[Alfresco ] How to update content with ContentWriter class

此問題欲解決要利用ContentWriter變更Node的內容， 不是指新增版本的方式，目前尚未用到，待驗證 :)

ContentWriter contentWriter = contentService.getWriter(nodeCurrentLogFile, ContentModel.PROP_CONTENT, true);
contentWriter.setMimetype("text/plain");
FileChannel fileChannel = contentWriter.getFileChannel(false);
ByteBuffer bf = ByteBuffer.wrap(logLine.getBytes());
fileChannel.position(contentWriter.getSize());
fileChannel.write(bf);
fileChannel.force(false);
fileChannel.close();