注册界面图形验证码，防攻击（网站、短信）

/**
	 * 注册界面验证码
	 * 
	 * @param response
	 *            [参数说明]
	 * @return void
	 * @exception throws [违例类型] [违例说明]
	 */
	@RequestMapping("/validatorCode")
	@ResponseBody
	public void validatorCode(HttpServletResponse response) {
		HttpServletRequest request = this.getRequest();
		response.setContentType("image/jpeg");// 设置相应类型,告诉浏览器输出的内容为图片
		response.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expire", 0);
		RandomValidateCode randomValidateCode = new RandomValidateCode();
		try {
			randomValidateCode.getRandcode(request, response);// 输出图片方法
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

/*
 * 文 件 名  :  RandomValidateCode.java
 * 描    述    :  <描述>
 * 创建人    :  
 * 创建时间:   下午4:09:36
 */
package com.umrtec.web.utils.tools;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * <一句话功能简述>
 * <功能详细描述>
 * @author  
 * @version  [版本号, 2013-8-28 下午4:09:36]
 */
public class RandomValidateCode {
	
	public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
    private Random random = new Random();
    private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串
    
    private int width = 90;//图片宽
    private int height = 38;//图片高  
    private int lineSize = 40;//干扰线数量
    private int stringNum = 4;//随机产生字符数量
    /*
     * 获得字体
     */
    private Font getFont(){
        return new Font("Fixedsys",Font.CENTER_BASELINE,26);
    }
    /*
     * 获得颜色
     */
    private Color getRandColor(int fc,int bc){
        if(fc > 255)
            fc = 255;
        if(bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc-fc-16);
        int g = fc + random.nextInt(bc-fc-14);
        int b = fc + random.nextInt(bc-fc-18);
        return new Color(r,g,b);
    }
    /**
     * 生成随机图片
     */
    public void getRandcode(HttpServletRequest request , HttpServletResponse response) {
        HttpSession session = request.getSession();
        //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
        Graphics g = image.getGraphics();//产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
        g.fillRect(0 , 0 , width, height);
        g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,23));
        g.setColor(getRandColor(110, 133));
        //绘制干扰线
        for(int i=0;i<=lineSize;i++){
            drowLine(g);
        }
        //绘制随机字符
        String randomString = "";
        for(int i=1;i<=stringNum;i++){
            randomString=drowString(g,randomString,i);
        }
        session.removeAttribute(RANDOMCODEKEY);
        session.setAttribute(RANDOMCODEKEY, randomString);
        g.dispose();
        try {
            ImageIO.write(image, "JPEG", response.getOutputStream());//将内存中的图片通过流动形式输出到客户端
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /*
     * 绘制字符串
     */
    private String drowString(Graphics g,String randomString,int i){
        g.setFont(getFont());
        g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
        String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
        randomString +=rand;
        g.translate(random.nextInt(3), random.nextInt(3));
        g.drawString(rand, 16*i, 23);
        return randomString;
    }
    /*
     * 绘制干扰线
     */
    private void drowLine(Graphics g){
        int x = random.nextInt(width);
        int y = random.nextInt(height);
        int xl = random.nextInt(13);
        int yl = random.nextInt(15);
        g.drawLine(x, y, x+xl, y+yl);
    }
    /*
     * 获取随机的字符
     */
    public String getRandomString(int num){
        return String.valueOf(randString.charAt(num));
    }
}