随机验证码

随机验证码程序

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.servlet.Servlet;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

* @version 1.0

* @author baiyf

public class ValidateImg extends HttpServlet implements Servlet {

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);

}

/**

* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

public void doGet(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

doPost(req, resp);

}

/**

* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

public void doPost(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

resp.setHeader( " Pragma " , " No-cache " );

resp.setHeader( " Cache-Control " , " no-cache " );

resp.setDateHeader( " Expires " , 0 );

// 在内存中创建图象

int width = 90 , height = 40 ;

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 获取图形上下文

Graphics g = image.createGraphics();

// 设定背景色

g.setColor(getRandColor( 180 , 250 ));

g.fillRect( 0 , 0 , width, height);

Random random = new Random();

// 生成干扰椭圆

for ( int i = 0 ; i < 5 ; i ++ ) {

g.setColor(getRandColor( 50 , 100 ));

int x = random.nextInt(width);

int y = random.nextInt(height);

g.drawOval(x, y, 4 , 4 );

}

g.setFont( new Font( "" , Font.PLAIN, 40 ));

String sRand = "" ;

for ( int i = 0 ; i < 4 ; i ++ ) {

// 取随机产生的认证码(4位数字)

String rand = String.valueOf(random.nextInt( 10 ));

sRand += rand;

// 随机产生颜色

g.setColor(

new Color(

20 + random.nextInt( 80 ),

20 + random.nextInt( 100 ),

20 + random.nextInt( 90 )));

// 画数字

g.drawString(rand, ( 17 + random.nextInt( 3 )) * i + 8 , 34 );

// 生成干扰线

for ( int k = 0 ; k < 12 ; k ++ ) {

int x = random.nextInt(width);

int y = random.nextInt(height);

int xl = random.nextInt( 9 );

int yl = random.nextInt( 9 );

g.drawLine(x, y, x + xl, y + yl);

}

req.getSession().setAttribute( " rand " ,sRand);

g.dispose();

javax.imageio.ImageIO.write(image, " JPEG " , resp.getOutputStream());

}

posted on 2006-06-26 22:02 baim 阅读(222) 评论(0) 编辑收藏

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