validatecode.java

用struts

package com.accp.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.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ValidateCode extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public ValidateCode() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
//		设置页面不缓存
		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=18;
		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));

//		画边框
//		g.setColor(new Color());
//		g.drawRect(0,0,width-1,height-1);

//		 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
		request.getSession().setAttribute("rand",sRand);

//		 图象生效
		g.dispose();

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


	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request,response);
	}

	public Color getRandColor(int fc,int bc){
		//给定范围获得随机颜色
        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);
    }
	
	public void init() throws ServletException {
		// Put your code here
	}

}