/*
|
* Copyright (c) 2018-2028, DreamLu All rights reserved.
|
*
|
* Redistribution and use in source and binary forms, with or without
|
* modification, are permitted provided that the following conditions are met:
|
*
|
* Redistributions of source code must retain the above copyright notice,
|
* this list of conditions and the following disclaimer.
|
* Redistributions in binary form must reproduce the above copyright
|
* notice, this list of conditions and the following disclaimer in the
|
* documentation and/or other materials provided with the distribution.
|
* Neither the name of the dreamlu.net developer nor the names of its
|
* contributors may be used to endorse or promote products derived from
|
* this software without specific prior written permission.
|
* Author: DreamLu 卢春梦 (596392912@qq.com)
|
*/
|
package org.springblade.core.tool.utils;
|
|
import org.springframework.lang.Nullable;
|
|
import java.io.Serializable;
|
import java.util.function.Supplier;
|
|
/**
|
* Holder of a value that is computed lazy.
|
*
|
* @author L.cm
|
*/
|
public class Lazy<T> implements Supplier<T>, Serializable {
|
|
@Nullable
|
private transient volatile Supplier<? extends T> supplier;
|
@Nullable
|
private T value;
|
|
/**
|
* Creates new instance of Lazy.
|
*
|
* @param supplier Supplier
|
* @param <T> 泛型标记
|
* @return Lazy
|
*/
|
public static <T> Lazy<T> of(final Supplier<T> supplier) {
|
return new Lazy<>(supplier);
|
}
|
|
private Lazy(final Supplier<T> supplier) {
|
this.supplier = supplier;
|
}
|
|
/**
|
* Returns the value. Value will be computed on first call.
|
*
|
* @return lazy value
|
*/
|
@Nullable
|
@Override
|
public T get() {
|
return (supplier == null) ? value : computeValue();
|
}
|
|
@Nullable
|
private synchronized T computeValue() {
|
final Supplier<? extends T> s = supplier;
|
if (s != null) {
|
value = s.get();
|
supplier = null;
|
}
|
return value;
|
}
|
|
}
|