com.google.cloud.storage

Class Blob

java.lang.Object

com.google.cloud.storage.BlobInfo

com.google.cloud.storage.Blob

All Implemented Interfaces:

Serializable

public class Blob
extends BlobInfo

A Google cloud storage object.

Objects of this class are immutable. Operations that modify the blob like update(com.google.cloud.storage.Storage.BlobTargetOption...) and copyTo(com.google.cloud.storage.BlobId, com.google.cloud.storage.Blob.BlobSourceOption...) return a new object. To get a Blob object with the most recent information use reload(com.google.cloud.storage.Blob.BlobSourceOption...). Blob adds a layer of service-related functionality over BlobInfo.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Blob.BlobSourceOption Class for specifying blob source options when Blob methods are used.
static class	Blob.Builder Builder for Blob.

Nested classes/interfaces inherited from class com.google.cloud.storage.BlobInfo

BlobInfo.ImmutableEmptyMap<K,V>

Method Summary

Methods

Modifier and Type	Method and Description
byte[]	content(Storage.BlobSourceOption... options) Returns this blob's content.
CopyWriter	copyTo(BlobId targetBlob, Blob.BlobSourceOption... options) Sends a copy request for the current blob to the target blob.
CopyWriter	copyTo(String targetBucket, Blob.BlobSourceOption... options) Sends a copy request for the current blob to the target bucket, preserving its name.
CopyWriter	copyTo(String targetBucket, String targetBlob, Blob.BlobSourceOption... options) Sends a copy request for the current blob to the target blob.
boolean	delete(Blob.BlobSourceOption... options) Deletes this blob.
boolean	equals(Object obj)
boolean	exists(Blob.BlobSourceOption... options) Checks if this blob exists.
int	hashCode()
ReadChannel	reader(Blob.BlobSourceOption... options) Returns a ReadChannel object for reading this blob's content.
Blob	reload(Blob.BlobSourceOption... options) Fetches current blob's latest information.
URL	signUrl(long duration, TimeUnit unit, Storage.SignUrlOption... options) Generates a signed URL for this blob.
Storage	storage() Returns the blob's Storage object used to issue requests.
Blob.Builder	toBuilder() Returns a builder for the current blob.
Blob	update(Storage.BlobTargetOption... options) Updates the blob's information.
WriteChannel	writer(Storage.BlobWriteOption... options) Returns a WriteChannel object for writing to this blob.

Methods inherited from class com.google.cloud.storage.BlobInfo

acl, blobId, bucket, builder, builder, builder, builder, builder, cacheControl, componentCount, contentDisposition, contentEncoding, contentLanguage, contentType, crc32c, deleteTime, etag, generatedId, generation, isDirectory, md5, mediaLink, metadata, metageneration, name, owner, selfLink, size, toString, updateTime

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

exists

public boolean exists(Blob.BlobSourceOption... options)

Checks if this blob exists.

Parameters:

options - blob read options

Returns:

true if this blob exists, false otherwise

Throws:

StorageException - upon failure

content

public byte[] content(Storage.BlobSourceOption... options)

Returns this blob's content.

Parameters:

options - blob read options

Throws:

StorageException - upon failure

reload

public Blob reload(Blob.BlobSourceOption... options)

Fetches current blob's latest information. Returns null if the blob does not exist.

Parameters:

options - blob read options

Returns:

a Blob object with latest information or null if not found

Throws:

StorageException - upon failure

update

public Blob update(Storage.BlobTargetOption... options)

Updates the blob's information. Bucket or blob's name cannot be changed by this method. If you want to rename the blob or move it to a different bucket use the copyTo(com.google.cloud.storage.BlobId, com.google.cloud.storage.Blob.BlobSourceOption...) and delete(com.google.cloud.storage.Blob.BlobSourceOption...) operations. A new Blob object is returned. By default no checks are made on the metadata generation of the current blob. If you want to update the information only if the current blob metadata are at their latest version use the metagenerationMatch option: newBlob.update(BlobTargetOption.metagenerationMatch()).

Original metadata are merged with metadata in the provided in this blob. To replace metadata instead you first have to unset them. Unsetting metadata can be done by setting this blob's metadata to null.

Example usage of replacing blob's metadata:

 blob.toBuilder().metadata(null).build().update();
 blob.toBuilder().metadata(newMetadata).build().update();
 
 

Parameters:

options - update options

Returns:

a Blob object with updated information

Throws:

StorageException - upon failure

delete

public boolean delete(Blob.BlobSourceOption... options)

Deletes this blob.

Parameters:

options - blob delete options

Returns:

true if blob was deleted, false if it was not found

Throws:

StorageException - upon failure

copyTo

public CopyWriter copyTo(BlobId targetBlob,
                Blob.BlobSourceOption... options)

Sends a copy request for the current blob to the target blob. Possibly also some of the metadata are copied (e.g. content-type).

Parameters:

targetBlob - target blob's id

options - source blob options

Returns:

a CopyWriter object that can be used to get information on the newly created blob or to complete the copy if more than one RPC request is needed

Throws:

StorageException - upon failure

copyTo

public CopyWriter copyTo(String targetBucket,
                Blob.BlobSourceOption... options)

Sends a copy request for the current blob to the target bucket, preserving its name. Possibly copying also some of the metadata (e.g. content-type).

Parameters:

targetBucket - target bucket's name

options - source blob options

Returns:

a CopyWriter object that can be used to get information on the newly created blob or to complete the copy if more than one RPC request is needed

Throws:

StorageException - upon failure

copyTo

public CopyWriter copyTo(String targetBucket,
                String targetBlob,
                Blob.BlobSourceOption... options)

Sends a copy request for the current blob to the target blob. Possibly also some of the metadata are copied (e.g. content-type).

Parameters:

targetBucket - target bucket's name

targetBlob - target blob's name

options - source blob options

Returns:

a CopyWriter object that can be used to get information on the newly created blob or to complete the copy if more than one RPC request is needed

Throws:

StorageException - upon failure

reader

public ReadChannel reader(Blob.BlobSourceOption... options)

Returns a ReadChannel object for reading this blob's content.

Parameters:

options - blob read options

Throws:

StorageException - upon failure

writer

public WriteChannel writer(Storage.BlobWriteOption... options)

Returns a WriteChannel object for writing to this blob. By default any md5 and crc32c values in the current blob are ignored unless requested via the BlobWriteOption.md5Match and BlobWriteOption.crc32cMatch options.

Parameters:

options - target blob options

Throws:

StorageException - upon failure

signUrl

public URL signUrl(long duration,
          TimeUnit unit,
          Storage.SignUrlOption... options)

Generates a signed URL for this blob. If you want to allow access for a fixed amount of time to this blob, you can use this method to generate a URL that is only valid within a certain time period. This is particularly useful if you don't want publicly accessible blobs, but also don't want to require users to explicitly log in. Signing a URL requires a service account signer. If a AuthCredentials.ServiceAccountAuthCredentials or an AuthCredentials.AppEngineAuthCredentials was passed to ServiceOptions.Builder.authCredentials(AuthCredentials) or the default credentials are being used and the environment variable GOOGLE_APPLICATION_CREDENTIALS is set, then signUrl will use that credentials to sign the URL. If the credentials passed to StorageOptions do not implement ServiceAccountSigner (this is the case for Compute Engine credentials and Google Cloud SDK credentials) then signUrl will throw an IllegalStateException unless an implementation of ServiceAccountSigner is passed using the Storage.SignUrlOption.signWith(ServiceAccountSigner) option.

A service account signer is looked for in the following order:

1. The signer passed with the option Storage.SignUrlOption.signWith(ServiceAccountSigner)
2. The credentials passed to ServiceOptions.Builder.authCredentials(AuthCredentials)
3. The default credentials, if no credentials were passed to StorageOptions

Example usage of creating a signed URL that is valid for 2 weeks, using the default credentials for signing the URL:

 blob.signUrl(14, TimeUnit.DAYS);
 

Example usage of creating a signed URL passing the Storage.SignUrlOption.signWith(ServiceAccountSigner) option, that will be used for signing the URL:

 blob.signUrl(14, TimeUnit.DAYS, SignUrlOption.signWith(
     AuthCredentials.createForJson(new FileInputStream("/path/to/key.json"))));
 

Parameters:

duration - time until the signed URL expires, expressed in unit. The finer granularity supported is 1 second, finer granularities will be truncated

unit - time unit of the duration parameter

options - optional URL signing options

Returns:

a signed URL for this blob and the specified options

Throws:

IllegalStateException - if Storage.SignUrlOption.signWith(ServiceAccountSigner) was not used and no implementation of ServiceAccountSigner was provided to StorageOptions

IllegalArgumentException - if SignUrlOption.withMd5() option is used and blobInfo.md5() is null

IllegalArgumentException - if SignUrlOption.withContentType() option is used and blobInfo.contentType() is null

ServiceAccountSigner.SigningException - if the attempt to sign the URL failed

See Also:

Signed-URLs

storage

public Storage storage()

Returns the blob's Storage object used to issue requests.

toBuilder

public Blob.Builder toBuilder()

Description copied from class: BlobInfo

Returns a builder for the current blob.

Overrides:

toBuilder in class BlobInfo

equals

public final boolean equals(Object obj)

Overrides:

equals in class BlobInfo

hashCode

public final int hashCode()

Overrides:

hashCode in class BlobInfo