Hibernate父子Tree

有一次要做一个行业分类的菜单，获取级联关系，由于是个新手，没有这方便的经验，做了很久才整出来一个蹩脚的方法，下面展示一下：

数据库：

CREATE TABLE `enterprise_type` (
  `c_id` int(11) NOT NULL auto_increment COMMENT '企业类型编号',
  `c_name` varchar(100) NOT NULL COMMENT '企业类型名称',
  `c_parentid` int(11) default NULL COMMENT '父类型编号',
  PRIMARY KEY  (`c_id`),
  KEY `FK_enterprise_type` (`c_parentid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

 

用Myeclipse的工具生成的实体类为：

 

// default package

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;

import static javax.persistence.GenerationType.IDENTITY;

import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;

/**
 * EnterpriseCategory entity. @author MyEclipse Persistence Tools
 */
@Entity
@Table(name = "enterprise_type", catalog = "")
public class EnterpriseCategory implements java.io.Serializable {

    // Fields

    private Integer CId;
    private EnterpriseCategory parentCategory;
    private String CName;
    private List<EnterpriseCategory> childCategory = new ArrayList<EnterpriseCategory>();

    // Property accessors
    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "c_id", unique = true, nullable = false)
    public Integer getCId() {
        return this.CId;
    }

    public void setCId(Integer CId) {
        this.CId = CId;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "c_parentid")
    public EnterpriseCategory getParentCategory() {
        return this.parentCategory;
    }

    public void setParentCategory(EnterpriseCategory parentCategory) {
        this.parentCategory = parentCategory;
    }

    @Column(name = "c_name", nullable = false, length = 100)
    public String getCName() {
        return this.CName;
    }

    public void setCName(String CName) {
        this.CName = CName;
    }

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "EnterpriseCategory")
    public List<EnterpriseCategory> getChildCategory() {
        return this.childCategory;
    }

    public void setChildCategory(
            List<EnterpriseCategory> childCategory) {
        this.childCategory = childCategory;
    }

}

 其他的不展示了，直接展示实现方法：

 

import org.apache.log4j.Category;
import org.hibernate.Criteria;
import org.hibernate.FetchMode;
import org.hibernate.criterion.Restrictions;
import org.springframework.stereotype.Repository;

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

/**
 * Created with IntelliJ IDEA.
 * User: Administrator
 * Date: 12-7-13
 * Time: 上午11:35
 * To change this template use File | Settings | File Templates.
 */
@Repository("enterpriseCategoryDao")
public class EnterpriseCategoryDaoHobernate extends EnterpriseAutoInjectGenericHibernateDAO<EnterpriseCategory, Integer> implements EnterpriseCategoryDao {

    /**
     * 根据给定的类别获取所有级联的cid
     *
     * @param id
     * @return
     */
    public List<Integer> getList(Integer id) {

        List<Integer> result = new ArrayList<Integer>();  //存放最终结果

        if (id == null) {
            return result;
        }
        List list = this.getSession().createCriteria(EnterpriseCategory.class)
                .setFetchMode("parentCategory", FetchMode.JOIN)
                .add(Restrictions.eq("parentCategory.CId", id))
                .list();
        if (list.size() == 0) {
            result.add(id);
        } else {
            result.add(id);
            result.addAll(add(list));
        }
        return result;
    }

    /**
     * @param list 得到的enterpriseCategory对象的集合
     * @return
     */
    public List<Integer> add(List list) {
        List<Integer> result = new ArrayList<Integer>();  //存放最终结果
        if (list.size() == 0) {
            return result;
        }
        try {
            for (int i = 0; i < list.size(); i++) {
                EnterpriseCategory childCategory = (EnterpriseCategory) list.get(i);
                result.add(childCategory.getCId());
                List<EnterpriseCategory> childList = childCategory.getChildCategory();
                if (childList.size() != 0) {
                    result.addAll(add(childList));
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }
}

 这样就能获取到级联关系的类型Tree，这个方法可以实现N层级联关系

下面是其他高手写的

实体类：

import javax.persistence.*;

import static javax.persistence.GenerationType.IDENTITY;

@Entity
@Table(name = "enterprise_type", catalog = "")
public class EnterpriseCategory implements java.io.Serializable {

    // Fields

    private Integer CId;
    private String CName;

    private Integer parentId;



    // Property accessors
    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "c_id", unique = true, nullable = false)
    public Integer getCId() {
        return this.CId;
    }

    public void setCId(Integer CId) {
        this.CId = CId;
    }

    @Column(name="c_parentid")
    public Integer getParentId() {
        return parentId;
    }

    public void setParentId(Integer parentId) {
        this.parentId = parentId;
    }

    @Column(name = "c_name", nullable = false, length = 100)
    public String getCName() {
        return this.CName;
    }

    public void setCName(String CName) {
        this.CName = CName;
    }
}

 实现方法：

private List<Integer> getCidList(Integer catId, boolean includeSelf) {
        List<Integer> ret = new ArrayList<Integer>();
        List<Integer> list = getSubCatList(catId);
        ret.addAll(list);
        if (!includeSelf) ret.remove(catId);
        return ret;

    }

    /**
     * 指定分类ID的所有子节点
     *
     * @param catId
     * @return
     */
    private List<Integer> getSubCatList(Integer catId) {
        List<EnterpriseCategory> allCats = enterpriseCategoryDao.loadAll();
        return getSubCatList(catId, allCats);
    }

    private List<Integer> getSubCatList(Integer cid, List<EnterpriseCategory> allCats) {

        Map<Integer, List<Integer>> FK_Parent_Child = new HashMap<Integer, List<Integer>>();
        for (EnterpriseCategory cat : allCats) {
            // 建立所有带有子节点的节点对应关系
            List<Integer> list = FK_Parent_Child.get(cat.getParentId());
            if (list == null) {
                list = new ArrayList<Integer>();
                list.add(cat.getCId());
                FK_Parent_Child.put(cat.getParentId(), list);
            } else {
                list.add(cat.getCId());
            }
        }

        return getSubCats(cid, FK_Parent_Child);
    }

    private List<Integer> getSubCats(Integer cid, Map<Integer, List<Integer>> FK_Parent_Child) {
        List<Integer> nodes = new ArrayList<Integer>();

        if (FK_Parent_Child.containsKey(cid)) {
            // 非叶子节点
            nodes.add(cid);
            List<Integer> childNodes = FK_Parent_Child.get(cid);
            for (Integer childId : childNodes) {
                nodes.addAll(getSubCats(childId, FK_Parent_Child));
            }
        } else {
            // 叶子节点
            nodes.add(cid);
        }
        return nodes;
    }

 

可以根据指定的ID获取下面的所有的子节点的id。

记下来，说不定以后会用到。虽然自己写的不怎么的，单也是辛苦的成果，记下来