生成验证码图片

public class SecurityImage {
    
    /**
     * 生成验证码图片
     * @param securityCode   验证码字符
     * @return  BufferedImage  图片
     */
    public static BufferedImage createImage(String securityCode){
        
        //验证码长度
        int codeLength=securityCode.length();
        //字体大小
        int fSize = 15;
        int fWidth = fSize + 1;
        //图片宽度
        int width = codeLength * fWidth + 16 ;
        //图片高度
        int height = fSize * 2 + 5;
        
        //图片
        BufferedImage image=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics g=image.createGraphics();
        
        //设置背景色
        g.setColor(Color.WHITE);
        //填充背景
        g.fillRect(0, 0, width, height);
        
        //设置边框颜色
        g.setColor(Color.LIGHT_GRAY);
        //边框字体样式
        g.setFont(new Font("Arial", Font.BOLD, height));
        //绘制边框
        g.drawRect(0, 0, width - 1, height -1);
        
        //绘制噪点
        Random rand = new Random();
        //设置噪点颜色
        g.setColor(Color.LIGHT_GRAY);
        for(int i = 0;i < codeLength * 16;i++){
            int x = rand.nextInt(width);
            int y = rand.nextInt(height);
            //绘制1*1大小的矩形
            g.drawRect(x, y, 1, 1);
        }
        g.setColor(Color.black);
       /* for(int i = 0;i < 8;i++){
            int x = rand.nextInt(width);
            int y = rand.nextInt(height);
            int x2 = rand.nextInt(width);
            int y2 = rand.nextInt(height);
            g.drawLine(x, y, x2, y2);
        }*/
        
        //绘制验证码
        int codeY = height - 10;  
        
        //设置字体颜色和样式
        
        g.setFont(new Font("Georgia", Font.BOLD, fSize+10));
        for(int i = 0; i < codeLength;i++){
           int x = rand.nextInt(256);
           int y= rand.nextInt(256);
           int z = rand.nextInt(256);
           g.setColor(new Color(x,y,z));
            g.drawString(String.valueOf(securityCode.charAt(i)), i * 16 + 10, codeY);
        }
        //关闭资源
        g.dispose();
        
        return image;
    }
    
    /**
     * 返回验证码图片的流格式
     * @param securityCode  验证码
     * @return ByteArrayInputStream 图片流
     */
    public static BufferedImage getImageAsInputStream(String securityCode){
        
        BufferedImage image = createImage(securityCode);
        return image;
    }
    
    /**
     * 将BufferedImage转换成ByteArrayInputStream
     * @param image  图片
     * @return ByteArrayInputStream 流
     */
    private static ByteArrayInputStream convertImageToStream(BufferedImage image){
        
        ByteArrayInputStream inputStream = null;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        JPEGImageEncoder jpeg = JPEGCodec.createJPEGEncoder(bos);
        try {
            jpeg.encode(image);
            byte[] bts = bos.toByteArray();
            inputStream = new ByteArrayInputStream(bts);
        } catch (ImageFormatException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return inputStream;
    }
}