验证码：http://china.alibaba.com/member/showimage

Question

需要类似标题的验证码。技术要点：彩色、燥点、倾斜。望不吝赐教！

Answer 1

package com.demo.common;import java.awt.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;import javax.imageio.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class CheckImage
    extends HttpServlet
{
    private static final String CONTENT_TYPE = "text/html; charset=UTF-8";    //Initialize global variables
    public void init()
        throws ServletException
    {
    }    //Process the HTTP Get request
    /** Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     * @exception ServletException
     * @throws IOException ServletException
     */
    protected void doGet(HttpServletRequest request,
                         HttpServletResponse response)
        throws ServletException, IOException
    {
        processRequest(request, response);
    }
    //Process the HTTP Post request
    /** Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     * @exception ServletException
     * @exception IOException
     * @throws IOException ServletException
     */
    protected void doPost(HttpServletRequest request,
                          HttpServletResponse response)
        throws ServletException, IOException
    {
        processRequest(request, response);
    }    /** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     * @exception IOException
     * @exception ServletException
     */
    protected void processRequest(HttpServletRequest request,
                                  HttpServletResponse response)
        throws ServletException, IOException
    {
        response.setContentType("image/jpeg");
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        HttpSession session = request.getSession();
        // 在内存中创建图象
        int width = 60, height = 20;
        BufferedImage image = new BufferedImage(width, height,
                                                BufferedImage.TYPE_INT_RGB);        // 获取图形上下文
        Graphics g = image.getGraphics();        //生成随机类
        Random random = new Random();        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);        //设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));        //画边框
        //g.setColor(new Color());
        //g.drawRect(0,0,width-1,height-1);
        // 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 = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }        // 取随机产生的认证码(4位数字)
        int tRand = 1000 + random.nextInt(8999);
        String sRand = ""+tRand;
        for (int i = 0; i < 4; i++)
        {
            String rand = String.valueOf(random.nextInt(10));
//            sRand += rand;
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110),
                                 20 + random.nextInt(110),
                                 20 + random.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(String.valueOf(sRand.charAt(i)), 13 * i + 6, 16);
        }        // 将认证码存入SESSION
        session.setAttribute("rand", sRand);
        // 图象生效
        g.dispose();
        ServletOutputStream responseOutputStream = response.getOutputStream();
        // 输出图象到页面
        ImageIO.write(image, "JPEG", responseOutputStream);        //以下关闭输入流！
        responseOutputStream.flush();
        responseOutputStream.close();
    }    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 (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);
    }    //Clean up resources
    public void destroy()
    {
    }    /** Returns a short description of the servlet.
     * @return ""
     */
    public String getServletInfo()
    {
        return "Short description";
    }
    // </editor-fold>}
web.xml中部署该serlvet  <servlet>
    <servlet-name>checkImage</servlet-name>
    <servlet-class>com.demo.common.CheckImage</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>checkImage</servlet-name>
    <url-pattern>/checkImage</url-pattern>
  </servlet-mapping>jsp页面中使用 <img alt=验证码 src="/ckeckImage" />

Answer 2

http://china.alibaba.com/member/showimage 人家这个就挺好！，又清楚又倾斜，彩色、燥点。有没有知道怎么做倾斜的？