com.google.appengine.api.files
Class AppEngineFile

java.lang.Object
  com.google.appengine.api.files.AppEngineFile

All Implemented Interfaces:

java.io.Serializable

public class AppEngineFile
extends java.lang.Object
implements java.io.Serializable

An AppEngineFile represents a file in one of the Google App Engine file systems.

A file has a path of the form /<fileSystem>/<namePart> . The path consists of a file system which is one of several identifiers for a Google App Engine file system, and a name part wich is an arbitrary String. For example "/blobstore/Aie7uHVwtvM" is a path in which "blobstore" is the file system and "Aie7uHVwtvM" is the name part.

The enum AppEngineFile.FileSystem represents the available file systems. Each file system has particular attributes regarding permanence, reliability availability, and cost.

In the current release of Google App Engine, BLOBSTORE and GS are the only available file systems. These file systems store files as blobs in the BlobStore and in Google Storage respectively.

App Engine files may only be accessed using a particular access pattern: Newly created files may be appended to until they are finalized. After a file is finalized it may be read, but it may no longer be written.

To create a new BLOBSTORE file use FileService.createNewBlobFile(String). This returns an instance of AppEngineFile with a FileSystem of BLOBSTORE.

To create a new GS file use FileService.createNewGSFile(GSFileOptions). This returns an instance of AppEngineFile with a FileSystem of GS. This instance cannot be used for reading. For a full file lifecycle example, see FileService.

See Also:

Serialized Form

Nested Class Summary

static class

AppEngineFile.FileSystem Represents the back-end storage location of a file.

Constructor Summary

AppEngineFile(AppEngineFile.FileSystem fileSystem, java.lang.String namePart)
Constructs an AppEngineFile from the given data

AppEngineFile(java.lang.String fullPath)
Constructs an AppEngineFile from the given data

Method Summary

AppEngineFile.FileSystem	getFileSystem() Returns the file system of the file.
java.lang.String	getFullPath() Returns the full path of the file.
java.lang.String	getNamePart() Returns the name part of the file.
boolean	isReadable() Returns a boolean indicating whether or not this instance can be used for reading.
boolean	isWritable() Returns a boolean indicating whether or not this instance can be used for writing.
java.lang.String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AppEngineFile

public AppEngineFile(AppEngineFile.FileSystem fileSystem,
                     java.lang.String namePart)

Constructs an AppEngineFile from the given data

Parameters:

fileSystem - a non-null FileSystem.

namePart - a non-null name part. Warning: Do not use the full path here.

AppEngineFile

public AppEngineFile(java.lang.String fullPath)

Constructs an AppEngineFile from the given data

Parameters:

fullPath - a non-null full path. Warning: Do not use a name part here.

Method Detail

getNamePart

public java.lang.String getNamePart()

Returns the name part of the file.

getFullPath

public java.lang.String getFullPath()

Returns the full path of the file.

getFileSystem

public AppEngineFile.FileSystem getFileSystem()

Returns the file system of the file.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

isWritable

public boolean isWritable()

Returns a boolean indicating whether or not this instance can be used for writing.

isReadable

public boolean isReadable()

Returns a boolean indicating whether or not this instance can be used for reading.