net.time4j.base

Class ResourceLoader

java.lang.Object

net.time4j.base.ResourceLoader

public abstract class ResourceLoader
extends Object

Defines a general access point of loading any text resources and services.

Specification: All external subclasses must have a public no-arg constructor.

Since:

3.5/4.3

Author:

Meno Hochschild

Field Summary

Fields

Modifier and Type	Field and Description
static String	EXTERNAL_RESOURCE_LOADER Name of system property responsible for getting an external instance as fully qualified class name.
static String	USE_OF_CLASSLOADER_ONLY Name of system property controlling if the use of classloader should be enforced instead of trying an URI-construction first.

Method Summary

Modifier and Type	Method and Description
static ResourceLoader	getInstance() Applications should never use the constructor but this static method to achieve a general instance.
InputStream	load(Class<?> moduleRef, String path, boolean noCache) Loads a resource as input stream based on the classloader of given module reference.
abstract InputStream	load(URI uri, boolean noCache) Loads given URI-resource as input stream.
abstract URI	locate(String moduleName, Class<?> moduleRef, String path) Constructs an URI for given module resource.
<S> void	registerService(Class<S> serviceInterface, S implementation) Registers an external service provider.
abstract <S> Iterable<S>	services(Class<S> serviceInterface) Finds a collection of service providers available for given service provider interface.

Methods inherited from class java.lang.Object

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

Field Detail

EXTERNAL_RESOURCE_LOADER

public static final String EXTERNAL_RESOURCE_LOADER

Name of system property responsible for getting an external instance as fully qualified class name.

Time4J will throw an Error if the configuration entry is wrong.

See Also:

Constant Field Values

USE_OF_CLASSLOADER_ONLY

public static final String USE_OF_CLASSLOADER_ONLY

Name of system property controlling if the use of classloader should be enforced instead of trying an URI-construction first.

The value is either "true" or "false" (default). This property will be ignored on Android platforms. Applications in an OSGi-environment should set the property value to true.

Since:

3.16/4.13

See Also:

Constant Field Values

Method Detail

getInstance

public static ResourceLoader getInstance()

Applications should never use the constructor but this static method to achieve a general instance.

Returns:

ResourceLoader

Since:

3.5/4.3

locate

public abstract URI locate(String moduleName,
                           Class<?> moduleRef,
                           String path)

Constructs an URI for given module resource.

Attention: Some implementations might yield an uri without verifying if the uri resource really exists.

Parameters:

moduleName - name of related time4j-module

moduleRef - module-specific class reference

path - path to text resource

Returns:

uri of resource or null if unable to locate the resource

Since:

3.5/4.3

load

public abstract InputStream load(URI uri,
                                 boolean noCache)

Loads given URI-resource as input stream.

Callers are responsible for closing the result stream.

Parameters:

uri - uniform resource identifier as result of locate-method (optional)

noCache - avoid caching?

Returns:

input stream or null if the resource could not be opened

Since:

3.5/4.3

See Also:

locate(String, Class, String)

load

public final InputStream load(Class<?> moduleRef,
                              String path,
                              boolean noCache)
                       throws IOException

Loads a resource as input stream based on the classloader of given module reference.

Callers are responsible for closing the result stream.

Parameters:

moduleRef - module-specific class reference

path - path to text resource (must be understandable by class loaders)

noCache - avoid caching?

Returns:

input stream

Throws:

IOException - if the stream cannot be opened or if this method is called on Android platforms

Since:

3.16/4.13

services

public abstract <S> Iterable<S> services(Class<S> serviceInterface)

Finds a collection of service providers available for given service provider interface.

Type Parameters:

S - generic service type

Parameters:

serviceInterface - service provider interface

Returns:

iterable collection of service providers

Since:

3.5/4.3

registerService

public <S> void registerService(Class<S> serviceInterface,
                                S implementation)

Registers an external service provider.

This method is mainly intended to register an extra time zone repository in the context of OSGi where the service loader mechanism does not work. Important: Calling this method must be done before executing any other Time4J-code. Example for registering the tzdata-module (v3.0 or later):

     ResourceLoader.getInstance().registerService(
       ZoneModelProvider.class,
       new net.time4j.tz.repo.TimezoneRepositoryProviderSPI());
 

Note: The example can be shortened by the expression net.time4j.tz.repo.TZDATA.init() which also provides actual leap second support.

Type Parameters:

S - generic service type

Parameters:

serviceInterface - service interface

implementation - service provider

Throws:

IllegalStateException - if already registered or called on a non-standard resource loader like on Android

Since:

5.0