初始化

//根據OS區分實現　System.getProperty("os.name").toLowerCase();
 Utils.isWindows() ? new WindowsFileSystem(this) : new FileSystemImpl(this);

異步操作實現

FileSystemImpl 內部類 BlockingAction, 使用internalBlocking Pool 執行文件阻塞操作, xxxBlocking相關方法在當前主線程操作造成阻塞，盡量避免

protected abstract class BlockingAction<T> implements Action<T> {

    
 
private final Handler<AsyncResult<T>> handler;//回調　handler
    protected final ContextImpl context;//上下文，作用:處理完成回調到同一線程

    public BlockingAction(Handler<AsyncResult<T>> handler) {
      this.handler = handler;
      this.context = vertx.getOrCreateContext();
    }
    
    
 
/**
     *  Run the blocking action using a thread from the worker pool.
     */
    public void run() {
      context.executeBlocking(this, handler);　//使用　internalBlocking　Pool執行任務
    }
 }

AsyncFileImpl

FileSystemImpl 的open方法返回的AsyncFileImpl，記住調用close方法，防止文件句柄泄露, linux可使用 lsof 工具查看當前file descriptor情況

AsyncFileImpl(VertxInternal vertx, String path, OpenOptions options, ContextImpl context) {
    if (!options.isRead() && !options.isWrite()) {
      throw new FileSystemException("Cannot open file for neither reading nor writing");
    }
    this.vertx = vertx;
    Path file = Paths.get(path);
    /**定義open屬性*/
    HashSet<OpenOption> opts = new HashSet<>();
    if (options.isRead()) opts.add(StandardOpenOption.READ);
    if (options.isWrite()) opts.add(StandardOpenOption.WRITE);
    if (options.isCreate()) opts.add(StandardOpenOption.CREATE);
    if (options.isCreateNew()) opts.add(StandardOpenOption.CREATE_NEW);
    if (options.isSync()) opts.add(StandardOpenOption.SYNC);
    if (options.isDsync()) opts.add(StandardOpenOption.DSYNC);
    if (options.isDeleteOnClose()) opts.add(StandardOpenOption.DELETE_ON_CLOSE);
    if (options.isSparse()) opts.add(StandardOpenOption.SPARSE);
    if (options.isTruncateExisting())   opts.add(StandardOpenOption.TRUNCATE_EXISTING);
    try {
    　//獲取文件權限字符　linux 下 ls -al　文件權限標識 rwx
      if (options.getPerms() != null) {
        //將權限字符轉化為FileAttribute屬性
        FileAttribute<?> attrs = PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString(options.getPerms()));
        
        /**使用worker　Pool,而不是用默認的Executors.newCachedThreadPool(threadFactory),
            原則:vertx使用少量線程處理大並發,吞吐量優先*/
        ch = AsynchronousFileChannel.open(file, opts, vertx.getWorkerPool(), attrs);
      } else {
        ch = AsynchronousFileChannel.open(file, opts, vertx.getWorkerPool());
      }
      //屬性為"追加"獲取大小做為　write index
      if (options.isAppend()) writePos = ch.size();
    } catch (IOException e) {
      throw new FileSystemException(e);
    }
    //上下文，作用:處理完成回調到同一線程
    this.context = context;
}

vertx實例的fileSystem文件系統模塊