验证码

文件:	验证码.rar
大小:	2767KB
下载:	下载

下面完整的代码:

后台代码:

package demo;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;
import javax.imageio.*;

public class VlidateServlet extends HttpServlet {
    private static final String CONTENT_TYPE = "image/jpeg; charset=GBK";

    //Initialize global variables
    public void init() throws ServletException {
    }

    //Process the HTTP Get request
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        response.setContentType(CONTENT_TYPE);
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);

        // 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));

        // 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)
        String sRand = "";
        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(rand, 13 * i + 6, 16);
        }

        // 将认证码存入SESSION
        HttpSession session = request.getSession(true);
        session.setAttribute("rand", sRand);

        // 图象生效
        g.dispose();

        // 输出图象到页面
        ImageIO.write(image, "JPEG", response.getOutputStream());

    }

    //给定范围获得随机颜色
    public 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);
    }

    //Process the HTTP Post request
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        doGet(request, response);
    }

    //Clean up resources
    public void destroy() {
    }
}

///前台代码:

  < contentType="text/html; charset=GBK"%>
< uri="/WEB-INF/struts-bean.tld" prefix="bean"%>
< uri="/WEB-INF/struts-html.tld" prefix="html"%>
< uri="/WEB-INF/struts-logic.tld" prefix="logic"%>
< uri="/WEB-INF/struts-nested.tld" prefix="nested"%>

 
   
 
 
          用户名:
     
     

      密码:
     
     

      验证码:
     
        ///这里就是验证码的代码精髓所在
     

     
   
 

 

总结:

  在我们使用验证码的时候 一般的想法就是在image标签里面的src给一个图片路径 吧！ 其实 我们给的是servler的映射路径啊！ servlet就是在页面上画了一张验证码的画 把他的路径给image就相当于给了一张画的路径