TreeUtil组装树工具类分享

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list转tree 工具类分享

学习使用java Function函数式编程抽象方法，以下是代码

  • TreeUtil.java工具类代码
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    import org.apache.commons.collections.CollectionUtils;

    import java.util.*;
    import java.util.function.BiConsumer;
    import java.util.function.Consumer;
    import java.util.function.Function;
    import java.util.function.Predicate;

    public class TreeUtil {

        /**
         * 树转平铺
         *
         * 示例
         * treeToListDeep(TreeVOs, result, TreeVO::getChildren(), l -> true);
         *
         * @param source             源数据
         * @param target             目标容器
         * @param childListFn        递归调用方法
         * @param addTargetCondition 添加到容器的判断方法
         */
        public static <F> void treeToListDeep(List<F> source, List<F> target, Function<F, List<F>> childListFn, Predicate<F> addTargetCondition) {
            loopTree(source, childListFn, l -> {
                if (addTargetCondition.test(l)) {
                    target.add(l);
                }
            });
        }
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        /**
         * 列表组装成树
         *
         * 示例
         * List<TreeVO> treeList = listToTree(list, TreeVO::setChildren, TreeVO::getId, TreeVO::getPid, (l) -> l.getPid() == null);
         *
         * @param source           源数据
         * @param setChildListFn   设置递归的方法
         * @param idFn             获取id的方法
         * @param pidFn            获取父id的方法
         * @param getRootCondition 获取根节点
         * @return {@link List<F>}
         */
        public static <F, T> List<F> listToTree(List<F> source, BiConsumer<F, List<F>> setChildListFn, Function<F, T> idFn, Function<F, T> pidFn, Predicate<F> getRootCondition) {
            return listToTree(source, setChildListFn, idFn, pidFn, getRootCondition, null);
        }

        /**
         * 列表组装成树 （可带回调函数 idx层级 0开始）
         *
         * @param listen 回调函数
         */
        public static <F, T> List<F> listToTree(List<F> source, BiConsumer<F, List<F>> setChildListFn, Function<F, T> idFn, Function<F, T> pidFn, Predicate<F> getRootCondition, BiConsumer<Integer, F> listen) {
            List<F> tree = new ArrayList<>();
            Map<T, List<F>> map = new HashMap<>(source.size());
            for (F f : source) {
                if (getRootCondition.test(f)) {
                    tree.add(f);
                } else {
                    List<F> tempList = map.getOrDefault(pidFn.apply(f), new ArrayList<>());
                    tempList.add(f);
                    map.put(pidFn.apply(f), tempList);
                }
            }
            tree.forEach(l -> assembleTree(l, map, setChildListFn, idFn, listen, 0));
            return tree;
        }

        /**
         * 组装树
         *
         */
        private static <F, T> void assembleTree(F current, Map<T, List<F>> map, BiConsumer<F, List<F>> setChildListFn, Function<F, T> idFn, BiConsumer<Integer, F> listen, int idx) {
            List<F> fs = map.get(idFn.apply(current));
            setChildListFn.accept(current, fs);
            if (CollectionUtils.isNotEmpty(fs)) {
                fs.forEach(l -> assembleTree(l, map, setChildListFn, idFn, listen, idx + 1));
            }
            if (listen != null) {
                listen.accept(idx, current);
            }
        }

        /**
         * 递归树
         *
         * @param source      源数据
         * @param childListFn get方法
         * @param listen      回调函数
         */
        public static <F> void loopTree(List<F> source, Function<F, List<F>> childListFn, Consumer<F> listen) {
            loopTree(source, childListFn, listen, null);
        }

        public static <F> void loopTree(List<F> source, Function<F, List<F>> childListFn, Consumer<F> preListen, Consumer<F> postFun) {
            if (CollectionUtils.isEmpty(source)) {
                return;
            }
            source.forEach(l -> {
                Optional.ofNullable(preListen).ifPresent(s -> s.accept(l));
                loopTree(childListFn.apply(l), childListFn, preListen, postFun);
                Optional.ofNullable(postFun).ifPresent(s -> s.accept(l));
            });
        }
    }
  • TreeUtilTest.java 测试类代码（使用示例）
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    import com.alibaba.fastjson.JSONArray;
    import com.alibaba.fastjson.serializer.SerializerFeature;
    import lombok.*;
    import lombok.extern.slf4j.Slf4j;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.test.context.junit4.SpringRunner;

    import java.util.ArrayList;
    import java.util.List;

    /**
     * @author yinshuang
     * @date 2022/1/20 9:18
     * @description TreeUtilTest
     * @copyright(c) chinacscs all rights reserved
     */
    @Slf4j
    @RunWith(SpringRunner.class)
    public class TreeUtilTest {

        @Data
        @EqualsAndHashCode()
        @AllArgsConstructor
        @NoArgsConstructor
        @ToString()
        @Builder
        // @JsonInclude(JsonInclude.Include.NON_EMPTY)
        static class TreeVO {
            /**
             * 节点id
             */
            private Integer id;

            /**
             * 节点标题
             */
            private String title;

            /**
             * 父节点id
             */
            private Integer pid;

            /**
             * 子层级
             */
            private List<TreeVO> children;
        }

        @Test
        public void testListToTree() {
            System.out.println("\n\n**********************************************组装前*******************************************\n\n");
            List<TreeVO> list = new ArrayList<TreeVO>() {{
                add(TreeVO.builder().id(310000).title("上海市").build());
                add(TreeVO.builder().id(310101).title("黄浦区").pid(310000).build());
                add(TreeVO.builder().id(310104).title("徐汇区").pid(310000).build());
                add(TreeVO.builder().id(310105).title("长宁区").pid(310000).build());
                add(TreeVO.builder().id(310106).title("静安区").pid(310000).build());
                add(TreeVO.builder().id(310107).title("普陀区").pid(310000).build());
                add(TreeVO.builder().id(310109).title("虹口区").pid(310000).build());
                add(TreeVO.builder().id(420000).title("湖北省").build());
                add(TreeVO.builder().id(420100).title("武汉市").pid(420000).build());
                add(TreeVO.builder().id(420102).title("江岸区").pid(420100).build());
                add(TreeVO.builder().id(420103).title("江汉区").pid(420100).build());
                add(TreeVO.builder().id(420104).title("硚口区").pid(420100).build());
                add(TreeVO.builder().id(420105).title("汉阳区").pid(420100).build());
                add(TreeVO.builder().id(420106).title("武昌区").pid(420100).build());
                add(TreeVO.builder().id(420107).title("青山区").pid(420100).build());
                add(TreeVO.builder().id(440000).title("广东省").build());
                add(TreeVO.builder().id(440100).title("广州市").pid(440000).build());
                add(TreeVO.builder().id(440103).title("荔湾区").pid(440100).build());
                add(TreeVO.builder().id(440104).title("越秀区").pid(440100).build());
                add(TreeVO.builder().id(440105).title("海珠区").pid(440100).build());
                add(TreeVO.builder().id(440106).title("天河区").pid(440100).build());
            }};
            //System.out.println(list.toString());
            String listJson = JSONArray.toJSONString(list, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue);
            System.out.println(listJson);

            System.out.println("\n\n**********************************************组装后*******************************************\n\n");

            List<TreeVO> tree = TreeUtil.listToTree(list, TreeVO::setChildren, TreeVO::getId, TreeVO::getPid, l -> l.getPid() == null);
            //System.out.println(treeResult.toString());
            String treeJson = JSONArray.toJSONString(tree, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue);
            System.out.println(treeJson);

            System.out.println("\n\n**********************************************平铺后*******************************************\n\n");
            List<TreeVO> listDeep = new ArrayList<>();
            TreeUtil.treeToListDeep(tree, listDeep, TreeVO::getChildren, l -> l.getTitle() != null);

            String listDeepJson = JSONArray.toJSONString(listDeep, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue);
            System.out.println(listDeep.toString());
            //System.out.println(listDeepJson);

            System.out.println("\n\n**********************************************结束*******************************************\n\n");
        }
    }
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    缺失模块。
    1、请确保node版本大于6.2
    2、在博客根目录（注意不是yilia-plus根目录）执行以下命令：
    npm i hexo-generator-json-content --save

    3、在根目录_config.yml里添加配置：

      jsonContent:
    meta: false
    pages: false
    posts:
      title: true
      date: true
      path: true
      text: false
      raw: false
      content: false
      slug: false
      updated: false
      comments: false
      link: false
      permalink: false
      excerpt: false
      categories: false
      tags: true

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