設(shè)計(jì)及封裝無限層級的樹狀結(jié)構(gòu)

需求：電商項(xiàng)目中，在商品的品類管理模塊抄囚，會(huì)涉及到遞歸調(diào)用出該節(jié)點(diǎn)的所有子節(jié)點(diǎn)的操作绍撞。

數(shù)據(jù)表設(shè)計(jì)：

category表.jpg

Category:

public class Category {
    private Integer id;

    private Integer parentId;

    private String name;

    private Boolean status;

    private Integer sortOrder;

    private Date createTime;

    private Date updateTime;

    @Override
    public boolean equals(Object o){
        if(this == o){
            return true;
        }
        if(o == null || getClass() != o.getClass()){
            return false;
        }
        Category category = (Category) o;
        return !(id!=null?!id.equals(category.id):category.id!=null);
    }

    @Override
    public int hashCode(){
        return id!=null?id.hashCode():0;
    }
}

Controller:

/**
 * 根據(jù)傳的categoryId獲取當(dāng)前categoryId下邊節(jié)點(diǎn)的category信息（平級，無遞歸）
 * @param session
 * @param categoryId
 * @return
 */
@RequestMapping("get_category.do")
@ResponseBody
public ServerResponse getChildrenParallelCategory(HttpSession session,
                                                  @RequestParam(value = "categoryId",defaultValue = "0") Integer categoryId){
    User user = (User)session.getAttribute(Const.CURRENT_USER);
    if(user == null){
        return ServerResponse.createByErrorCodeMessage(ResponseCode.NEED_LOGIN.getCode(),"用戶未登錄拣展，請先登錄");
    }
    if(iUserService.checkAdminRole(user).isSuccess()){
        //查詢子節(jié)點(diǎn)的category信息坡垫，并且不遞歸梭灿，保持平級
        return iCategoryService.getChildrenParallelCategory(categoryId);
    }else {
        return ServerResponse.createByErrorMessage("無權(quán)限操作，需要管理員權(quán)限");
    }
}


/**
 * 獲取當(dāng)前的categoryId并且遞歸查詢它的子節(jié)點(diǎn)的categoryId
 * @param session
 * @param categoryId
 * @return
 */
@RequestMapping("get_deep_category.do")
@ResponseBody
public ServerResponse getCategoryAndDeepChildrenCategory(HttpSession session,
                                                  @RequestParam(value = "categoryId",defaultValue = "0") Integer categoryId){

    User user = (User)session.getAttribute(Const.CURRENT_USER);
    if(user == null){
        return ServerResponse.createByErrorCodeMessage(ResponseCode.NEED_LOGIN.getCode(),"用戶未登錄冰悠，請先登錄");
    }
    if(iUserService.checkAdminRole(user).isSuccess()){
        //查詢當(dāng)前節(jié)點(diǎn)的id和遞歸子節(jié)點(diǎn)的id
        return iCategoryService.selectCategoryAndChildrenById(categoryId);
    }else {
        return ServerResponse.createByErrorMessage("無權(quán)限操作堡妒，需要管理員權(quán)限");
    }
}

ServiceImpl:

@Override
public ServerResponse<List<Category>> getChildrenParallelCategory(Integer categoryId){
    List<Category> categoryList = categoryMapper.selectCategoryChildrenParentId(categoryId);
    if(CollectionUtils.isEmpty(categoryList)){
        logger.info("未找到當(dāng)前分類的子分類");
    }
    return ServerResponse.createBySuccess(categoryList);
}

/**
 * 遞歸查詢本節(jié)點(diǎn)的id及其子孫節(jié)點(diǎn)的id：獲取當(dāng)前categoryId下的子節(jié)點(diǎn)，還要繼續(xù)查找子節(jié)點(diǎn)是否還有子節(jié)點(diǎn)屿脐，及所有子孫節(jié)點(diǎn)
 * 0-->10-->100
 * 如果傳0涕蚤，會(huì)返回10和100
 * 如果傳10，會(huì)返回100
 * @param categoryId
 * @return
 */
@Override
public ServerResponse<List<Integer>> selectCategoryAndChildrenById(Integer categoryId){
    HashSet<Category> categorySet = Sets.newHashSet();
    findChildCategory(categorySet,categoryId);

    List<Integer> categoryIdList = Lists.newArrayList();
    if(categoryId!=null){
        for(Category categoryItem : categorySet){
            categoryIdList.add(categoryItem.getId());
        }
    }
    return ServerResponse.createBySuccess(categoryIdList);
}

遞歸算法：

/**
 * 為了使使用set集合不重復(fù)的诵，需要重寫hashcode和equals方法
 * 遞歸算法：算出子節(jié)點(diǎn)
 * @param categorySet
 * @param categoryId
 * @return
 */
private Set<Category> findChildCategory(Set<Category> categorySet,Integer categoryId){
    Category category = categoryMapper.selectByPrimaryKey(categoryId);
    if(category!=null){
        categorySet.add(category);
    }
    //查找子節(jié)點(diǎn)万栅，遞歸算法一定要有一個(gè)退出的條件
    List<Category> categoryList = categoryMapper.selectCategoryChildrenParentId(categoryId);
    for(Category categoryItem:categoryList){
        findChildCategory(categorySet,categoryItem.getId());
    }
    return categorySet;
}

mapper：

public interface CategoryMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(Category record);

    int insertSelective(Category record);

    Category selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(Category record);

    int updateByPrimaryKey(Category record);

    /**
     * 根據(jù)categoryId獲取孩子節(jié)點(diǎn)的category信息
     * @param parentId
     * @return
     */
    List<Category> selectCategoryChildrenParentId(Integer parentId);
}

xml：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.hcxmall.dao.CategoryMapper" >
  <resultMap id="BaseResultMap" type="com.hcxmall.pojo.Category" >
    <constructor>
      <idArg column="id" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="parent_id" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="name" jdbcType="VARCHAR" javaType="java.lang.String" />
      <arg column="status" jdbcType="BIT" javaType="java.lang.Boolean" />
      <arg column="sort_order" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="create_time" jdbcType="TIMESTAMP" javaType="java.util.Date" />
      <arg column="update_time" jdbcType="TIMESTAMP" javaType="java.util.Date" />
    </constructor>
  </resultMap>
  <sql id="Base_Column_List" >
    id, parent_id, name, status, sort_order, create_time, update_time
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from mmall_category
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from mmall_category
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.hcxmall.pojo.Category" >
    insert into mmall_category (id, parent_id, name, 
      status, sort_order, create_time, 
      update_time)
    values (#{id,jdbcType=INTEGER}, #{parentId,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, 
      #{status,jdbcType=BIT}, #{sortOrder,jdbcType=INTEGER},now(),
      now())
  </insert>
  <insert id="insertSelective" parameterType="com.hcxmall.pojo.Category" >
    insert into mmall_category
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        id,
      </if>
      <if test="parentId != null" >
        parent_id,
      </if>
      <if test="name != null" >
        name,
      </if>
      <if test="status != null" >
        status,
      </if>
      <if test="sortOrder != null" >
        sort_order,
      </if>
      <if test="createTime != null" >
        create_time,
      </if>
      <if test="updateTime != null" >
        update_time,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=INTEGER},
      </if>
      <if test="parentId != null" >
        #{parentId,jdbcType=INTEGER},
      </if>
      <if test="name != null" >
        #{name,jdbcType=VARCHAR},
      </if>
      <if test="status != null" >
        #{status,jdbcType=BIT},
      </if>
      <if test="sortOrder != null" >
        #{sortOrder,jdbcType=INTEGER},
      </if>
      <if test="createTime != null" >
        now(),
      </if>
      <if test="updateTime != null" >
        now(),
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.hcxmall.pojo.Category" >
    update mmall_category
    <set >
      <if test="parentId != null" >
        parent_id = #{parentId,jdbcType=INTEGER},
      </if>
      <if test="name != null" >
        name = #{name,jdbcType=VARCHAR},
      </if>
      <if test="status != null" >
        status = #{status,jdbcType=BIT},
      </if>
      <if test="sortOrder != null" >
        sort_order = #{sortOrder,jdbcType=INTEGER},
      </if>
      <if test="createTime != null" >
        create_time = #{createTime,jdbcType=TIMESTAMP},
      </if>
      <if test="updateTime != null" >
        update_time = now(),
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.hcxmall.pojo.Category" >
    update mmall_category
    set parent_id = #{parentId,jdbcType=INTEGER},
      name = #{name,jdbcType=VARCHAR},
      status = #{status,jdbcType=BIT},
      sort_order = #{sortOrder,jdbcType=INTEGER},
      create_time = #{createTime,jdbcType=TIMESTAMP},
      update_time = now()
    where id = #{id,jdbcType=INTEGER}
  </update>

  <select id="selectCategoryChildrenParentId" resultMap="BaseResultMap" parameterType="int">
    SELECT <include refid="Base_Column_List"/>
    FROM mmall_category
    WHERE parent_id = #{parentId}
  </select>
</mapper>