org.jboss.ws.api.util

Class ServiceLoader

java.lang.Object

org.jboss.ws.api.util.ServiceLoader

public final class ServiceLoader
extends java.lang.Object

Load a service class of a given name using this ordered lookup procedure:

1. If a resource file with the given name is found in META-INF/services/..., then its first line, if present, is used as the UTF-8 encoded name of the implementation class.
2. If the ${java.home}/lib/jaxws.properties file exists and it is readable by the java.util.Properties.load(InputStream) method and it contains an entry whose key is the given name, then the value of that entry is used as the name of the implementation class.
3. If a system property with the given name is defined, then its value is used as the name of the implementation class.
4. Finally, a default implementation class name is used.

Since:

14-Dec-2006

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	ServiceLoader.PropertyAccessAction
private static class	ServiceLoader.PropertyFileAccessAction
private static class	ServiceLoader.PropertyFileExistAction

Field Summary

Fields

Modifier and Type	Field and Description
private static java.util.Map<java.lang.ClassLoader,java.util.Map<java.lang.String,java.lang.String>>	serviceMap A synchronized weak hash map that keeps factory names retrieved using Service API (META-INF/services/*) for each classloader.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	ServiceLoader() Constructor.

Method Summary

Modifier and Type	Method and Description
private static java.lang.String	getServiceNameUsingCache(java.lang.ClassLoader loader, java.lang.String filename)
private static java.lang.Object	loadDefault(java.lang.String defaultFactory, java.lang.ClassLoader loader)
private static java.lang.Object	loadFromPropertiesFile(java.lang.String propertyName, java.lang.ClassLoader loader) Use the properties file "${java.home}/lib/jaxws.properties" in the JRE directory.
private static java.lang.Object	loadFromServices(java.lang.String propertyName, java.lang.ClassLoader loader) Use the Services API (as detailed in the JAR specification), if available, to determine the classname.
private static java.lang.Object	loadFromSystemProperty(java.lang.String propertyName, java.lang.String defaultFactory, java.lang.ClassLoader loader) Use the system property
static java.lang.Object	loadService(java.lang.String propertyName, java.lang.String defaultFactory) This method uses the algorithm below using the JAXWS Provider as an example.
static java.lang.Object	loadService(java.lang.String propertyName, java.lang.String defaultFactory, java.lang.ClassLoader cl) This method uses the algorithm below using the JAXWS Provider as an example.

Methods inherited from class java.lang.Object

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

Field Detail

serviceMap

private static java.util.Map<java.lang.ClassLoader,java.util.Map<java.lang.String,java.lang.String>> serviceMap

A synchronized weak hash map that keeps factory names retrieved using Service API (META-INF/services/*) for each classloader. Weak keys are used to remove entries when classloaders are garbage collected; values are service-property-name -> factory name maps.

Constructor Detail

ServiceLoader

private ServiceLoader()

Constructor.

Method Detail

loadService

public static java.lang.Object loadService(java.lang.String propertyName,
                                           java.lang.String defaultFactory,
                                           java.lang.ClassLoader cl)

This method uses the algorithm below using the JAXWS Provider as an example.

 1. If a resource with the name of META-INF/services/javax.xml.ws.spi.Provider exists, then
 its first line, if present, is used as the UTF-8 encoded name of the implementation class.
 
 2. If the ${java.home}/lib/jaxws.properties file exists and it is readable by the 
 java.util.Properties.load(InputStream) method and it contains an entry whose key is 
 javax.xml.ws.spi.Provider, then the value of that entry is used as the name of the implementation class.
 
 3. If a system property with the name javax.xml.ws.spi.Provider is defined, then its value is used
 as the name of the implementation class.
 
 4. Finally, a default implementation class name is used.
 

Parameters:

propertyName - The property name for the service to resolve

defaultFactory - Default factory class name to be used when not able to resolve anything

cl - The classLoader to be used for loading resolved service

Returns:

A new instance of the required service

loadService

public static java.lang.Object loadService(java.lang.String propertyName,
                                           java.lang.String defaultFactory)

This method uses the algorithm below using the JAXWS Provider as an example.

 1. If a resource with the name of META-INF/services/javax.xml.ws.spi.Provider exists, then
 its first line, if present, is used as the UTF-8 encoded name of the implementation class.
 
 2. If the ${java.home}/lib/jaxws.properties file exists and it is readable by the 
 java.util.Properties.load(InputStream) method and it contains an entry whose key is 
 javax.xml.ws.spi.Provider, then the value of that entry is used as the name of the implementation class.
 
 3. If a system property with the name javax.xml.ws.spi.Provider is defined, then its value is used
 as the name of the implementation class.
 
 4. Finally, a default implementation class name is used.
 

This is equivalent to calling loadService(String propertyName, String defaultFactory, ClassLoader cl) passing in the Thread.currentThread().getContextClassLoader().

Parameters:

propertyName - The property name for the service to resolve

defaultFactory - Default factory class name to be used when not able to resolve anything

Returns:

A new instance of the required service

loadFromServices

private static java.lang.Object loadFromServices(java.lang.String propertyName,
                                                 java.lang.ClassLoader loader)

Use the Services API (as detailed in the JAR specification), if available, to determine the classname.

getServiceNameUsingCache

private static java.lang.String getServiceNameUsingCache(java.lang.ClassLoader loader,
                                                         java.lang.String filename)
                                                  throws java.io.IOException

Throws:

java.io.IOException

loadFromSystemProperty

private static java.lang.Object loadFromSystemProperty(java.lang.String propertyName,
                                                       java.lang.String defaultFactory,
                                                       java.lang.ClassLoader loader)

Use the system property

loadFromPropertiesFile

private static java.lang.Object loadFromPropertiesFile(java.lang.String propertyName,
                                                       java.lang.ClassLoader loader)

Use the properties file "${java.home}/lib/jaxws.properties" in the JRE directory. This configuration file is in standard java.util.Properties format and contains the fully qualified name of the implementation class with the key being the system property defined above.

loadDefault

private static java.lang.Object loadDefault(java.lang.String defaultFactory,
                                            java.lang.ClassLoader loader)