validateutil.java

一个由jsp+servlet+MySQL简单的新闻发布系统

package com.news.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;
/*
 * 显示验证码功能
 */
public class ValidateUtil {
	
	private String sRand = "";

    public BufferedImage creatImage(){
        // 在内存中创建图象
        int width = 48, height = 18;
        int fontSize = 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(new Color(186, 227, 244));
        g.fillRect(0, 0, width, height);

        // 设定字体
        g.setFont(new Font("Times New Roman", Font.BOLD, fontSize));

        // 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(180, 250));
        for(int i = 0; i < 50; i++){
            int x = random.nextInt(width - 5);
            int y = random.nextInt(height - 5);
            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 rand = request.getParameter("rand");
        // rand = rand.substring(0,rand.indexOf("."));

        int fontNum = 4;
        int w0 = 4;
        int fontw = (width - (fontNum + 1) * w0) / fontNum;
        for(int i = 0; i < fontNum; i++){
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            // 将认证码显示到图象中
            g.setColor(new Color(random.nextInt(10), random.nextInt(20), random.nextInt(30)));
            g.drawString(rand, w0 + (fontw + w0) * i, height - 2);
        }
        // 图象生效
        g.dispose();
        return image;
    }

    private 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 n = bc - fc;
        int r = fc + random.nextInt(n);
        int g = fc + random.nextInt(n);
        int b = fc + random.nextInt(n);
        return new Color(r, g, b);
    }

    public String getSRand()
    {
        return sRand;
    }


}