java验证码的实现（ssi）

总体流程：

    html页面发送生成验证码请求，java服务端生成对应的验证吗并回写到页面，点击验证码或者刷新页面及页面报错情况下，验证码都要刷新。

html端：

 

<img id="imageCode" alt="验证码" src="image_getImgCode.do" 
    style="margin-left:20px;height:36px;cursor: pointer;" />
$(function(){
    //为图片绑定单击事件
    $('#imageCode').click(function(){
       	//设置src属性为action的参数为当前时间，保证验证码点击之后可以变换
       	$(this).attr('src', 'image_getImgCode.do?dt=' + new Date().getTime());
    });
});

struts.xml：

 

 

<action name="image_*" class="imageDemoAction" method="{1}"></action>

spring配置文件：

 

 

<bean id="imageDemoAction" class="com.infohold.businessyun.action.ImageDemoAction" 
    scope="prototype">
</bean>

 action:

public class ImageDemoAction extends ActionSupport{
	private static final long serialVersionUID = 1L;
	private Logger logger = Logger.getLogger(ImageDemoAction.class);
	//stream result只能输出InputStream类型
    private InputStream imageStream;

    public InputStream getImageStream() {
        return imageStream;
    }

    public void setImageStream(InputStream imageStream) {
        this.imageStream = imageStream;
    }
    
    public void getImgCode() throws IOException{
    	HttpServletResponse response = ServletActionContext.getResponse();
    	HttpServletRequest request = ServletActionContext.getRequest();
        //生成验证码
        Map<String, BufferedImage> map = ImageUtil.createImage();
        String key = map.keySet().iterator().next();
        HttpSession session = request.getSession();
        session.removeAttribute("key");
        session.setAttribute("key", key);
        BufferedImage image = map.get(key);
        try{
            imageStream = ImageUtil.getInputStream(image);
            OutputStream outputStream = response.getOutputStream();  
            ImageIO.write(image, "jpeg", outputStream);  
            outputStream.close();
        }catch(IOException e){
        	logger.error("生成验证码失败:"+e.getMessage());
        	e.printStackTrace();
        }
    }
}

 工具类：

/**
 * 简单验证码生成工具
 * ImageUtil, 用于生成验证码
 * createImage方法返回一个Map类型,Map 的key是所生产的验证码的字符串,
 * Map的value是所生产的BufferImage类型的验证码;
 * getInputStream方法将 BufferImage转成InputStream类型;
 * @author jiqing
 */
public class ImageUtil {
    private static final char[] chars = {'0','1','2','3','4','5','6','7','8','9',
        'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q',
        'r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H',
        'I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
    private static final int SIZE = 4;            //字符数
    private static final int LINES = 12;        //干扰线数量
    private static final int WIDTH = 130;        //生成的验证码图片的宽度
    private static final int HEIGHT = 60;        //生成的验证码图片的长度
    private static final int FONT_SIZE = 40;    //字体大小

    public static Map<String, BufferedImage> createImage(){
        //用户保存字符串
        StringBuffer sb = new StringBuffer();
        //BufferImage类型的验证码
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        //获得画笔 
        Graphics g = image.getGraphics();
        g.setColor(Color.LIGHT_GRAY);    //设置背景色
        g.fillRect(0, 0, WIDTH, HEIGHT);//将背景色填充到图片中
        Random ran = new Random();    //获得一个Random对象
        
        //画字符
        for(int i=1; i<=SIZE; i++){
            int r = ran.nextInt(chars.length);    //得到一个随机的下标, chars 是保存着若干字符的char字符
            g.setColor(getRandomColor());        //得到一个随机的颜色
            g.setFont(new Font(null, Font.BOLD+Font.ITALIC, FONT_SIZE));    //设置字体大小
            g.drawString(chars[r]+"", (i-1)*WIDTH/SIZE, (int)(HEIGHT*0.7));    //画字符
            sb.append(chars[r]);
        }
        
        //画干扰线
        for(int i=1; i<=LINES; i++){
            g.setColor(getRandomColor());    //同样，干扰线也是用随机的颜色
            g.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT), 
                    ran.nextInt(WIDTH), ran.nextInt(HEIGHT));//随机设置干扰线的方向
        }
        
        //将图片中的字符串保存为Map对象的key，BufferedImage保存为value
        Map<String, BufferedImage> map = new HashMap<String, BufferedImage>();    
        map.put(sb.toString(), image);
        return map;
    }

    /**
     * 获得一个随机的颜色 返回 Color对象
     * @return
     */
    private static Color getRandomColor() {
        Random ran = new Random();
        Color color = new Color(ran.nextInt(256), ran.nextInt(256), ran.nextInt(256)); 
        return color;
    }

    /**
     * 将 BufferImage转成InputStream类型
     * @param image
     * @return
     * @throws IOException
     */
    public static InputStream getInputStream(BufferedImage image) throws IOException{
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(bos);
        encoder.encode(image);
        byte[] imageBts = bos.toByteArray();
        InputStream in = new ByteArrayInputStream(imageBts);
        return in;
    }
}