struts2 实现随机验证码

action中的代码：

@Controller(value = "randomPictureAction")
public class RandomPictureAction extends BaseAction {

	private static final long serialVersionUID = -6950908478971552308L;   
	private ByteArrayInputStream inputStream;   
	  
	public String execute() throws Exception {
		
      // 在内存中创建图象   
       int width = 85, 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(6位数字)   
        String sRand = "";   
        for (int i = 0; i < 6; 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);   
        }   
	  
        // 将认证码存入SESSION   
        ActionContext.getContext().getSession().put("rand", sRand);
        //this.getRequest().setAttribute("rand", sRand);
        this.str = sRand;
        System.out.println("rand="+sRand);
        // 图象生效   
        g.dispose();   
        ByteArrayOutputStream output = new ByteArrayOutputStream();   
        ImageOutputStream imageOut = ImageIO.createImageOutputStream(output);   
        ImageIO.write(image, "JPEG", imageOut);   
        imageOut.close();   
        ByteArrayInputStream input = new ByteArrayInputStream(output   .toByteArray());   
        this.setInputStream(input);   
        return SUCCESS;
	 }   
	  
    /*  
     * 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);   
    }   
	  	
    public void setInputStream(ByteArrayInputStream inputStream) {   
        this.inputStream = inputStream;   
    }   
  
    public ByteArrayInputStream getInputStream() {   
        return inputStream;   
    }
}

xml中的代码实现：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
<!-- Struts2配置文件 -->
<struts>
	<!-- 景阳岗酒业客户留言管理 -->
   	<package name="randpicture" namespace="/" extends="struts-default,json-default">
	<!-- 工具action -->
	<action name="rand" class="randomPictureAction"> 
	    <result name="success" type="stream">
		<param name="contentType">image/jpeg</param>  
		<param name="inputName">inputStream</param>
	    </result>
	</action>
	</package>
</struts>

jsp页面中的代码实现：

<script type="text/javascript"> 
function changeValidateCode(obj) {   
    var currentTime= new Date().getTime();
    obj.src = "rand?d=" + currentTime;
}
</script>

<img src="rand" onclick="changeValidateCode(this)" />