Blob (GCloud Java storage 0.2.8 API)

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(Blob.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, createTime, 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.
    Example of checking if the blob exists.
```
 boolean exists = blob.exists();
 if (exists) {
   // the blob exists
 } else {
   // the blob was not found
 }
 
```
    Parameters:
    options - blob read options
    
    Returns:
    true if this blob exists, false otherwise
    
    Throws:
    
    StorageException - upon failure
  - content
```
public byte[] content(Blob.BlobSourceOption... options)
```
    Returns this blob's content.
    Example of reading all bytes of the blob, if its generation matches the BlobInfo.generation() value, otherwise a StorageException is thrown.
```
 byte[] content = blob.content(BlobSourceOption.generationMatch());
 
```
    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.
    Example of getting the blob's latest information, if its generation does not match the BlobInfo.generation() value, otherwise a StorageException is thrown.
```
 Blob latestBlob = blob.reload(BlobSourceOption.generationNotMatch());
 if (latestBlob == null) {
   // the blob was not found
 }
 
```
    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 of replacing blob's metadata.
```
 Map<String, String> newMetadata = new HashMap<>();
 newMetadata.put("key", "value");
 blob.toBuilder().metadata(null).build().update();
 Blob updatedBlob = 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.
    Example of deleting the blob, if its generation matches the BlobInfo.generation() value, otherwise a StorageException is thrown.
```
 boolean deleted = blob.delete(BlobSourceOption.generationMatch());
 if (deleted) {
   // the blob was deleted
 } else {
   // the blob was not found
 }
 
```
    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).
    Example of copying the blob to a different bucket with a different name.
```
 String bucketName = "my_unique_bucket";
 String blobName = "copy_blob_name";
 CopyWriter copyWriter = blob.copyTo(BlobId.of(bucketName, blobName));
 Blob copiedBlob = copyWriter.result();
 
```
    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).
    Example of copying the blob to a different bucket, keeping the original name.
```
 String bucketName = "my_unique_bucket";
 CopyWriter copyWriter = blob.copyTo(bucketName);
 Blob copiedBlob = copyWriter.result();
 
```
    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).
    Example of copying the blob to a different bucket with a different name.
```
 String bucketName = "my_unique_bucket";
 String blobName = "copy_blob_name";
 CopyWriter copyWriter = blob.copyTo(bucketName, blobName);
 Blob copiedBlob = copyWriter.result();
 
```
    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.
    Example of reading the blob's content through a reader.
```
 try (ReadChannel reader = blob.reader()) {
   ByteBuffer bytes = ByteBuffer.allocate(64 * 1024);
   while (reader.read(bytes) > 0) {
     bytes.flip();
     // do something with bytes
     bytes.clear();
   }
 }
 
```
    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.
    Example of writing the blob's content through a writer.
```
 byte[] content = "Hello, World!".getBytes(UTF_8);
 try (WriteChannel writer = blob.writer()) {
   try {
     writer.write(ByteBuffer.wrap(content, 0, content.length));
   } catch (Exception ex) {
     // handle exception
   }
 }
 
```
    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 of creating a signed URL for the blob that is valid for 2 weeks, using the default credentials for signing the URL.
```
 URL signedUrl = blob.signUrl(14, TimeUnit.DAYS);
 
```
    Example of creating a signed URL for the blob passing the Storage.SignUrlOption.signWith(ServiceAccountSigner) option, that will be used to sign the URL.
```
 String keyPath = "/path/to/key.json";
 URL signedUrl = blob.signUrl(14, TimeUnit.DAYS, SignUrlOption.signWith(
     AuthCredentials.createForJson(new FileInputStream(keyPath))));
 
```
    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

Class Blob

Nested Class Summary

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

Method Summary

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

Methods inherited from class java.lang.Object

Method Detail

exists

content

reload

update

delete

copyTo

copyTo

copyTo

reader

writer

signUrl

storage

toBuilder

equals

hashCode