Module org.tentackle.common

Package org.tentackle.common

Class DefaultServiceFinder

java.lang.Object

org.tentackle.common.DefaultServiceFinder

All Implemented Interfaces:

ServiceFinder

public class DefaultServiceFinder
extends Object
implements ServiceFinder

Default implementation of a ServiceFinder.

Author:

harald

Constructor Summary

Constructors

Constructor	Description
DefaultServiceFinder()	Creates a default service finder. The classloader used is Thread.currentThread().getContextClassLoader(). The servicepath is "META_INF/services/".
DefaultServiceFinder(ClassLoader loader, String servicePath)	Creates a service finder.
DefaultServiceFinder(String servicePath)	Creates a default service finder. The classloader used is Thread.currentThread().getContextClassLoader().

Method Summary

Modifier and Type	Method	Description
Map<String,String>	createNameMap(String serviceName)	Creates a map of classnames to mapped services.
Map<String,Set<String>>	createNameMapToAll(String serviceName)	Creates a map of names to all mapped services.
Map.Entry<String,URL>	findFirstServiceConfiguration(String serviceName)	Finds the first service configurations by service name. If similar configurations appear more than once on the classpath, the first is returned.
<T> Class<T>	findFirstServiceProvider(Class<T> service)	Finds the first service provider by service name. If similar configurations appear more than once on the classpath, the first is returned.
Map<String,URL>	findServiceConfigurations(String serviceName)	Finds service configurations by service name. Iterations over the returned map are ordered by discovery along the classpath.
<T> Collection<Class<T>>	findServiceProviders(Class<T> service)	Finds the service providers by service names.
Collection<URL>	findServiceURLs(String serviceName)	Finds URLs of a service by name.
Map.Entry<String,URL>	findUniqueServiceConfiguration(String serviceName)	Finds a unique service configurations by service name. It is checked that the service is defined exactly once.
<T> Class<T>	findUniqueServiceProvider(Class<T> service)	Finds the unique service provider by service class.
ClassLoader	getClassLoader()	Gets the classloader used by this finder.
protected ClassLoader	getClassLoader(String serviceName)	Gets the classloader for the given service name.
String	getServicePath()	Gets the finder' service path it is responsible for.
protected String	normalizeLine(String line)	Normalizes a line. Trailing and leading spaces are ignored.
protected void	parseURL(URL url, String serviceName, Map<String,URL> services)	Parses a service URL. The implementation assumes the provider configuration file in property-file format.
protected void	parseURLs(Collection<URL> urls, String serviceName, Map<String,URL> services)	Parses an enumeration of URLs.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultServiceFinder

public DefaultServiceFinder(ClassLoader loader,
                            String servicePath)

Creates a service finder.

Parameters:

loader - optional classloader, null if use ClassLoader.getSystemClassLoader()

servicePath - optional service path prefix, null if "META_INF/services/"

DefaultServiceFinder

public DefaultServiceFinder(String servicePath)

Creates a default service finder.
The classloader used is Thread.currentThread().getContextClassLoader().

Parameters:

servicePath - optional service path prefix, null if "META_INF/services/"

DefaultServiceFinder

public DefaultServiceFinder()

Creates a default service finder.
The classloader used is Thread.currentThread().getContextClassLoader().
The servicepath is "META_INF/services/".

Method Detail

getClassLoader

public ClassLoader getClassLoader()

Gets the classloader used by this finder.

Specified by:

getClassLoader in interface ServiceFinder

Returns:

the classloader, never null

getServicePath

public String getServicePath()

Gets the finder' service path it is responsible for.

Specified by:

getServicePath in interface ServiceFinder

Returns:

the service path

findServiceURLs

public Collection<URL> findServiceURLs(String serviceName)

Finds URLs of a service by name.

Specified by:

findServiceURLs in interface ServiceFinder

Parameters:

serviceName - the service name, usually a classname

Returns:

the service's resource urls

findServiceConfigurations

public Map<String,URL> findServiceConfigurations(String serviceName)

Finds service configurations by service name.
Iterations over the returned map are ordered by discovery along the classpath.

Specified by:

findServiceConfigurations in interface ServiceFinder

Parameters:

serviceName - the service name, usually a classname

Returns:

a map of the configured services and their corresponding URLs

findFirstServiceConfiguration

public Map.Entry<String,URL> findFirstServiceConfiguration(String serviceName)

Finds the first service configurations by service name.
If similar configurations appear more than once on the classpath, the first is returned. Useful to override service default implementations.

Specified by:

findFirstServiceConfiguration in interface ServiceFinder

Parameters:

serviceName - the service name, usually a classname

Returns:

the service configuation entry

findUniqueServiceConfiguration

public Map.Entry<String,URL> findUniqueServiceConfiguration(String serviceName)

Finds a unique service configurations by service name.
It is checked that the service is defined exactly once. Useful for factories, singletons and alike.

Specified by:

findUniqueServiceConfiguration in interface ServiceFinder

Parameters:

serviceName - the service name, usually a classname

Returns:

the service configuation entry

findServiceProviders

public <T> Collection<Class<T>> findServiceProviders(Class<T> service)
                                              throws ClassNotFoundException

Finds the service providers by service names.

Specified by:

findServiceProviders in interface ServiceFinder

Type Parameters:

T - the service type

Parameters:

service - the service class

Returns:

the classes providing this service

Throws:

ClassNotFoundException - if some provider could not be loaded

findFirstServiceProvider

public <T> Class<T> findFirstServiceProvider(Class<T> service)
                                      throws ClassNotFoundException

Finds the first service provider by service name.
If similar configurations appear more than once on the classpath, the first is returned. Useful to override service default implementations.

Specified by:

findFirstServiceProvider in interface ServiceFinder

Type Parameters:

T - the service type

Parameters:

service - the service class

Returns:

the provider class

Throws:

ClassNotFoundException - if some provider could not be loaded

findUniqueServiceProvider

public <T> Class<T> findUniqueServiceProvider(Class<T> service)
                                       throws ClassNotFoundException

Finds the unique service provider by service class.

Specified by:

findUniqueServiceProvider in interface ServiceFinder

Type Parameters:

T - the service type

Parameters:

service - the service class

Returns:

the provider class

Throws:

ClassNotFoundException - if some provider could not be loaded

createNameMap

public Map<String,String> createNameMap(String serviceName)

Creates a map of classnames to mapped services.

They key of the map is the service name. The value is the name providing the service which comes first in the classpath.

Specified by:

createNameMap in interface ServiceFinder

Parameters:

serviceName - the service class

Returns:

the map

createNameMapToAll

public Map<String,Set<String>> createNameMapToAll(String serviceName)

Creates a map of names to all mapped services.

They key of the map is the service name. The value is a list of names providing the service ordered by discovery along the classpath.

Specified by:

createNameMapToAll in interface ServiceFinder

Parameters:

serviceName - the service class

Returns:

the map

getClassLoader

protected ClassLoader getClassLoader(String serviceName)

Gets the classloader for the given service name.

Parameters:

serviceName - the service name

Returns:

the loader, never null

parseURL

protected void parseURL(URL url,
                        String serviceName,
                        Map<String,URL> services)

Parses a service URL.
The implementation assumes the provider configuration file in property-file format. This includes the special case of key-only properties which is equivalent to the format used in ServiceLoader.

Parameters:

url - the url of the provider definition

serviceName - the name of the service

services - the implementing services map

parseURLs

protected void parseURLs(Collection<URL> urls,
                         String serviceName,
                         Map<String,URL> services)

Parses an enumeration of URLs.

Parameters:

urls - the URLs

serviceName - the service name

services - the destination map

normalizeLine

protected String normalizeLine(String line)

Normalizes a line.
Trailing and leading spaces are ignored. Comments starting with a hash # are stripped. A hash can be escaped by a backslash.

Parameters:

line - the source line

Returns:

the normalized line, null if line contains no information