Package org.apache.sis.storage

Class DataStoreRegistry

java.lang.Object

org.apache.sis.storage.DataStoreRegistry

final class DataStoreRegistry
extends Object

Creates DataStore instances for a given storage object by scanning all providers on the classpath. Storage objects are typically File or DataSource instances, but can also be any other objects documented in the StorageConnector class.

API note: this class is package-private for now in order to get more experience about what could be a good API. This class may become public in a future SIS version.

Thread safety

The same DataStoreRegistry instance can be safely used by many threads without synchronization on the part of the caller.

Since:

0.4

Version:

1.1

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static enum	DataStoreRegistry.Category	The kind of providers to test.

Field Summary

Fields

Modifier and Type	Field	Description
private final ServiceLoader<DataStoreProvider>	loader	The loader to use for searching for DataStoreProvider implementations.

Constructor Summary

Constructors

Constructor	Description
DataStoreRegistry()	Creates a new registry which will look for data stores accessible to the default class loader.
DataStoreRegistry(ClassLoader loader)	Creates a new registry which will look for data stores accessible to the given class loader.

Method Summary

Modifier and Type	Method	Description
private ProbeProviderPair	lookup(Object storage, boolean open)	Implementation of probeContentType(Object) and open(Object).
DataStore	open(Object storage)	Creates a DataStore for reading the given storage.
String	probeContentType(Object storage)	Returns the MIME type of the storage file format, or null if unknown or not applicable.
Set<DataStoreProvider>	providers()	Returns the list of data store providers available at this method invocation time.

Methods inherited from class java.lang.Object

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

Field Details

loader

private final ServiceLoader<DataStoreProvider> loader

The loader to use for searching for DataStoreProvider implementations. Note that ServiceLoader are not thread-safe - usage of this field must be protected in a synchronized block.

Constructor Details

DataStoreRegistry

public DataStoreRegistry()

Creates a new registry which will look for data stores accessible to the default class loader. The default is the current thread context class loader, provided that it can access at least the Apache SIS stores.

DataStoreRegistry

public DataStoreRegistry(ClassLoader loader)

Creates a new registry which will look for data stores accessible to the given class loader.

Parameters:

loader - the class loader to use for loading DataStoreProvider implementations.

Method Details

providers

public Set<DataStoreProvider> providers()

Returns the list of data store providers available at this method invocation time. More providers may be added later if new modules are added on the classpath.

Returns:

descriptions of available data stores.

Since:

0.8

probeContentType

public String probeContentType(Object storage)
                        throws DataStoreException

Returns the MIME type of the storage file format, or null if unknown or not applicable.

Parameters:

storage - the input/output object as a URL, file, image input stream, etc..

Returns:

the storage MIME type, or null if unknown or not applicable.

Throws:

DataStoreException - if an error occurred while opening the storage.

open

public DataStore open(Object storage)
               throws UnsupportedStorageException,
DataStoreException

Creates a DataStore for reading the given storage. The storage argument can be any of the following types:

• A Path or a File for a file or a directory.
• A URI or a URL to a distant resource.
• A CharSequence interpreted as a filename or a URL.
• A Channel, DataInput, InputStream or Reader.
• A DataSource or a Connection to a JDBC database.
• Any other DataStore-specific object, for example ucar.nc2.NetcdfFile.
• An existing StorageConnector instance.

Parameters:

storage - the input/output object as a URL, file, image input stream, etc..

Returns:

the object to use for reading geospatial data from the given storage.

Throws:

UnsupportedStorageException - if no DataStoreProvider is found for a given storage object.

DataStoreException - if an error occurred while opening the storage.

lookup

private ProbeProviderPair lookup(Object storage,
 boolean open)
                          throws DataStoreException

Implementation of probeContentType(Object) and open(Object).

Parameters:

storage - the input/output object as a URL, file, image input stream, etc..

open - true for creating a DataStore, or false if not needed.

Returns:

the result, or null if the format is not recognized and open is false.

Throws:

UnsupportedStorageException - if no DataStoreProvider is found for a given storage object.

DataStoreException - if an error occurred while opening the storage.