javax.enterprise.util.TypeLiteral Maven / Gradle / Ivy
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* Copyright 2010, Red Hat, Inc., and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.enterprise.util;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
/**
*
* Supports inline instantiation of objects that represent parameterized types with actual type parameters.
*
*
*
* An object that represents any parameterized type may be obtained by subclassing TypeLiteral.
*
*
*
* TypeLiteral<List<String>> stringListType = new TypeLiteral<List<String>>() {
* };
*
*
* @author Gavin King
* @author Pete Muir
*
* @param the type, including all actual type parameters
*
* @see javax.enterprise.inject.Instance#select(TypeLiteral, Annotation...)
* @see javax.enterprise.event.Event#select(TypeLiteral, Annotation...)
*
*/
public abstract class TypeLiteral implements Serializable {
private static final long serialVersionUID = 1L;
private transient Type actualType;
protected TypeLiteral() {
}
/**
* @return the actual type represented by this object
*/
public final Type getType() {
if (actualType == null) {
Class typeLiteralSubclass = getTypeLiteralSubclass(this.getClass());
if (typeLiteralSubclass == null) {
throw new RuntimeException(getClass() + " is not a subclass of TypeLiteral");
}
actualType = getTypeParameter(typeLiteralSubclass);
if (actualType == null) {
throw new RuntimeException(getClass() + " does not specify the type parameter T of TypeLiteral");
}
}
return actualType;
}
/**
* @return the raw type represented by this object
*/
@SuppressWarnings("unchecked")
public final Class getRawType() {
Type type = getType();
if (type instanceof Class) {
return (Class) type;
} else if (type instanceof ParameterizedType) {
return (Class) ((ParameterizedType) type).getRawType();
} else if (type instanceof GenericArrayType) {
return (Class) Object[].class;
} else {
throw new RuntimeException("Illegal type");
}
}
private static Class getTypeLiteralSubclass(Class clazz) {
Class superclass = clazz.getSuperclass();
if (superclass.equals(TypeLiteral.class)) {
return clazz;
} else if (superclass.equals(Object.class)) {
return null;
} else {
return (getTypeLiteralSubclass(superclass));
}
}
private static Type getTypeParameter(Class superclass) {
Type type = superclass.getGenericSuperclass();
if (type instanceof ParameterizedType) {
ParameterizedType parameterizedType = (ParameterizedType) type;
if (parameterizedType.getActualTypeArguments().length == 1) {
return parameterizedType.getActualTypeArguments()[0];
}
}
return null;
}
@Override
public boolean equals(Object obj) {
if (obj instanceof TypeLiteral) {
TypeLiteral that = (TypeLiteral) obj;
return this.getType().equals(that.getType());
}
return false;
}
@Override
public int hashCode() {
return getType().hashCode();
}
@Override
public String toString() {
return getType().toString();
}
}