java验证码生成

第一种方式：纯代码

先写jsp:

在编写CaptServlet:

 package cn.itcast.web.controller;

 import java.awt.Color;
 import java.awt.Font;
 import java.awt.Graphics;
 import java.awt.image.BufferedImage;
 /**
  * 用户登陆
  */
 import java.io.IOException;
 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;

 public class CaptServlet extends HttpServlet {
     private static final long serialVersionUID = 1L;

     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         int width = 120;
         int height = 25;
         //验证码
         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
         //画笔
         Graphics g = image.getGraphics();
             //设置颜色,设置一个边线
             g.setColor(Color.green);
             g.drawRect(0, 0, width, height);
             //设置填充色
             g.setColor(Color.yellow);
             g.fillRect(1, 1, width-2, height-2);
             //干扰线
             g.setColor(Color.gray);
             Random r = new Random();
             g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height));
             //随机验证码
             g.setColor(Color.black);
             g.setFont(new Font("宋体", Font.BOLD|Font.ITALIC, 20));
             int x = 20;
             for(int i=0;i<4;i++) {
             String num = r.nextInt(10)+"";
             g.drawString(num, x, 20);
             x+=20;
             }
         //输出到页面
             ImageIO.write(image, "jpg", response.getOutputStream());
     }

---

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

 }

页面效果：

//**********************推荐（validatecode 的jar包网上能搜到）

两行轻松搞定。**********************************************************************************************