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!766 EasyStream 对递归树结构的支持，提供结束操作toTree、中间操作flatTree函数
Merge pull request !766 from 阿超/v6-dev
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Looly
Gitee
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@ -1364,6 +1364,95 @@ public class EasyStream<T> implements Stream<T>, Iterable<T> {
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return collect(CollectorUtil.toMap(keyMapper, valueMapper, mergeFunction, mapSupplier));
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}
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/**
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* 将集合转换为树，默认用 {@code parentId == null} 作为顶部，内置一个小递归
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* 因为需要在当前传入数据里查找，所以这是一个结束操作
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*
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* @param idGetter id的getter对应的lambda，可以写作 {@code Student::getId}
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* @param pIdGetter parentId的getter对应的lambda，可以写作 {@code Student::getParentId}
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* @param childrenSetter children的setter对应的lambda，可以写作{ @code Student::setChildren}
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* @param <R> 此处是id、parentId的泛型限制
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* @return list 组装好的树
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* eg:
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* {@code List studentTree = EasyStream.of(students).toTree(Student::getId, Student::getParentId, Student::setChildren) }
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*/
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public <R extends Comparable<R>> List<T> toTree(Function<T, R> idGetter,
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Function<T, R> pIdGetter,
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BiConsumer<T, List<T>> childrenSetter) {
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Map<R, List<T>> pIdValuesMap = group(pIdGetter);
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return getChildrenFromMapByPidAndSet(idGetter, childrenSetter, pIdValuesMap, pIdValuesMap.get(null));
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}
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/**
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* 将集合转换为树，自定义树顶部的判断条件，内置一个小递归(没错，lambda可以写递归)
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* 因为需要在当前传入数据里查找，所以这是一个结束操作
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*
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* @param idGetter id的getter对应的lambda，可以写作 {@code Student::getId}
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* @param pIdGetter parentId的getter对应的lambda，可以写作 {@code Student::getParentId}
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* @param childrenSetter children的setter对应的lambda，可以写作 {@code Student::setChildren}
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* @param parentPredicate 树顶部的判断条件，可以写作 {@code s -> Objects.equals(s.getParentId(),0L) }
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* @param <R> 此处是id、parentId的泛型限制
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* @return list 组装好的树
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* eg:
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* {@code List studentTree = EasyStream.of(students).toTree(Student::getId, Student::getParentId, Student::setChildren, Student::getMatchParent) }
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*/
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public <R extends Comparable<R>> List<T> toTree(Function<T, R> idGetter,
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Function<T, R> pIdGetter,
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BiConsumer<T, List<T>> childrenSetter,
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Predicate<T> parentPredicate) {
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List<T> list = toList();
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List<T> parents = EasyStream.of(list).filter(e ->
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// 此处是为了适配 parentPredicate.test空指针 情况
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// 因为Predicate.test的返回值是boolean，所以如果 e -> null 这种返回null的情况，会直接抛出NPE
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Opt.ofTry(() -> parentPredicate.test(e)).filter(Boolean::booleanValue).isPresent())
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.toList();
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return getChildrenFromMapByPidAndSet(idGetter, childrenSetter, EasyStream.of(list).group(pIdGetter), parents);
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}
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/**
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* toTree的内联函数，内置一个小递归(没错，lambda可以写递归)
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* 因为需要在当前传入数据里查找，所以这是一个结束操作
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*
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* @param idGetter id的getter对应的lambda，可以写作 {@code Student::getId}
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* @param childrenSetter children的setter对应的lambda，可以写作 {@code Student::setChildren}
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* @param pIdValuesMap parentId和值组成的map，用来降低复杂度
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* @param parents 顶部数据
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* @param <R> 此处是id的泛型限制
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* @return list 组装好的树
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*/
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private <R extends Comparable<R>> List<T> getChildrenFromMapByPidAndSet(Function<T, R> idGetter,
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BiConsumer<T, List<T>> childrenSetter,
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Map<R, List<T>> pIdValuesMap,
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List<T> parents) {
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MutableObj<Consumer<List<T>>> recursiveRef = new MutableObj<>();
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Consumer<List<T>> recursive = values -> EasyStream.of(values, isParallel()).forEach(value -> {
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List<T> children = pIdValuesMap.get(idGetter.apply(value));
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childrenSetter.accept(value, children);
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recursiveRef.get().accept(children);
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});
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recursiveRef.set(recursive);
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recursive.accept(parents);
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return parents;
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}
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/**
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* 将树递归扁平化为集合，内置一个小递归(没错，lambda可以写递归)
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* 这是一个无状态中间操作
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*
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* @param childrenGetter 获取子节点的lambda，可以写作 {@code Student::getChildren}
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* @param childrenSetter 设置子节点的lambda，可以写作 {@code Student::setChildren}
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* @return EasyStream 一个流
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* eg:
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* {@code List students = EasyStream.of(studentTree).flatTree(Student::getChildren, Student::setChildren).toList() }
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*/
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public EasyStream<T> flatTree(Function<T, List<T>> childrenGetter, BiConsumer<T, List<T>> childrenSetter) {
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MutableObj<Function<T, EasyStream<T>>> recursiveRef = new MutableObj<>();
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Function<T, EasyStream<T>> recursive = e -> EasyStream.of(childrenGetter.apply(e)).flat(recursiveRef.get()).unshift(e);
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recursiveRef.set(recursive);
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return flat(recursive).peek(e -> childrenSetter.accept(e, null));
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}
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/**
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* 通过给定分组依据进行分组
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@ -3,13 +3,18 @@ package cn.hutool.core.stream;
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import cn.hutool.core.collection.ListUtil;
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import cn.hutool.core.map.MapUtil;
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import lombok.Builder;
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import lombok.Data;
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import lombok.experimental.Tolerate;
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import org.junit.Assert;
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import org.junit.Test;
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import java.util.*;
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import java.util.function.Consumer;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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import static java.util.Arrays.asList;
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import static java.util.Collections.singletonList;
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/**
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@ -427,6 +432,126 @@ public class EasyStreamTest {
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Assert.assertTrue(EasyStream.of(1).isNotEmpty());
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}
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@Test
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public void testToTree() {
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Consumer<Object> test = o -> {
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List<Student> studentTree = EasyStream
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.of(
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Student.builder().id(1L).name("dromara").build(),
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Student.builder().id(2L).name("baomidou").build(),
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Student.builder().id(3L).name("hutool").parentId(1L).build(),
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Student.builder().id(4L).name("sa-token").parentId(1L).build(),
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Student.builder().id(5L).name("mybatis-plus").parentId(2L).build(),
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Student.builder().id(6L).name("looly").parentId(3L).build(),
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Student.builder().id(7L).name("click33").parentId(4L).build(),
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Student.builder().id(8L).name("jobob").parentId(5L).build()
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)
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// just 3 lambda,top parentId is null
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.toTree(Student::getId, Student::getParentId, Student::setChildren);
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Assert.assertEquals(asList(
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Student.builder().id(1L).name("dromara")
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.children(asList(Student.builder().id(3L).name("hutool").parentId(1L)
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.children(singletonList(Student.builder().id(6L).name("looly").parentId(3L).build()))
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.build(),
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Student.builder().id(4L).name("sa-token").parentId(1L)
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.children(singletonList(Student.builder().id(7L).name("click33").parentId(4L).build()))
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.build()))
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.build(),
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Student.builder().id(2L).name("baomidou")
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.children(singletonList(
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Student.builder().id(5L).name("mybatis-plus").parentId(2L)
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.children(singletonList(
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Student.builder().id(8L).name("jobob").parentId(5L).build()
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))
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.build()))
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.build()
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), studentTree);
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};
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test = test.andThen(o -> {
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List<Student> studentTree = EasyStream
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.of(
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Student.builder().id(1L).name("dromara").matchParent(true).build(),
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Student.builder().id(2L).name("baomidou").matchParent(true).build(),
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Student.builder().id(3L).name("hutool").parentId(1L).build(),
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Student.builder().id(4L).name("sa-token").parentId(1L).build(),
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Student.builder().id(5L).name("mybatis-plus").parentId(2L).build(),
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Student.builder().id(6L).name("looly").parentId(3L).build(),
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Student.builder().id(7L).name("click33").parentId(4L).build(),
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Student.builder().id(8L).name("jobob").parentId(5L).build()
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)
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// just 4 lambda ,top by condition
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.toTree(Student::getId, Student::getParentId, Student::setChildren, Student::getMatchParent);
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Assert.assertEquals(asList(
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Student.builder().id(1L).name("dromara").matchParent(true)
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.children(asList(Student.builder().id(3L).name("hutool").parentId(1L)
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.children(singletonList(Student.builder().id(6L).name("looly").parentId(3L).build()))
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.build(),
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Student.builder().id(4L).name("sa-token").parentId(1L)
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.children(singletonList(Student.builder().id(7L).name("click33").parentId(4L).build()))
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.build()))
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.build(),
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Student.builder().id(2L).name("baomidou").matchParent(true)
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.children(singletonList(
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Student.builder().id(5L).name("mybatis-plus").parentId(2L)
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.children(singletonList(
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Student.builder().id(8L).name("jobob").parentId(5L).build()
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))
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.build()))
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.build()
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), studentTree);
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});
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test.accept(new Object());
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}
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@Test
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public void testFlatTree() {
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List<Student> studentTree = asList(
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Student.builder().id(1L).name("dromara")
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.children(asList(Student.builder().id(3L).name("hutool").parentId(1L)
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.children(singletonList(Student.builder().id(6L).name("looly").parentId(3L).build()))
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.build(),
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Student.builder().id(4L).name("sa-token").parentId(1L)
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.children(singletonList(Student.builder().id(7L).name("click33").parentId(4L).build()))
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.build()))
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.build(),
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Student.builder().id(2L).name("baomidou")
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.children(singletonList(
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Student.builder().id(5L).name("mybatis-plus").parentId(2L)
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.children(singletonList(
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Student.builder().id(8L).name("jobob").parentId(5L).build()
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))
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.build()))
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.build()
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);
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Assert.assertEquals(asList(
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Student.builder().id(1L).name("dromara").build(),
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Student.builder().id(2L).name("baomidou").build(),
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Student.builder().id(3L).name("hutool").parentId(1L).build(),
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Student.builder().id(4L).name("sa-token").parentId(1L).build(),
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Student.builder().id(5L).name("mybatis-plus").parentId(2L).build(),
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Student.builder().id(6L).name("looly").parentId(3L).build(),
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Student.builder().id(7L).name("click33").parentId(4L).build(),
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Student.builder().id(8L).name("jobob").parentId(5L).build()
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), EasyStream.of(studentTree).flatTree(Student::getChildren, Student::setChildren).sorted(Comparator.comparingLong(Student::getId)).toList());
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}
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@Data
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@Builder
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public static class Student {
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private String name;
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private Integer age;
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private Long id;
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private Long parentId;
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private List<Student> children;
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private Boolean matchParent = false;
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@Tolerate
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public Student() {
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// this is an accessible parameterless constructor.
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}
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}
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@Test
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public void testTransform() {
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final boolean result = EasyStream.of(1, 2, 3)
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