package checking;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.BufferedReader;import java.io.FileReader;import java.io.IOException;import java.util.ArrayList;import java.util.List;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;/** * 验证码生成程序 */public class CheckImgServlet extends HttpServlet {    // 集合中保存所有成语    private List
     
       words = new ArrayList
      
       ();    @Override    public void init() throws ServletException {        // 初始化阶段，读取new_words.txt        // web工程中读取文件，必须使用绝对磁盘路径        String path = getServletContext().getRealPath("/WEB-INF/new_words.txt");        try {            BufferedReader reader = new BufferedReader(new FileReader(path));            String line;            while ((line = reader.readLine()) != null) {                words.add(line);            }            reader.close();        } catch (IOException e) {            e.printStackTrace();        }    }    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // 禁止缓存        // response.setHeader("Cache-Control", "no-cache");        // response.setHeader("Pragma", "no-cache");        // response.setDateHeader("Expires", -1);        int width = 120;        int height = 30;        // 步骤一 绘制一张内存中图片        BufferedImage bufferedImage = new BufferedImage(width, height,                BufferedImage.TYPE_INT_RGB);        // 步骤二 图片绘制背景颜色 ---通过绘图对象        Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔        // 绘制任何图形之前 都必须指定一个颜色        graphics.setColor(getRandColor(200, 250));        graphics.fillRect(0, 0, width, height);        // 步骤三 绘制边框        graphics.setColor(Color.WHITE);        graphics.drawRect(0, 0, width - 1, height - 1);        // 步骤四 四个随机数字        Graphics2D graphics2d = (Graphics2D) graphics;        // 设置输出字体        graphics2d.setFont(new Font("宋体", Font.BOLD, 18));        Random random = new Random();// 生成随机数        int index = random.nextInt(words.size());        String word = words.get(index);// 获得成语        // 定义x坐标        int x = 10;        for (int i = 0; i < word.length(); i++) {            // 随机颜色            graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random                    .nextInt(110), 20 + random.nextInt(110)));            // 旋转 -30 --- 30度            int jiaodu = random.nextInt(60) - 30;            // 换算弧度            double theta = jiaodu * Math.PI / 180;            // 获得字母数字            char c = word.charAt(i);            // 将c 输出到图片            graphics2d.rotate(theta, x, 20);            graphics2d.drawString(String.valueOf(c), x, 20);            graphics2d.rotate(-theta, x, 20);            x += 30;        }        // 将验证码内容保存session        request.getSession().setAttribute("checkcode_session", word);        // 步骤五 绘制干扰线        graphics.setColor(getRandColor(160, 200));        int x1;        int x2;        int y1;        int y2;        for (int i = 0; i < 30; i++) {            x1 = random.nextInt(width);            x2 = random.nextInt(12);            y1 = random.nextInt(height);            y2 = random.nextInt(12);            graphics.drawLine(x1, y1, x1 + x2, x2 + y2);        }        // 将上面图片输出到浏览器 ImageIO        graphics.dispose();// 释放资源                //将图片写到response.getOutputStream()中        ImageIO.write(bufferedImage, "jpg", response.getOutputStream());    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }    /**     * 取其某一范围的color     *      * @param fc     *            int 范围参数1     * @param bc     *            int 范围参数2     * @return Color     */    private Color getRandColor(int fc, int bc) {        // 取其随机颜色        Random random = new Random();        if (fc > 255) {            fc = 255;        }        if (bc > 255) {            bc = 255;        }        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);    }}