com.couchbase.lite

Class Blob

java.lang.Object

com.couchbase.lite.Blob

All Implemented Interfaces:

FLEncodable

public final class Blob
extends Object
implements FLEncodable

A Couchbase Lite Blob. A Blob appears as a property of a Document and contains arbitrary binary data, tagged with MIME type. Blobs can be arbitrarily large, although some operations may require that the entire content be loaded into memory. The containing document's JSON contains only the Blob's metadata (type, length and digest). The data itself is stored in a file whose name is the content digest (like git).

Field Summary

Fields

Modifier and Type	Field and Description
static String	ENCODER_ARG_DB
static String	ENCODER_ARG_QUERY_PARAM

Constructor Summary

Constructors

Constructor and Description
Blob(String contentType, byte[] content) Construct a Blob with the given in-memory data.
Blob(String contentType, InputStream stream) Construct a Blob with the given stream of data.
Blob(String contentType, URL fileURL) Construct a Blob with the content of a file.

Method Summary

Modifier and Type	Method and Description
String	digest() The cryptographic digest of this Blob's contents, which uniquely identifies it.
void	encodeTo(FLEncoder encoder) This method is not part of the public API: Do not use it.
boolean	equals(Object o) Compare for equality.
byte[]	getContent() Gets the contents of this blob as in in-memory byte array.
InputStream	getContentStream() Get a the contents of this blob as a stream.
String	getContentType() Return the type of of the content this blob contains.
Map<String,Object>	getProperties() Get the blob metadata
int	hashCode() Get the blob hash code.
static boolean	isBlob(Map<String,?> props)
long	length() The number of byte of content this blob contains.
String	toJSON()
String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

ENCODER_ARG_DB

public static final String ENCODER_ARG_DB

See Also:

Constant Field Values

ENCODER_ARG_QUERY_PARAM

public static final String ENCODER_ARG_QUERY_PARAM

See Also:

Constant Field Values

Constructor Detail

Blob

public Blob(@NonNull
            String contentType,
            @NonNull
            byte[] content)

Construct a Blob with the given in-memory data.

Parameters:

contentType - The type of content this Blob will represent

content - The data that this Blob will contain

Blob

public Blob(@NonNull
            String contentType,
            @NonNull
            InputStream stream)

Construct a Blob with the given stream of data. The passed stream will be closed when it is copied either to memory (see getContent) or to the database. If it is closed before that, by client code, the attempt to store the blob will fail. The converse is also true: the stream for a blob that is not saved or copied to memory will not be closed (except during garbage collection).

Parameters:

contentType - The type of content this Blob will represent

stream - The stream of data that this Blob will consume

Blob

public Blob(@NonNull
            String contentType,
            @NonNull
            URL fileURL)
     throws IOException

Construct a Blob with the content of a file. The blob can then be added as a property of a Document. This constructor creates a stream that is not closed until the blob is stored in the db, or copied to memory (except by garbage collection).

Parameters:

contentType - The type of content this Blob will represent

fileURL - A URL to a file containing the data that this Blob will represent.

Throws:

IOException - on failure to open the file URL

Method Detail

isBlob

public static boolean isBlob(@Nullable
                             Map<String,?> props)

getContent

@Nullable
public byte[] getContent()

Gets the contents of this blob as in in-memory byte array. Using this method will cause the entire contents of the blob to be read into memory!

Returns:

the contents of a Blob as a block of memory

getContentStream

@Nullable
public InputStream getContentStream()

Get a the contents of this blob as a stream. The caller is responsible for closing the stream returned by this call. Closing or deleting the database before this call completes may cause it to fail. When called on a blob created from a stream (or a file path), this method will return null!

Returns:

a stream of of this blobs contents; null if none exists or if this blob was initialized with a stream

getContentType

@NonNull
public String getContentType()

Return the type of of the content this blob contains. By convention this is a MIME type.

Returns:

the type of blobContent

toJSON

@NonNull
public String toJSON()

length

public long length()

The number of byte of content this blob contains.

Returns:

The length of the blob or 0 if initialized with a stream.

digest

@Nullable
public String digest()

The cryptographic digest of this Blob's contents, which uniquely identifies it.

Returns:

The cryptographic digest of this blob's contents; null if the content has not been saved in a database

getProperties

@NonNull
public Map<String,Object> getProperties()

Get the blob metadata

Returns:

metadata for this Blob

encodeTo

@Volatile
public void encodeTo(@NonNull
                               FLEncoder encoder)

This method is not part of the public API: Do not use it.

Specified by:

encodeTo in interface FLEncodable

Parameters:

encoder - The FLEncoder to which to encode this object.

toString

@NonNull
public String toString()

Returns a string representation of the object.

Overrides:

toString in class Object

Returns:

a string representation of the object

hashCode

public int hashCode()

Get the blob hash code. This method is quite expensive. Also, when called on a blob created from a stream (or a file path), it will cause the entire contents of that stream to be read into memory!

Overrides:

hashCode in class Object

Returns:

hash code for the object

equals

public boolean equals(Object o)

Compare for equality. This method is quite expensive. Also, when called on a blob created from a stream (or a file path), it will cause the entire contents of that stream to be read into memory!

Overrides:

equals in class Object

Returns:

true if this object is the same as that one.