf.createGraphics();// 取得缓冲的绘制环境

        // 开始绘制
        g.setColor(getRandColor(200, 250));// 设定背景色
        g.fillRect(0, 0, width, height);// 矩形图

        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));

        for (int i = 0; i < 155; i++) {
            int x = r.nextInt(width);
            int y = r.nextInt(height);
            int xl = r.nextInt(12);
            int yl = r.nextInt(12);

            g.drawLine(x, y, x + xl, y + yl);
        }

        g.setColor(getRandColor(120, 240));

        // 随机产生100个干扰点，使图像中的验证码不易被其他分析程序探测到
        for (int i = 0; i < 100; i++) {
            int x = r.nextInt(width);
            int y = r.nextInt(height);

            g.drawOval(x, y, 0, 0);
        }

        g.setFont(new Font("Times New Roman", Font.PLAIN, 26));

        String scode = "";

        for (int i = 0; i < 4; i++) {
//            String rand = String.valueOf(r.nextInt(10));
            String rand = randomCode();

            scode += rand;

            g.setColor(new Color(20 + r.nextInt(110), 20 + r.nextInt(110),
                    20 + r.nextInt(110)));

            // 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.drawString(rand+" ", (0==i) ? 12 : (12 * (i+1)+5), 23);
        }

        request.getSession().setAttribute("safecode", scode);

        // 输出图像
        ServletOutputStream out = response.getOutputStream();// 得到HTTP的流

        // JPEGCodec.createJPEGEncoder(out);转码
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);// 产生JPEG的图像加码器

        encoder.encode(imgbuf);
        out.flush();
    }

    private static String randomCode(){
        char[] dictionary = {
                '2','3','4','5','6','7','8','9'
                ,'a','b','c','d','e','f','g','h','i','j'
                ,'k','m','n','p','q','r','s','t'
                ,'u','v','w','x','y','z'
                ,'A','B','C','D','E','F','G','H','J'
                ,'K','L','M','N','P','Q','R','S','T'
                ,'U','V','W','X','Y','Z'
                /*'1','l','0','O','o','#','@','$','%','&','(',')','|','/','*'//暂时不用特殊字符(包括：数字1,0；字母：l,o,O)
                ,'^','!','~','\\'*/
                };
        StringBuffer code = new StringBuffer();

        Random r = new Random();

        code.append(dictionary[r.nextInt(dictionary.length)]);

        return code.toString();
    }

}

2. [代码]优化后的全代码

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

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

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

/**
 * 验证码图片生成Servlet类，直接调用该Servlet即可使用
 * 取值的时候调用session.getAttribute("code")得到生成的值
 * @author <a href="mailto:weijunqiang2010@gmail.com">Ajunboys</a>
 *
 */
@WebServlet("/safecode")
public class SafeCodeImageServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    static final char[] dictionary = {
            '2','3','4','5','6','7','8','9'
            ,'a','b','c','d','e','f','g','h','i','j'
            ,'k','m','n','p','q','r','s','t'
            ,'u','v','w','x','y','z'
            ,'A','B','C','D','E','F','G','H','J'
            ,'K','L','M','N','P','Q','R','S','T'
            ,'U','V','W','X','Y','Z'
            /*'1','l','0','O','o','#','@','$','%','&','(',')','|','/','*'//暂时不用特殊字符(包括：数字1,0；字母：l,o,O)
            ,'^','!','~','\\'*/
            };
    static Random random = new Random();

    /**
     * 产生n[4,4+]个随机数
     * @param n
     * @return
     */
    static String getRandomString(int n){
        StringBuffer buffer = new StringBuffer();
        if (n < 4) {
            n = 4;
        }
        for (int i = 0; i < n; i++) {
            buffer.append(dictionary[random.nextInt(dictionary.length)]);
        }
        return buffer.toString();
    }

    /**
     * 随机颜色
     * @return
     */
    static Color getRandomColor(){
        return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
    }

    /**
     * 颜色反色
     * @param c
     * @return
     */
    static Color getReverseColor(Color c){
        return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue());
    }

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

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("image/jpeg");

        String randomString = getRandomString(6);

        request.getSession(true).setAttribute("code", randomString);

        int width = 100; //验证码图片宽度
        int height = 30; //验证码图片高度

        Color color = getRandomColor();

        Color reverse = getReverseColor(color);

        //创建一个彩图
        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //绘图对象
        Graphics2D g = bi.createGraphics();

        g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16));
        g.setColor(color);
        g.fillRect(0, 0, width, height);
        g.setColor(reverse);
        g.drawString(randomString, 18, 20);

        //绘制最多100个噪音点
        for (int i = 0, n = random.nextInt(100); i < n; i++) {
            g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
        }

        ServletOutputStream out = response.getOutputStream();

        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

        encoder.encode(bi);

        out.flush();

        out.close();
    }

}