org.neo4j.helpers

Class Service

java.lang.Object

org.neo4j.helpers.Service

Direct Known Subclasses:

Service.CaseInsensitiveService

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

Nested Classes

Modifier and Type	Class and Description
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]).

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
Iterable<String>	getKeys()
int	hashCode()
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.
static <T extends Service> T	loadSilently(Class<T> type, String key) Load the Service implementation with the specified key.
boolean	matches(String key)
String	toString()

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

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

loadSilently

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

Load the Service implementation with the specified key. This method will return null if requested service not found.

Type Parameters:

T - the type of the Service to load

Parameters:

type - the type of the Service to load

key - the key that identifies the desired implementation

Returns:

requested service

load

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

Load the Service implementation with the specified key. This method should never return null.

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

matches

public boolean matches(String key)

getKeys

public Iterable<String> getKeys()

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object