- All Implemented Interfaces:
Serializable
DataStore in read and/or write mode.
StorageConnector wraps an input Object, which can be any of the following types:
- A
Pathor aFilefor a file or a directory. - A
URIor aURLto a distant resource. - A
CharSequenceinterpreted as a filename or a URL. - A
Channel,DataInput,InputStreamorReader. - A
DataSourceor aConnectionto a JDBC database. - Any other
DataStore-specific object, for exampleNetcdfFile.
getStorageAs(Class) method provides the storage as an object of the given type, opening
the input stream if necessary. This class tries to open the stream only once - subsequent invocation
of getStorageAs(…) may return the same input stream.
This class is used only for discovery of a DataStore implementation capable to handle the input.
Once a suitable DataStore has been found, the StorageConnector instance is typically
discarded since each data store implementation will use their own input/output objects.
Limitations
This class is not thread-safe. Not onlyStorageConnector should be used by a single thread,
but the objects returned by getStorageAs(Class) should also be used by the same thread.
Instances of this class are serializable if the storage object given at construction time
is serializable.
- Since:
- 0.3
- See Also:
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final intThe default size (in bytes) ofByteBuffers created by storage connectors. -
Constructor Summary
ConstructorsConstructorDescriptionStorageConnector(Object storage) Creates a new data store connection wrapping the given input/output object. -
Method Summary
Modifier and TypeMethodDescriptionvoidcloseAllExcept(Object view) Closes all streams and connections created by thisStorageConnectorexcept the given view.<S> SReturns the storage as a view of the given type and closes all other views.Returns the filename extension of the input/output object.<T> TgetOption(OptionKey<T> key) Returns the option value for the given key, ornullif none.Returns the input/output object given at construction time.<S> SgetStorageAs(Class<S> type) Returns the storage as a view of the given type if possible, ornullotherwise.Returns a short name of the input/output object.<T> voidsetOption(OptionKey<T> key, T value) Sets the option value for the given key.Returns a string representation of thisStorageConnectorfor debugging purpose.booleanReturns whether returning the storage would have required the creation of a new file.
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Field Details
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DEFAULT_BUFFER_SIZE
public static final int DEFAULT_BUFFER_SIZEThe default size (in bytes) ofByteBuffers created by storage connectors. Those buffers are typically created when the specified storage object is aFile,Path,URLorURI. The default buffer size is arbitrary and may change in any future Apache SIS version.Users can override this value by providing a value for
OptionKey.BYTE_BUFFER.- Since:
- 1.4
- See Also:
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Constructor Details
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StorageConnector
Creates a new data store connection wrapping the given input/output object. The object can be of any type, but the class javadoc lists the most typical ones.- Parameters:
storage- the input/output object as a URL, file, image input stream, etc..
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Method Details
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getOption
Returns the option value for the given key, ornullif none.- Type Parameters:
T- the type of option value.- Parameters:
key- the option for which to get the value.- Returns:
- the current value for the given option, or
nullif none.
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setOption
Sets the option value for the given key. The default implementation recognizes the following options:OptionKey.ENCODINGfor decoding characters in an input stream, if needed.OptionKey.URL_ENCODINGfor converting URL to URI or filename, if needed.OptionKey.OPEN_OPTIONSfor specifying whether the data store shall be read only or read/write.OptionKey.BYTE_BUFFERfor allowing users to control the byte buffer to be created.
- Type Parameters:
T- the type of option value.- Parameters:
key- the option for which to set the value.value- the new value for the given option, ornullfor removing the value.
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getStorage
Returns the input/output object given at construction time. The object can be of any type, but the class javadoc lists the most typical ones.- Returns:
- the input/output object as a URL, file, image input stream, etc..
- Throws:
DataStoreException- if the storage object has already been used and cannot be reused.- See Also:
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getStorageName
Returns a short name of the input/output object. For example if the storage is a file, this method returns the filename without the path (but including the file extension). The default implementation performs the following choices based on the type of the storage object:- For
Path,File,URIorURLinstances, this method uses dedicated API likePath.getFileName(). - For
CharSequenceinstances, this method gets a string representation of the storage object and returns the part after the last'/'character or platform-dependent name separator. - For instances of unknown type, this method builds a string representation using the class name. Note that the string representation of unknown types may change in any future SIS version.
- Returns:
- a short name of the storage object.
- For
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getFileExtension
Returns the filename extension of the input/output object. The default implementation performs the following choices based on the type of the storage object:- For
Path,File,URI,URLorCharSequenceinstances, this method returns the string after the last'.'character in the filename, provided that the'.'is not the first filename character. This may be an empty string if the filename has no extension, but nevernull. - For instances of unknown type, this method returns
null.
- Returns:
- the filename extension, or an empty string if none,
or
nullif the storage is an object of unknown type.
- For
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getStorageAs
Returns the storage as a view of the given type if possible, ornullotherwise. The default implementation accepts the following types:String:Path,URI,URL,File:ByteBuffer:- If the storage object can be obtained as described in bullet 2 of the
DataInputsection below, then this method returns the associated byte buffer. - Otherwise this method returns
null.
- If the storage object can be obtained as described in bullet 2 of the
DataInput:- If the storage object is already an instance of
DataInput(including theImageInputStreamandImageOutputStreamtypes), then it is returned unchanged. - Otherwise if the input is an instance of
ByteBuffer, then anImageInputStreambacked by a read-only view of that buffer is created when first needed and returned. The properties (position, mark, limit) of the original buffer are unmodified. - Otherwise if the input is an instance of
Path,File,URI,URL,CharSequence,InputStreamorReadableByteChannel, then anImageInputStreambacked by aByteBufferis created when first needed and returned. - Otherwise if
ImageIO.createImageInputStream(Object)returns a non-null value, then this value is cached and returned. - Otherwise this method returns
null.
- If the storage object is already an instance of
ImageInputStream:- If the above
DataInputcan be created and casted toImageInputStream, returns it. - Otherwise this method returns
null.
- If the above
InputStream:- If the storage object is already an instance of
InputStream, then it is returned unchanged. - Otherwise if the above
ImageInputStreamcan be created, returns a wrapper around that stream. - Otherwise this method returns
null.
- If the storage object is already an instance of
Reader:- If the storage object is already an instance of
Reader, then it is returned unchanged. - Otherwise if the above
InputStreamcan be created, returns anInputStreamReaderusing the encoding specified byOptionKey.ENCODINGif any, or using the system default encoding otherwise. - Otherwise this method returns
null.
- If the storage object is already an instance of
Connection:- If the storage object is already an instance of
Connection, then it is returned unchanged. - Otherwise if the storage is an instance of
DataSource, then a connection is obtained when first needed and returned. - Otherwise this method returns
null.
- If the storage object is already an instance of
- Any other types:
- If the storage given at construction time is already an instance of the requested type, returns it as-is.
- Otherwise this method throws
IllegalArgumentException.
Usage for probing operations
Multiple invocations of this method on the sameStorageConnectorinstance will try to return the same instance on a best effort basis. Consequently, implementations ofDataStoreProvider.probeContent(StorageConnector)methods shall not close the stream or database connection returned by this method. In addition, thoseprobeContent(StorageConnector)methods are responsible for restoring the stream or byte buffer to its original position on return. For an easier and safer way to ensure that the storage position is not modified, seeDataStoreProvider.probeContent(StorageConnector, Class, Prober).- Type Parameters:
S- the compile-time type of thetypeargument (the source or storage type).- Parameters:
type- the desired type as one ofByteBuffer,DataInput,Connectionclass or other types supported byStorageConnectorsubclasses.- Returns:
- the storage as a view of the given type, or
nullif the given type is one of the supported types listed in javadoc but no view can be created for the source given at construction time. In the latter case,wasProbingAbsentFile()can be invoked for determining whether the reason is that the file does not exist but could be created. - Throws:
IllegalArgumentException- if the giventypeargument is not one of the supported types listed in this javadoc or in subclass javadoc.IllegalStateException- if thisStorageConnectorhas been closed.DataStoreException- if an error occurred while opening a stream or database connection.- See Also:
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wasProbingAbsentFile
public boolean wasProbingAbsentFile()Returns whether returning the storage would have required the creation of a new file. This method may returntrueif all the following conditions are true:- A previous
getStorageAs(Class)call requested some kind of input stream (e.g.InputStream,ImageInputStream,DataInput,Reader). - The storage is an object convertible to a
Pathand the file identified by that path does not exist. - The optons given to this
StorageConnectorincludeStandardOpenOption.CREATEorCREATE_NEW. - The
getStorageAs(…)andwasProbingAbsentFile()calls happened in the context ofDataStoresprobing the storage content in order to choose aDataStoreProvider.
getStorageAs(Class)returnsnullinstead of creating a new empty file. In such case,DataStoreProvidermay use thiswasProbingAbsentFile()method for deciding whether to reportProbeResult.SUPPORTEDorProbeResult.UNSUPPORTED_STORAGE.Rational
When the file does not exist and theCREATEorCREATE_NEWoption is provided,getStorageAs(…)would normally create a new empty file. However this behavior is modified during probing (the first condition in above list) because newly created files are empty and probing empty files may result inEOFExceptionto be thrown or in providers declaring that they do not support the storage.IF the
CREATEorCREATE_NEWoptions were not provided, then probing the storage content of an absent file will rather throwNoSuchFileExceptionorFileNotFoundException. So this method is useful only forDataStorehaving write capabilities.- Returns:
- whether returning the storage would have required the creation of a new file.
- Since:
- 1.4
- A previous
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commit
public <S> S commit(Class<S> type, String format) throws IllegalArgumentException, DataStoreException Returns the storage as a view of the given type and closes all other views. Invoking this method is equivalent to invokinggetStorageAs(Class)followed bycloseAllExcept(Object)except that the latter method is always invoked (in a way similar to "try with resource") and that this method never returnsnull.- Type Parameters:
S- the compile-time type of thetypeargument (the source or storage type).- Parameters:
type- the desired type as one of the types documented ingetStorageAs(Class)(example:ByteBuffer,DataInput,Connection).format- short name or abbreviation of the data format (e.g. "CSV", "GML", "WKT", etc). Used for information purpose in error messages if needed.- Returns:
- the storage as a view of the given type. Never
null. - Throws:
IllegalArgumentException- if the giventypeargument is not one of the supported types.IllegalStateException- if thisStorageConnectorhas been closed.DataStoreException- if an error occurred while opening a stream or database connection.- Since:
- 1.2
- See Also:
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closeAllExcept
Closes all streams and connections created by thisStorageConnectorexcept the given view. This method closes all objects created by thegetStorageAs(Class)method except the givenview. Ifviewisnull, then this method closes everything including the storage if it is closeable.This method is invoked when a suitable
DataStorehas been found - in which case the view used by the data store is given in argument to this method - or when no suitableDataStorehas been found - in which case theviewargument is null.This
StorageConnectorinstance shall not be used anymore after invocation of this method.- Parameters:
view- the view to leave open, ornullif none.- Throws:
DataStoreException- if an error occurred while closing the stream or database connection.- See Also:
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toString
Returns a string representation of thisStorageConnectorfor debugging purpose. This string representation is for diagnostic and may change in any future version.
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