com.google.cloud.dataflow.sdk.util

Interface IOChannelFactory

All Known Implementing Classes:

FileIOChannelFactory, GcsIOChannelFactory

public interface IOChannelFactory

Defines a factory for working with read and write channels.

Channels provide an abstract API for IO operations.

See Java NIO Channels

Method Summary

Modifier and Type	Method and Description
WritableByteChannel	create(String spec, String mimeType) Returns a write channel for the given specification.
long	getSizeBytes(String spec) Returns the size in bytes for the given specification.
boolean	isReadSeekEfficient(String spec) Returns true if the channel created when invoking method open(java.lang.String) for the given file specification is guaranteed to be of type SeekableByteChannel and if seeking into positions of the channel is recommended.
Collection<String>	match(String spec) Matches a specification, which may contain globs, against available resources.
ReadableByteChannel	open(String spec) Returns a read channel for the given specification.
String	resolve(String path, String other) Resolve the given other against the path.

Method Detail

match

Collection<String> match(String spec)
                  throws IOException

Matches a specification, which may contain globs, against available resources.

Glob handling is dependent on the implementation. Implementations should all support globs in the final component of a path (eg /foo/bar/*.txt), however they are not required to support globs in the directory paths.

The result is the (possibly empty) set of specifications that match.

Throws:

IOException

open

ReadableByteChannel open(String spec)
                  throws IOException

Returns a read channel for the given specification.

The specification is not expanded; it is used verbatim.

If seeking is supported, then this returns a SeekableByteChannel.

Throws:

IOException

create

WritableByteChannel create(String spec,
                           String mimeType)
                    throws IOException

Returns a write channel for the given specification.

The specification is not expanded; is it used verbatim.

Throws:

IOException

getSizeBytes

long getSizeBytes(String spec)
           throws IOException

Returns the size in bytes for the given specification.

The specification is not expanded; it is used verbatim.

FileNotFoundException will be thrown if the resource does not exist.

Throws:

IOException

isReadSeekEfficient

boolean isReadSeekEfficient(String spec)
                     throws IOException

Returns true if the channel created when invoking method open(java.lang.String) for the given file specification is guaranteed to be of type SeekableByteChannel and if seeking into positions of the channel is recommended. Returns false if the channel returned is not a SeekableByteChannel. May return false even if the channel returned is a SeekableByteChannel, if seeking is not efficient for the given file specification.

Only efficiently seekable files can be split into offset ranges.

The specification is not expanded; it is used verbatim.

Throws:

IOException

resolve

String resolve(String path,
               String other)
        throws IOException

Resolve the given other against the path.

If the other parameter is an absolute path then this method trivially returns other. If other is an empty path then this method trivially returns the given path. Otherwise this method considers the given path to be a directory and resolves the other path against this path. In the simplest case, the other path does not have a root component, in which case this method joins the other path to the given path and returns a resulting path that ends with the other path. Where the other path has a root component then resolution is highly implementation dependent and therefore unspecified.

Throws:

IOException