Java从内存流中读取byte数组

/**
 * 获取客户提交上来的数据
 * @param request
 * @return
 */
private byte[] getData(HttpServletRequest request) {
    try {
        // byte[] bs = new byte[request.getContentLength()];
        // request.getInputStream().read(bs);
        // return bs;

        ServletInputStream sis = request.getInputStream();
        ByteArrayOutputStream swapStream = new ByteArrayOutputStream();

        byte[] buff = new byte[100];
        int rc = 0;
        while ((rc = sis.read(buff, 0, 100)) > 0) {
            swapStream.write(buff, 0, rc);
        }
        byte[] in2b = swapStream.toByteArray();
        return in2b;
    } catch (IOException e) {
        LogHelper.logger.error("接收数据失败", e);
    }
    return new byte[0];
}