Package com.google.appengine.api.blobstore

Class BlobInfoFactory

java.lang.Object

com.google.appengine.api.blobstore.BlobInfoFactory

public class BlobInfoFactory
extends Object

BlobInfoFactory provides a trivial interface for retrieving BlobInfo metadata.

BlobInfo metadata is stored in read-only __BlobInfo__ entities in the datastore. This class provides an easy way to access these entities. For more complex queries, you can use the datastore directly.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	CONTENT_TYPE
static final String	CREATION
static final String	FILENAME
static final String	GS_OBJECT_NAME
static final String	KIND
static final String	MD5_HASH
static final String	SIZE

Constructor Summary

Constructors

Constructor	Description
BlobInfoFactory()	Creates a BlobInfoFactory that uses the default implementation of DatastoreService.
BlobInfoFactory(DatastoreService datastoreService)	Creates a BlobInfoFactory with the specified implementation of DatastoreService.

Method Summary

Modifier and Type	Method	Description
BlobInfo	createBlobInfo(Entity entity)	Creates a BlobInfo by extracting content from the specified Entity.
@Nullable BlobInfo	loadBlobInfo(BlobKey blobKey)	Loads the BlobInfo metadata for blobKey.
Iterator<BlobInfo>	queryBlobInfos()	Queries for BlobInfo instances, beginning with the BlobKey that appears first in lexicographic order.
Iterator<BlobInfo>	queryBlobInfosAfter(@Nullable BlobKey previousBlob)	Queries for BlobInfo instances, beginning at the blob following previousBlob in lexicographic order.

Methods inherited from class java.lang.Object

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

Field Details

KIND

public static final String KIND

See Also:

• Constant Field Values

CONTENT_TYPE

public static final String CONTENT_TYPE

See Also:

• Constant Field Values

CREATION

public static final String CREATION

See Also:

• Constant Field Values

FILENAME

public static final String FILENAME

See Also:

• Constant Field Values

SIZE

public static final String SIZE

See Also:

• Constant Field Values

MD5_HASH

public static final String MD5_HASH

See Also:

• Constant Field Values

GS_OBJECT_NAME

public static final String GS_OBJECT_NAME

See Also:

• Constant Field Values

Constructor Details

BlobInfoFactory

public BlobInfoFactory()

Creates a BlobInfoFactory that uses the default implementation of DatastoreService.

BlobInfoFactory

public BlobInfoFactory(DatastoreService datastoreService)

Creates a BlobInfoFactory with the specified implementation of DatastoreService.

Method Details

loadBlobInfo

public @Nullable BlobInfo loadBlobInfo(BlobKey blobKey)

Loads the BlobInfo metadata for blobKey. Returns null if no matching blob is found.

queryBlobInfos

public Iterator<BlobInfo> queryBlobInfos()

Queries for BlobInfo instances, beginning with the BlobKey that appears first in lexicographic order.

queryBlobInfosAfter

public Iterator<BlobInfo> queryBlobInfosAfter(@Nullable BlobKey previousBlob)

Queries for BlobInfo instances, beginning at the blob following previousBlob in lexicographic order. If previousBlob is null, the first blob will be returned.

This is useful for displaying discrete pages of blobs.

createBlobInfo

public BlobInfo createBlobInfo(Entity entity)

Creates a BlobInfo by extracting content from the specified Entity.