java 验证码生成

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;
}

}</pre>