复制InputStream流的方法

private static InputStream cloneInputStream(InputStream input) {
    try {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        while ((len = input.read(buffer)) > -1) {
            baos.write(buffer, 0, len);
        }
        baos.flush();
        return new ByteArrayInputStream(baos.toByteArray());
    } catch (IOException e) {
        e.printStackTrace();
        return null;
    }
}