使用要求：JDK版本大于等于1.8
import java.util.ArrayList;import java.util.List;import java.util.Map;import java.util.Objects;import java.util.function.BiConsumer;import java.util.function.Function;import java.util.stream.Collectors;public class TreeUtils {/*** 将数据转换为树状数据* @param list 原始数据* @param superGetter 上级标识字段（例：User::getParentId）* @param thisGetter 当前标识字段（例：User::getId）* @param nextSetter 下级数据存储字段（例：User::setUsers）* @return 树形数据*/public static <T, R> List<T> tree(List<T> list, Function<T, R> superGetter, Function<T, R> thisGetter, BiConsumer<T, List<T>> nextSetter) {Map<R, List<T>> map = list.stream().collect(Collectors.groupingBy(superGetter));List<T> tmp = new ArrayList<>(list);for (T node : list) {R apply = thisGetter.apply(node);List<T> ts = map.get(apply);if (ts != null && ts.size() > 0) {nextSetter.accept(node, ts);tmp.removeIf(ts::contains);}}return tmp;}/*** 将数据转换为树状数据* @param list 原始数据* @param root 根数据* @param superGetter 上级标识字段（例：User::getParentId）* @param thisGetter 当前标识字段（例：User::getId）* @param nextSetter 下级数据存储字段（例：User::setUsers）* @return 树形数据*/public static <T, R> List<T> tree(List<T> list, R root, Function<T, R> superGetter, Function<T, R> thisGetter, BiConsumer<T, List<T>> nextSetter) {Map<R, List<T>> map = list.stream().collect(Collectors.groupingBy(superGetter));List<T> result = new ArrayList<>();for (T node : list) {R apply = thisGetter.apply(node);List<T> ts = map.get(apply);if (ts != null && ts.size() > 0) {nextSetter.accept(node, ts);}R superValue = superGetter.apply(node);if (Objects.deepEquals(superValue, root)) {result.add(node);}}return result;}}
