import org.apache.commons.net.ftp.FTPClient; //导入方法依赖的package包/类

/**

* A stream obtained via this call must be closed before using other APIs of

* this class or else the invocation will block.

*/

@Override

public FSDataOutputStream create(Path file, FsPermission permission,

boolean overwrite, int bufferSize, short replication, long blockSize,

Progressable progress) throws IOException {

final FTPClient client = connect();

Path workDir = new Path(client.printWorkingDirectory());

Path absolute = makeAbsolute(workDir, file);

FileStatus status;

try {

status = getFileStatus(client, file);

} catch (FileNotFoundException fnfe) {

status = null;

}

if (status != null) {

if (overwrite && !status.isDirectory()) {

delete(client, file, false);

} else {

disconnect(client);

throw new FileAlreadyExistsException("File already exists: " + file);

}

}

Path parent = absolute.getParent();

if (parent == null || !mkdirs(client, parent, FsPermission.getDirDefault())) {

parent = (parent == null) ? new Path("/") : parent;

disconnect(client);

throw new IOException("create(): Mkdirs failed to create: " + parent);

}

client.allocate(bufferSize);

// Change to parent directory on the server. Only then can we write to the

// file on the server by opening up an OutputStream. As a side effect the

// working directory on the server is changed to the parent directory of the

// file. The FTP client connection is closed when close() is called on the

// FSDataOutputStream.

client.changeWorkingDirectory(parent.toUri().getPath());

FSDataOutputStream fos = new FSDataOutputStream(client.storeFileStream(file

.getName()), statistics) {

@Override

public void close() throws IOException {

super.close();

if (!client.isConnected()) {

throw new FTPException("Client not connected");

}

boolean cmdCompleted = client.completePendingCommand();

disconnect(client);

if (!cmdCompleted) {

throw new FTPException("Could not complete transfer, Reply Code - "

+ client.getReplyCode());

}

}

};

if (!FTPReply.isPositivePreliminary(client.getReplyCode())) {

// The ftpClient is an inconsistent state. Must close the stream

// which in turn will logout and disconnect from FTP server

fos.close();

throw new IOException("Unable to create file: " + file + ", Aborting");

}

return fos;

}