Package org.jboss.resteasy.spi

Class PriorityServiceLoader<S>

java.lang.Object

org.jboss.resteasy.spi.PriorityServiceLoader<S>

All Implemented Interfaces:

Iterable<S>

public class PriorityServiceLoader<S>
extends Object
implements Iterable<S>

A service loader which loads classes aggressively sorting the implementations by the value in the Priority annotation. If the implementation does not include the annotation Integer.MAX_VALUE is used for the priority. The instances themselves are lazily created.

Constructor

If a constructor function is used the argument passed to the function is the resolved type. The function is free to construct the type however it sees fit.

Example:

 PriorityServiceLoader.load(Service.class, (service) -> {
     try {
         return service.getConstructor(String.class).newInstance("init value");
     } catch (Exception e) {
         throw new RuntimeException(e);
     }
 });
 

Since:

6.1

Author:

James R. Perkins

See Also:

ServiceLoader

Method Summary

Modifier and Type	Method	Description
Optional<S>	first()	If there are services available the first one is returned.
Set<Class<S>>	getTypes()	Returns the types found for this service.
Iterator<S>	iterator()
Optional<S>	last()	If there are services available the last one is returned.
static <S> PriorityServiceLoader<S>	load(Class<S> type)	Creates a new service loader for the type.
static <S> PriorityServiceLoader<S>	load(Class<S> type, ClassLoader cl)	Creates a new service loader for the type and class loader.
static <S> PriorityServiceLoader<S>	load(Class<S> type, ClassLoader cl, Function<Class<? extends S>,S> constructor)	Creates a new service loader for the type and class loader.
static <S> PriorityServiceLoader<S>	load(Class<S> type, Function<Class<? extends S>,S> constructor)	Creates a new service loader for the type.
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Detail

load

public static <S> PriorityServiceLoader<S> load(Class<S> type)

Creates a new service loader for the type.

To resolve the class loader this first attempts to get the current threads context class loader. If that is null the services class loader is used. Finally if the class loader from the service is null then the system class loader is used.

Parameters:

type - the type to load the services for

Returns:

a new service loader

Throws:

SecurityException - if the security manager is enabled there is a security issue loading the class or retrieving the class loader

load

public static <S> PriorityServiceLoader<S> load(Class<S> type,
                                                Function<Class<? extends S>,S> constructor)

Creates a new service loader for the type.

To resolve the class loader this first attempts to get the current threads context class loader. If that is null the services class loader is used. Finally if the class loader from the service is null then the system class loader is used.

Parameters:

type - the type to load the services for

constructor - an optional constructor used to construct the type

Returns:

a new service loader

Throws:

SecurityException - if the security manager is enabled there is a security issue loading the class or retrieving the class loader

load

public static <S> PriorityServiceLoader<S> load(Class<S> type,
                                                ClassLoader cl)

Creates a new service loader for the type and class loader.

Parameters:

type - the type to load the services for

cl - the class loader used to load the found services

Returns:

a new service loader

Throws:

SecurityException - if the security manager is enabled and there is a security issue loading the class

load

public static <S> PriorityServiceLoader<S> load(Class<S> type,
                                                ClassLoader cl,
                                                Function<Class<? extends S>,S> constructor)

Creates a new service loader for the type and class loader.

Parameters:

type - the type to load the services for

cl - the class loader used to load the found services

constructor - an optional constructor used to construct the type

Returns:

a new service loader

Throws:

SecurityException - if the security manager is enabled and there is a security issue loading the class

first

public Optional<S> first()

If there are services available the first one is returned.

Returns:

the first service or an empty optional

Throws:

SecurityException - if the security manager is enabled and there is a security error instantiating the object

last

public Optional<S> last()

If there are services available the last one is returned.

Returns:

the last service or an empty optional

Throws:

SecurityException - if the security manager is enabled and there is a security error instantiating the object

getTypes

public Set<Class<S>> getTypes()

Returns the types found for this service.

Note if accessed before the iterator the types are not actually constructed.

Returns:

the types found for this service

iterator

public Iterator<S> iterator()

Specified by:

iterator in interface Iterable<S>

Throws:

SecurityException - if the security manager is enabled and there is a security error instantiating the object

toString

public String toString()

Overrides:

toString in class Object