org.springframework.core.io.support

Class SpringFactoriesLoader

java.lang.Object

org.springframework.core.io.support.SpringFactoriesLoader

public final class SpringFactoriesLoader
extends Object

General purpose factory loading mechanism for internal use within the framework.

SpringFactoriesLoader loads and instantiates factories of a given type from "META-INF/spring.factories" files which may be present in multiple JAR files in the classpath. The spring.factories file must be in Properties format, where the key is the fully qualified name of the interface or abstract class, and the value is a comma-separated list of implementation class names. For example:

example.MyService=example.MyServiceImpl1,example.MyServiceImpl2

where example.MyService is the name of the interface, and MyServiceImpl1 and MyServiceImpl2 are two implementations.

Since:

3.2

Author:

Arjen Poutsma, Juergen Hoeller, Sam Brannen

Field Summary

Fields

Modifier and Type	Field and Description
static String	FACTORIES_RESOURCE_LOCATION The location to look for factories.

Method Summary

Modifier and Type	Method and Description
static <T> List<T>	loadFactories(Class<T> factoryType, ClassLoader classLoader) Load and instantiate the factory implementations of the given type from "META-INF/spring.factories", using the given class loader.
static List<String>	loadFactoryNames(Class<?> factoryType, ClassLoader classLoader) Load the fully qualified class names of factory implementations of the given type from "META-INF/spring.factories", using the given class loader.

Methods inherited from class java.lang.Object

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

Field Detail

FACTORIES_RESOURCE_LOCATION

public static final String FACTORIES_RESOURCE_LOCATION

The location to look for factories.

Can be present in multiple JAR files.

See Also:

Constant Field Values

Method Detail

loadFactories

public static <T> List<T> loadFactories(Class<T> factoryType,
                                        @Nullable
                                        ClassLoader classLoader)

Load and instantiate the factory implementations of the given type from "META-INF/spring.factories", using the given class loader.

The returned factories are sorted through AnnotationAwareOrderComparator.

If a custom instantiation strategy is required, use loadFactoryNames(java.lang.Class<?>, java.lang.ClassLoader) to obtain all registered factory names.

As of Spring Framework 5.3, if duplicate implementation class names are discovered for a given factory type, only one instance of the duplicated implementation type will be instantiated.

Parameters:

factoryType - the interface or abstract class representing the factory

classLoader - the ClassLoader to use for loading (can be null to use the default)

Throws:

IllegalArgumentException - if any factory implementation class cannot be loaded or if an error occurs while instantiating any factory

See Also:

loadFactoryNames(java.lang.Class<?>, java.lang.ClassLoader)

loadFactoryNames

public static List<String> loadFactoryNames(Class<?> factoryType,
                                            @Nullable
                                            ClassLoader classLoader)

Load the fully qualified class names of factory implementations of the given type from "META-INF/spring.factories", using the given class loader.

As of Spring Framework 5.3, if a particular implementation class name is discovered more than once for the given factory type, duplicates will be ignored.

Parameters:

factoryType - the interface or abstract class representing the factory

classLoader - the ClassLoader to use for loading resources; can be null to use the default

Throws:

IllegalArgumentException - if an error occurs while loading factory names

See Also:

loadFactories(java.lang.Class<T>, java.lang.ClassLoader)