com.hedera.fullstack.service.locator.api.ServiceSupplier Maven / Gradle / Ivy
/*
* Copyright (C) 2023 Hedera Hashgraph, LLC
*
* 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 com.hedera.fullstack.service.locator.api;
import com.hedera.fullstack.base.api.reflect.ClassConstructionException;
import com.hedera.fullstack.base.api.reflect.Construction;
import java.util.Objects;
/**
* The service supplier pattern is designed to decouple the service detection logic from the instantiation of the actual
* service. This allows for the service detection logic to be in compliance with the Java ServiceLoader specification
* while allowing actual service instances to be instantiated with a constructor that takes zero or more arguments.
*
* @param the type of the service.
*/
public final class ServiceSupplier {
/**
* The construction helper for the service.
*/
private final Construction construction;
/**
* Constructs a new ServiceSupplier for the given service implementation.
*
* @param type the type of the service implementation.
* @throws NullPointerException if serviceClass is null.
* @throws IllegalArgumentException if serviceClass is an interface, an abstract class, an array class, or
* has no accessible constructors.
*/
public ServiceSupplier(final Class type) {
Objects.requireNonNull(type, "type must not be null");
this.construction = Construction.of(type);
}
/**
* @return the type of the service implementation.
*/
public Class type() {
return construction.type();
}
/**
* Constructs a new instance of the service implementation using the zero argument constructor.
*
* @return a new instance of the service declared by this ServiceSupplier.
* @throws ClassConstructionException if the service cannot be constructed or instantiated.
*/
public S get() {
return construction.newInstance();
}
/**
* Constructs a new instance of the service implementation and casts the result to the specified type.
*
* @param the subclass or sub-interface to cast the service implement.
* @param args the arguments to pass to the service constructor.
* @return a new instance of the service declared by this ServiceSupplier.
* @throws ClassConstructionException if the service cannot be constructed or instantiated.
* @throws ClassCastException if the service cannot be cast to the specified type.
*/
@SuppressWarnings("unchecked")
public T cast(final Object... args) {
return (T) newServiceInstance(args);
}
/**
* Constructs a new instance of the service implementation.
*
* @param args the arguments to pass to the service constructor.
* @return a new instance of the service declared by this ServiceSupplier.
* @throws ClassConstructionException if the service cannot be constructed or instantiated.
*/
public S newServiceInstance(final Object... args) {
return construction.newInstance(args);
}
}