<IMG id=geneValidCode alt=验证码 src="random.shtml" align=absMiddle border=0>

package com.game.web.action;


import java.io.ByteArrayInputStream;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;

import com.game.web.util.RandomNumUtil;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;


public class RandomAction extends ActionSupport {
    
    private static final long serialVersionUID = 1L;

    private ByteArrayInputStream inputStream;

    public String execute() throws Exception {

        HttpServletResponse response = ServletActionContext.getResponse();

        response.setHeader("Pragma","No-cache"); 
        
        response.setHeader("Cache-Control","no-cache");
        
        response.setHeader("Cache-Control", "no-store");
        
        response.setDateHeader("Expires", 0); 

        RandomNumUtil rdnu=RandomNumUtil.Instance();    
        
        this.setInputStream(rdnu.getImage());  
        
        ActionContext.getContext().getSession().put("random", rdnu.getString());    

        return SUCCESS;    
    }


    public void setInputStream(ByteArrayInputStream inputStream) {
        this.inputStream = inputStream;
    }

    public ByteArrayInputStream getInputStream() {
        return inputStream;
    }

}


package com.game.web.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;

/**
* Project:
* Filename: RandomNumUtil.java
* Company: 
* Copyright: 
* Description: 验证码生成器
* Date 
*/
public class RandomNumUtil {
    private ByteArrayInputStream image;// 图像

    private String str;// 验证码

    private RandomNumUtil() {
        init();// 初始化属性
    }

    /*
     * 取得RandomNumUtil实例
     */
    public static RandomNumUtil Instance() {

        return new RandomNumUtil();
    }

    /*
     * 取得验证码图片
     */
    public ByteArrayInputStream getImage() {
        return this.image;
    }

    /*
     * 取得图片的验证码
     */
    public String getString() {
        return this.str;
    }

    private void init() {
        // 在内存中创建图象
        int width = 52, height = 20;
        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));
        // 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);
        }