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。**********************************************************************************************