登录获取随机码

login.jsp:

      <td height="37"><span class="validate">
        <input type="text" name="admin.rand" id="randText"  maxlength="4"/>
      </span><span class="img1"><img src="rand.action"  onclick="changeValidateCode(this)" title="点击图片刷新验证码" id="randNum"/></span>
      </td>

function changeValidateCode(obj) {    
//获取当前的时间作为参数    
var timenow = new Date().getTime();    
//每次请求需要一个不同的参数，否则可能会返回同样的验证码       
obj.src="rand.action?d="+timenow;    
}  

struts/adminmanage.xml:

        <!-- Random验证码 -->   
        <action name="rand" class="randomAction" method="rand">      
           <result type="stream">      
                <param name="contentType">image/jpeg</param>      
                <param name="inputName">inputStream</param>      
           </result>   
       </action>

RandomAction.JAVA:
import java.io.ByteArrayInputStream;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Controller;

import com.XXX.dhm.iepgm.base.web.action.BaseAction;
import com.XXX.dhm.iepgm.common.util.RandomNumUtil;
import com.opensymphony.xwork2.ActionContext;

/**
 *
 * 产生随机数，用于用户登录页面的校验码生成。
 */
@Scope("prototype")
@Controller
public class RandomAction extends BaseAction
{

    private static final long serialVersionUID = 1L;

    /** 字节流，用于生成图片 */
    private transient ByteArrayInputStream inputStream;

    /**
     * 生成登录页面验证码图片
     * @return String
     * @throws 抛出IEPGMException类型的异常
     *         ，该异常是Exception的子类，用于封装错误代码和数据库异常信息，用于拦截器捕获并处理该异常。
     */
    public String rand() throws Exception
    {

        RandomNumUtil rdnu = RandomNumUtil.instance();
        // 取得带有随机字符串的图片
        this.setInputStream(rdnu.getImage());
        // 取得随机字符串放入HttpSession
        ActionContext.getContext().getSession().put("random", rdnu.getString());

        return SUCCESS;
    }

    public ByteArrayInputStream getInputStream()
    {
        return inputStream;
    }

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

RandomNumUtil.JAVA:
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;

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 = 60, 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)
        StringBuffer sRand = new StringBuffer();
        for (int i = 0; i < 4; i++)
        {
            String rand = String.valueOf(random.nextInt(10));
            sRand.append(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);
        }
        // 赋值验证码
        this.str = sRand.toString();

        // 图象生效
        g.dispose();
        ByteArrayInputStream input = null;
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        try
        {
            ImageOutputStream imageOut = ImageIO
                    .createImageOutputStream(output);
            ImageIO.write(image, "JPEG", imageOut);
            imageOut.close();
            input = new ByteArrayInputStream(output.toByteArray());
        }
        catch (Exception e)
        {
            System.out.println("验证码图片产生出现错误：" + e.toString());
        }

        this.image = input;/* 赋值图像 */
    }

    /*
     * 给定范围获得随机颜色
     */
    private 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);
    }

}