randomcodeservlet.java

用jsp,servlet实现人力资源管理系统

package com.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;

import javax.servlet.*;
import javax.servlet.http.*;

public class RandomCodeServlet extends HttpServlet{
	//验证码图片的宽度 
	private int width = 60;
	//验证码图片的高度
	private int height = 20;
	
	protected void service(HttpServletRequest req,HttpServletResponse resp)
		throws ServletException,java.io.IOException
	{
		BufferedImage buffImg = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
		Graphics2D g = buffImg.createGraphics();
		
		//创建一个随即数生成器
		Random random = new Random();
		
		g.fillRect(0, 0, width, height);
		
		//创建字体,字体的大小应该根据图片的高度来决定
		Font font = new Font("Times New Roman",Font.PLAIN,18);
		
		//设置字体
		g.setFont(font);
		
		//画边框
		g.setColor(Color.BLACK);
		g.drawRect(0, 0, width-1, height-1);
		
		//随即产生60条干扰线,使图像中的认证码不易被其他的程序探测到
		g.setColor(Color.GRAY);
		for(int i = 0;i<60;i++){
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int x1 = random.nextInt(12);
			int y1 = random.nextInt(12);
			g.drawLine(x, y, x+x1, y+y1);
		}
		
		//randomCode用于保存随即产生的验证码,以便于用户登录后进行验证
		StringBuffer randomCode = new StringBuffer();
		int red = 0,green = 0,blue = 0;
		
		//随机产生4位数字的验证码
		for(int i = 0;i < 4;i++){
			//得到随机产生的验证码
			String strRand = String.valueOf(random.nextInt(10));
			
			//产生随机的颜色分量来构造颜色值,这样输出的每位数字的颜色值都将不同
			red = random.nextInt(110);
			green = random.nextInt(50);
			blue = random.nextInt(50);
			
			//用随机产生的颜色将验证码绘制到图像中 
			g.setColor(new Color(red,green,blue));
			g.drawString(strRand, 13*i+6, 16);
			
			//将产生的四个随机数组合在一起
			randomCode.append(strRand);
		}
		//将四位数字的验着码保存到Session中
		 HttpSession session = req.getSession();
		 session.setAttribute("randomCode", randomCode.toString());
		 
		 //禁止图像缓存
		 resp.setHeader("Pragma", "no-cache");
		 resp.setHeader("Cache-Control", "no-cache");
		 resp.setDateHeader("Expires", 0);
		 
		 resp.setContentType("image/jpeg");
		 //将图像输出到Servlet输出流中
		 ServletOutputStream sos = resp.getOutputStream();
		 ImageIO.write(buffImg, "jpeg", sos);
		 sos.close();
	}
}