package com.gys;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.Httpsession;public class MakeCode {    PRivate Random random = new Random();    private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//隨機產生的字符串        private int width = 80;//圖片寬    private int height = 26;//圖片高    private int lineSize = 40;//干擾線數量    private int stringNum = 4;//隨機產生字符數量    /*     * 獲得字體     */    private Font getFont(){        return new Font("Fixedsys",Font.CENTER_BASELINE,18);    }    /*     * 獲得顏色     */    private Color getRandColor(int fc,int bc){        if(fc > 255)            fc = 255;        if(bc > 255)            bc = 255;        int r = fc + random.nextInt(bc-fc-16);        int g = fc + random.nextInt(bc-fc-14);        int b = fc + random.nextInt(bc-fc-18);        return new Color(r,g,b);    }    /**     * 生成隨機圖片     */    public void getRandcode(HttpServletRequest request,            HttpServletResponse response) {        HttpSession session = request.getSession();        //BufferedImage類是具有緩沖區的Image類,Image類是用于描述圖像信息的類        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);        Graphics g = image.getGraphics();//產生Image對象的Graphics對象,該對象可以在圖像上進行各種繪制操作        g.fillRect(0, 0, width, height);        g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));        g.setColor(getRandColor(110, 133));        //繪制干擾線        for(int i=0;i<=lineSize;i++){            drowLine(g);        }        //繪制隨機字符        String randomString = "";        for(int i=1;i<=stringNum;i++){            randomString=drowString(g,randomString,i);        }        session.removeAttribute("code");        session.setAttribute("code", randomString);        System.out.println(randomString);        g.dispose();        try {            ImageIO.write(image, "JPEG", response.getOutputStream());//將內存中的圖片通過流動形式輸出到客戶端        } catch (Exception e) {            e.printStackTrace();        }    }    /*     * 繪制字符串     */    private String drowString(Graphics g,String randomString,int i){        g.setFont(getFont());        g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));        String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));        randomString +=rand;        g.translate(random.nextInt(3), random.nextInt(3));        g.drawString(rand, 13*i, 16);        return randomString;    }    /*     * 繪制干擾線     */    private void drowLine(Graphics g){        int x = random.nextInt(width);        int y = random.nextInt(height);        int xl = random.nextInt(13);        int yl = random.nextInt(15);        g.drawLine(x, y, x+xl, y+yl);    }    /*     * 獲取隨機的字符     */    public String getRandomString(int num){        return String.valueOf(randString.charAt(num));    }}

package com.gys;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class GetCodeServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("image/jpeg");//設置相應類型,告訴瀏覽器輸出的內容為圖片        response.setHeader("Pragma", "No-cache");//設置響應頭信息，告訴瀏覽器不要緩存此內容        response.setHeader("Cache-Control", "no-cache");        response.setDateHeader("Expire", 0);        MakeCode makeCode = new MakeCode();        try {            makeCode.getRandcode(request, response);//輸出圖片方法        } catch (Exception e) {            e.printStackTrace();        }    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee                                                    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">    <servlet>        <servlet-name>GetCodeServlet</servlet-name>        <servlet-class>com.gys.GetCodeServlet</servlet-class>    </servlet>    <servlet-mapping>        <servlet-name>GetCodeServlet</servlet-name>        <url-pattern>/getCode</url-pattern>    </servlet-mapping>        <welcome-file-list>        <welcome-file>index.jsp</welcome-file>    </welcome-file-list></web-app>

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>驗證碼</title>     <script type="text/Javascript">        function getCode(obj) {            obj.src = "getCode?"+Math.random();//防止出現緩存        }    </script>  </head>    <body>        <img title="點擊更換" onclick="getCode(this);" src="getCode"><br/>  </body></html>