JSP 图片验证码

/*1.定义图片类*/

package servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletResponse;

public class RandImgCreater {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

    }
    //图片上的字符
    private static final String CODE_LIST = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";

    private HttpServletResponse response = null;

    private static final int HEIGHT = 20;//图片高度

    private static final int FONT_NUM = 4;//图片上字符个数

    private int width = 0;//图片宽度

    private int iNum = 0;//图片上字符个数

    private String codeList = "";//图片上的字符

    private boolean drawBgFlag = false;

    private int rBg = 0;//背景色

    private int gBg = 0;//背景色

    private int bBg = 0;//背景色

    /**
     *
     * @param response
     */
    public RandImgCreater(HttpServletResponse response) {

        this.response = response;

        this.width = 13 * FONT_NUM + 12;

        this.iNum = FONT_NUM;

        this.codeList = CODE_LIST;

    }
    /**
     *
     * @param response
     * @param iNum 图片上字符个数
     * @param codeList 图片上的字符
     */
    public RandImgCreater(HttpServletResponse response, int iNum, String codeList) {

        this.response = response;

        this.width = 13 * iNum + 12;

        this.iNum = iNum;

        this.codeList = codeList;

    }
    /**
     * 生成图片
     * @return  图片上的字符
     */
    public String createRandImage() {

        BufferedImage image = new BufferedImage(width, HEIGHT,BufferedImage.TYPE_INT_RGB);

        Graphics g = image.getGraphics();

        Random random = new Random();
       
        //自定义图片背景颜色
        if (drawBgFlag) {

            g.setColor(new Color(rBg, gBg, bBg));

            g.fillRect(0, 0, width, HEIGHT);

        } else {//随机生成图片背景颜色

            g.setColor(getRandColor(200, 250));

            g.fillRect(0, 0, width, HEIGHT);

            for (int i = 0; i < 155; i++) {
                g.setColor(getRandColor(140, 200));
                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);
            }
        }
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
       
        String sRand = "";//随机生成的字符串
        for (int i = 0; i < iNum; i++) {
           
            int rand = random.nextInt(codeList.length());
           
            String strRand = codeList.substring(rand, rand + 1);
           
            sRand += strRand;
           
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));

            g.drawString(strRand, 13 * i + 6, 16);

        }

        g.dispose();

        try {

            ImageIO.write(image, "JPEG", response.getOutputStream());

        } catch (IOException e) {
           e.printStackTrace();
        }

        return sRand;

    }
    /**
     * 设置背景颜色
     * @param r
     * @param g
     * @param b
     */
    public void setBgColor(int r, int g, int b) {
        drawBgFlag = true;
        this.rBg = r;
        this.gBg = g;
        this.bBg = b;
    }

    /**
     * 随机生成颜色
     * @param fc
     * @param bc
     * @return
     */
    private Color getRandColor(int fc, int bc) {
        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);
    }

}

 

/*2.配置在servlet中*/

package servlet;

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class ImageServlet1
 */
public class ImageServlet1 extends HttpServlet {
    private static final long serialVersionUID = 1L;
      
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ImageServlet1() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Servlet#init(ServletConfig)
     */
    public void init(ServletConfig config) throws ServletException {
        // TODO Auto-generated method stub
    }

    /**
     * @see Servlet#destroy()
     */
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        System.out.println("===========request==============");
        HttpSession session=request.getSession(true);
        response.setHeader("Pragma","No-cache");

        response.setHeader("Cache-Control", "no-cache");

        response.setDateHeader("Expires", 0);

        RandImgCreater rc = new RandImgCreater(response);

        // RandImgCreater rc = new RandImgCreater(response,8,"abcdef");

        // rc.setBgColor(100,100,100);

        String rand = rc.createRandImage();

        session.setAttribute("rand", rand);
       
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request,response);
    }

   
   
}

/*3.jsp界面应用*/

 

<%@ page language="java" contentType="text/html; charset=gbk"
    pageEncoding="gbk"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk">
<title>Insert title here</title>
<script type="text/javascript" src="/js/jquery.js"></script>
</head>
<body>
<%
 String code=request.getParameter("code");
 if(session.getAttribute("rand")!=null&&((String)session.getAttribute("rand")).equalsIgnoreCase(code)){     
     out.println("<span style=\"color:#FF0000\"> 验证成功！</span>");
 }
%>
<form name="frm" method="post" action="./myrandTest.jsp">
Hello Image Test<br/>
checkCode:<img id="img_check" src="http://localhost:8080/mailreader/ImageServlet1" >
<a href="#" onclick="getpic();">看不清换张图片</a>
<br />
please input the checkCode:<input type="text" name="code" value=""><br />
<input type="submit" name="btn1" value="check"></form>
</body>
<script type="text/javascript">
 
  function getpic(){
     var requesturl="http://localhost:8080/mailreader/ImageServlet1?d="+new Date();                
     document.getElementById("img_check").src=requesturl;
     //alert(document.getElementById("img_check").src);    
     return false;  
   }
 

</script>
</html>