com.google.appengine.api.files.dev
Class FileMetadata

java.lang.Object
  com.google.appengine.api.files.dev.FileMetadata

Direct Known Subclasses:

BlobstoreFile, GSFile

public abstract class FileMetadata
extends java.lang.Object

This class represents a single file stored by the local file service. This class is abstract. There are concrete subclasses corresponding to each of the concrete backend storage repositories.

Nested Class Summary

static class	FileMetadata.LockState
static class	FileMetadata.OpenState The state of a file in a particular session.

Field Summary

protected java.lang.String	appendName The name of the appendable version of this unfinalized file.
protected ContentType	contentType
protected java.lang.String	currentSequenceKey If this instance is for writing and it has not yet been finalized, then this variable stores the current sequence key
protected boolean	finalized
protected java.lang.String	readName The name of the readable version of this file once it is finalized.
protected java.io.ByteArrayOutputStream	tempBytes If this instance is for writing and it has not yet been finalized, then this variable stores the current bytes.

Constructor Summary

FileMetadata(java.lang.String readName, java.lang.String appendName, ContentType contentType)

Method Summary

void	append(AppendRequest request) Handle an append request
protected static void	checkParameters(java.util.Map<java.lang.String,java.lang.String> parameters, java.lang.String... names)
protected static long	copy(java.io.InputStream from, java.io.OutputStream to, long maxBytes) Copies maxBytes bytes from the input stream to the output stream.
java.lang.String	getAppendName()
ContentType	getContentType()
protected abstract java.io.InputStream	getInputStream()
FileMetadata.LockState	getLockState(Session session)
FileMetadata.OpenState	getOpenState(Session session)
protected abstract java.io.OutputStream	getOutputStream()
boolean	isFinalized()
boolean	isOpenInDifferentSession(Session session)
void	lock(Session session)
static FileMetadata	newReadableInstance(LocalFileService localFileService, Clock clock, ParsedFileName parsedName) Returns a new instance of FileMetadata if possible.
ByteString	read(ReadRequest request) Handle a Read request
void	setFinalized()
void	setState(FileMetadata.OpenState state, Session session)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

contentType

protected ContentType contentType

finalized

protected boolean finalized

readName

protected final java.lang.String readName

The name of the readable version of this file once it is finalized.

appendName

protected final java.lang.String appendName

The name of the appendable version of this unfinalized file.

currentSequenceKey

protected java.lang.String currentSequenceKey

If this instance is for writing and it has not yet been finalized, then this variable stores the current sequence key

tempBytes

protected final java.io.ByteArrayOutputStream tempBytes

If this instance is for writing and it has not yet been finalized, then this variable stores the current bytes. These bytes will be copied to the remote file during finalization.

Constructor Detail

FileMetadata

public FileMetadata(java.lang.String readName,
                    java.lang.String appendName,
                    ContentType contentType)

Method Detail

getAppendName

public java.lang.String getAppendName()

setFinalized

public void setFinalized()

isFinalized

public boolean isFinalized()

getContentType

public ContentType getContentType()

lock

public void lock(Session session)

getLockState

public FileMetadata.LockState getLockState(Session session)

setState

public void setState(FileMetadata.OpenState state,
                     Session session)

getOpenState

public FileMetadata.OpenState getOpenState(Session session)

isOpenInDifferentSession

public boolean isOpenInDifferentSession(Session session)

read

public ByteString read(ReadRequest request)

Handle a Read request

Parameters:

request - the request

Returns:

A ByteString containing the read bytes

append

public void append(AppendRequest request)

Handle an append request

Parameters:

request - the request

getInputStream

protected abstract java.io.InputStream getInputStream()
                                               throws java.io.IOException

Throws:

java.io.IOException

getOutputStream

protected abstract java.io.OutputStream getOutputStream()
                                                 throws java.io.IOException

Throws:

java.io.IOException

checkParameters

protected static void checkParameters(java.util.Map<java.lang.String,java.lang.String> parameters,
                                      java.lang.String... names)

copy

protected static long copy(java.io.InputStream from,
                           java.io.OutputStream to,
                           long maxBytes)
                    throws java.io.IOException

Copies maxBytes bytes from the input stream to the output stream.

Throws:

java.io.IOException

newReadableInstance

public static FileMetadata newReadableInstance(LocalFileService localFileService,
                                               Clock clock,
                                               ParsedFileName parsedName)

Returns a new instance of FileMetadata if possible. This method is called in response to an Open-for-Read request in the case that no meta-data is found for the requested file in the in-memory cache. If it is determined that the given file name corresponds to an existing, finalized file, then an instance of FileMetadata will be returned. Otherwise null will be returned.

Returns:

An instance of FileMetadata or null if no corresponding entity could be found in the datastore.