82 lines
2.3 KiB
Java
82 lines
2.3 KiB
Java
/**
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* Copyright (c) 2011-2019, James Zhan 詹波 (jfinal@126.com).
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.jfinal.template.ext.sharedmethod;
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import java.lang.reflect.Array;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.Map;
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/**
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* SharedMethodLib 共享方法库，逐步添加一些最常用的共享方法
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*
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* <br>
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* 3.3 版本之前的 Logic.isTrue(Object) 方法不再对 Collection、
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* Map、数组、Iterator、Iterable 进行为空的判断，这部分逻辑已转移至
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* SharedMethodLib.isEmpty(Object)
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*/
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public class SharedMethodLib {
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/**
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* 判断 Collection、Map、数组、Iterator、Iterable 类型对象中的元素个数是否为 0
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* 规则：
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* 1：null 返回 true
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* 2：List、Set 等一切继承自 Collection 的，返回 isEmpty()
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* 3：Map 返回 isEmpty()
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* 4：数组返回 length == 0
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* 5：Iterator 返回 ! hasNext()
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* 6：Iterable 返回 ! iterator().hasNext()
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*
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* 注意：原先 Logic.isTrue(Object) 中对集合与数组类型为空的判断转移到此方法中
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*/
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public Boolean isEmpty(Object v) {
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if (v == null) {
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return true;
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}
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if (v instanceof Collection) {
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return ((Collection<?>)v).isEmpty();
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}
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if (v instanceof Map) {
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return ((Map<?, ?>)v).isEmpty();
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}
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if (v.getClass().isArray()) {
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return Array.getLength(v) == 0;
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}
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if (v instanceof Iterator) {
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return ! ((Iterator<?>)v).hasNext();
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}
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if (v instanceof Iterable) {
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return ! ((Iterable<?>)v).iterator().hasNext();
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}
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throw new IllegalArgumentException("isEmpty(...) 方法只能接受 Collection、Map、数组、Iterator、Iterable 类型参数");
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}
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public Boolean notEmpty(Object v) {
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return !isEmpty(v);
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}
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}
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