记录java ftp下载图片只有96KB的问题

public InputStream  downloadFile(String path) {
    if(StringUtils.isBlank(path)) {
        return null;
    }
        
    connnect();
        
    try {
        return ftpClient.retrieveFileStream(path);
    } catch (IOException e) {
        e.printStackTrace();
        throw new BusinessException("ftp下载文件失败");
    }finally {
        disconnnect();
    }
}

public byte[]  downloadFile1(String path) {
    byte[] byteArray1=new byte[0];
    if(StringUtils.isBlank(path)) {
        return null;
    }
        
    connnect();
        
    try {
        InputStream  is  =ftpClient.retrieveFileStream(path);
        ByteArrayOutputStream out=new ByteArrayOutputStream(); 
        int firstByte = -1;
        do {
            firstByte = is.read();
            int length = is.available();
            byte[] byteArray = new byte[length+1];
            byteArray[0] = (byte)firstByte;
            is.read(byteArray,1,length);
            out.write(byteArray);
        } while (firstByte>-1); 
        byteArray1= out.toByteArray();
            
        is.close();
        ftpClient.completePendingCommand();
    } catch (IOException e) {
        e.printStackTrace();
        throw new BusinessException("ftp下载文件失败");
    }finally {
        disconnnect();
    }
    return byteArray1;
}