org.neo4j.helpers
Class Service

java.lang.Object
  org.neo4j.helpers.Service

Direct Known Subclasses:

IndexProvider, KernelExtension, Service.CaseInsensitiveService, Version

public abstract class Service
extends Object

A utility for locating services. This implements the same functionality as the Java 6 ServiceLoader interface, in fact it uses the ServiceLoader if available, but backports the functionality to previous Java versions and adds some error handling to ignore misconfigured service implementations. Additionally this class can be used as a base class for implementing services that are differentiated by a String key. An example implementation might be:

 
 public abstract class StringConverter extends org.neo4j.commons.Service
 {
     protected StringConverter(String id)
     {
         super( id );
     }

     public abstract String convert( String input );

     public static StringConverter load( String id )
     {
         return org.neo4j.commons.Service.load( StringConverter.class, id );
     }
 }
 
 

With for example these implementations:

 
 public final class UppercaseConverter extends StringConverter
 {
     public UppercaseConverter()
     {
         super( "uppercase" );
     }

     public String convert( String input )
     {
         return input.toUpperCase();
     }
 }

 public final class ReverseConverter extends StringConverter
 {
     public ReverseConverter()
     {
         super( "reverse" );
     }

     public String convert( String input )
     {
         char[] chars = input.toCharArray();
         for ( int i = 0; i < chars.length/2; i++ )
         {
             char intermediate = chars[i];
             chars[i] = chars[chars.length-1-i];
             chars[chars.length-1-i] = chars[i];
         }
         return new String( chars );
     }
 }
 
 

This would then be used as:

 
 String atad = StringConverter.load( "reverse" ).convert( "data" );
 
 

Author:

Tobias Ivarsson

Nested Class Summary

static class	Service.CaseInsensitiveService A base class for services, similar to Service, that compares keys using case insensitive comparison instead of exact comparison.
static interface	Service.Implementation Designates that a class implements the specified service and should be added to the services listings file (META-INF/services/[service-name]).

Constructor Summary

protected

Service(String key, String... altKeys) Create a new instance of a service implementation identified with the specified key(s).

Method Summary

static <T> Iterable<T>	load(Class<T> type) Load all implementations of a Service.
static <T extends Service> T	load(Class<T> type, String key) Load the Service implementation with the specified key.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

Service

protected Service(String key,
                  String... altKeys)

Create a new instance of a service implementation identified with the specified key(s).

Parameters:

key - the main key for identifying this service implementation

altKeys - alternative spellings of the identifier of this service implementation

Method Detail

load

public static <T> Iterable<T> load(Class<T> type)

Load all implementations of a Service.

Type Parameters:

T - the type of the Service

Parameters:

type - the type of the Service to load

Returns:

all registered implementations of the Service

load

public static <T extends Service> T load(Class<T> type,
                                         String key)

Load the Service implementation with the specified key.

Type Parameters:

T - the type of the Service

Parameters:

type - the type of the Service to load

key - the key that identifies the desired implementation

Returns:

the matching Service implementation

toString

public String toString()

Overrides:

toString in class Object