java 图片生成缩略图后，转化成流

public class ImageUtils {
/**
*
* @param in1
*            文件流
* @param uploadFileName
*            文件名称
* @param wide
*            宽
* @param high
*            高
* @return
* @throws IOException
*/
public static InputStream thumbnailImage(InputStream in1, String fileName, int wide, int high) throws IOException {
InputStream inThumb = null;

String types = Arrays.toString(ImageIO.getReaderFormatNames()).replace("]", ",");
String suffix = null;
if (fileName.indexOf(".") > -1) {
suffix = fileName.substring(fileName.lastIndexOf(".") + 1);
}// 类型和图片后缀全部小写，然后判断后缀是否合法
if (suffix == null || types.toLowerCase().indexOf(suffix.toLowerCase() + ",") < 0) {
return null;
}
Image img = ImageIO.read(in1);
BufferedImage bi = new BufferedImage(wide, high, BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
g.drawImage(img, 0, 0, wide, high, Color.LIGHT_GRAY, null);
g.dispose();
ByteArrayOutputStream bs = new ByteArrayOutputStream();
ImageOutputStream imOut;
imOut = ImageIO.createImageOutputStream(bs);
ImageIO.write(bi, "jpg", imOut);
inThumb = new ByteArrayInputStream(bs.toByteArray());
return inThumb;
}
}