java之使用Servlet生成验证码的源码分享

import java.awt.Color;
import java.awt.Font;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;


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

import org.apache.commons.lang.math.RandomUtils;

import nl.captcha.Captcha;
import nl.captcha.Captcha.Builder;
import nl.captcha.gimpy.BlockGimpyRenderer;
import nl.captcha.text.producer.ChineseTextProducer;
import nl.captcha.text.producer.DefaultTextProducer;
import nl.captcha.text.renderer.DefaultWordRenderer;
import nl.captcha.text.renderer.WordRenderer;

public class CaptchaServlet extends HttpServlet implements Servlet {
    private static final long serialVersionUID = 1L;
    private static final String PARAM_HEIGHT = "height"; // 高度 默认为50


    private static final String PARAM_WIDTH = "width";// 宽度 默认为200

    private static final String PAEAM_NOISE = "noise";// 干扰线条 默认是没有干扰线条

    private static final String PAEAM_TEXT = "text";// 文本

    protected int _width = 150;
    protected int _height = 40;
    protected boolean _noise = false;
    protected String _text = "number:1,word:1,number:1,number:1,word:1";

    /**
     * 初始化过滤器.将配置文件的参数文件赋值
     *
     * @throws ServletException
     */
    @Override
    public void init() throws ServletException {
        if (getInitParameter(PARAM_HEIGHT) != null) {
            _height = Integer.valueOf(getInitParameter(PARAM_HEIGHT));
        }

        if (getInitParameter(PARAM_WIDTH) != null) {
            _width = Integer.valueOf(getInitParameter(PARAM_WIDTH));
        }

        if (getInitParameter(PAEAM_NOISE) != null) {
            _noise = Boolean.valueOf(getInitParameter(PAEAM_NOISE));
        }

        if (getInitParameter(PAEAM_NOISE) != null) {
            _text = String.valueOf(getInitParameter(PAEAM_TEXT));
        }
    }

    /**
     * 因为获取图片只会有get方法
     */
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        Builder builder = new Captcha.Builder(_width, _height);
        // 增加边框
        // builder.addBorder();
        // 是否增加干扰线条
        if (_noise == true) {
            builder.addNoise();
        }
        // ----------------自定义字体大小-----------
        // 自定义设置字体颜色和大小 最简单的效果 多种字体随机显示
        List<Font> fontList = new ArrayList<Font>();
        fontList.add(new Font("微软 雅黑", Font.LAYOUT_NO_START_CONTEXT, 30));// 可以设置斜体之类的
        DefaultWordRenderer dwr = new DefaultWordRenderer(getRandomColor(), fontList);
        // 加入多种颜色后会随机显示 字体空心

        WordRenderer wr = dwr;
        // 增加文本，默认为5个随机字符.
        if (_text == null) {
            builder.addText();
        } else {
            String[] ts = _text.split(",");
            for (int i = 0; i < ts.length; i++) {
                String[] ts1 = ts[i].split(":");
                if ("chinese".equals(ts1[0])) {
                    builder.addText(new ChineseTextProducer(Integer.parseInt(ts1[1])), wr);
                } else if ("number".equals(ts1[0])) {
                    // 这里没有0和1是为了避免歧义 和字母I和O
                    char[] numberChar = new char[]{'2', '3', '4', '5', '6', '7', '8'};
                    builder.addText(new DefaultTextProducer(Integer.parseInt(ts1[1]), numberChar), wr);
                } else if ("word".equals(ts1[0])) {
                    // 原理同上
                    char[] numberChar = new char[]{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'k', 'm', 'n', 'p', 'r',
                            'w', 'x', 'y'};
                    builder.addText(new DefaultTextProducer(Integer.parseInt(ts1[1]), numberChar), wr);
                } else {
                    builder.addText(new DefaultTextProducer(Integer.parseInt(ts1[1])), wr);
                }
            }

        }

        // --------------添加背景-------------
        // 设置背景渐进效果 以及颜色 form为开始颜色，to为结束颜色
        // GradiatedBackgroundProducer gbp=new GradiatedBackgroundProducer();
        // gbp.setFromColor(Color.yellow);
        // gbp.setToColor(Color.red);
        // 无渐进效果，只是填充背景颜色
        // FlatColorBackgroundProducer fbp=new
        // FlatColorBackgroundProducer(Color.red);
        // 加入网纹--一般不会用
        // SquigglesBackgroundProducer sbp=new SquigglesBackgroundProducer();
        // 没发现有什么用,可能就是默认的
        // TransparentBackgroundProducer tbp = new
        // TransparentBackgroundProducer();

        // builder.addBackground(gbp);
        // ---------装饰字体---------------
        // 字体边框齿轮效果 默认是3
        builder.gimp(new BlockGimpyRenderer(1));
        // 波纹渲染 相当于加粗
        // builder.gimp(new RippleGimpyRenderer());
        // 修剪--一般不会用
        // builder.gimp(new ShearGimpyRenderer(Color.red));
        // 加网--第一个参数是横线颜色，第二个参数是竖线颜色
        // builder.gimp(new FishEyeGimpyRenderer(Color.red,Color.yellow));
        // 加入阴影效果 默认3，75
        // builder.gimp(new DropShadowGimpyRenderer());
        // 创建对象
        Captcha captcha = builder.build();

        req.getSession().setAttribute("simpleCaptcha", captcha);
        resp.setHeader("Cache-Control", "private,no-cache,no-store");
        resp.setContentType("image/png");
        try {
            OutputStream os = resp.getOutputStream();
            ImageIO.write(captcha.getImage(), "png", os);
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public Color getRandomColor() {
        int n = RandomUtils.nextInt(100);

        if (n % 3 == 1) {
            return Color.RED;
        } else if (n % 3 == 2) {
            return Color.BLUE;
        }
        return Color.GREEN;
    }
}