《hibernate一对多的自关联》

你的名字 2022-04-12 14:05 250阅读 0赞

**1.entity**

package com.zy.four.entity;
    
    import java.util.HashSet;
    import java.util.Set;
    
    public class TreeNode {
    	
    //	  tree_node_id int primary key auto_increment,                                              -- ID
    //	  tree_node_name varchar(50) not null,                                                      -- 名字
    //	  tree_node_type int not null check(tree_node_type = 1 or tree_node_type = 2),              -- 节点类型：1 枝节点 2 叶节点
    //
    //	  position int,                                                                             -- 位置
    //	  parent_node_id int,                                                                       -- 父节点ID
    //	  url varchar(1024),                                                                        -- URL
    //	  foreign key(parent_node_id) references t_hibernate_sys_tree_node(tree_node_id)
    	
    	private Integer tree_node_id;
    	private String tree_node_name;
    	private Integer tree_node_type;
    	private Integer position;
    	private String url;
    	private TreeNode parent;
    	private Set<TreeNode> children = new HashSet<>();
    	
    	public Integer getTree_node_id() {
    		return tree_node_id;
    	}
    	public void setTree_node_id(Integer tree_node_id) {
    		this.tree_node_id = tree_node_id;
    	}
    	public String getTree_node_name() {
    		return tree_node_name;
    	}
    	public void setTree_node_name(String tree_node_name) {
    		this.tree_node_name = tree_node_name;
    	}
    	public Integer getTree_node_type() {
    		return tree_node_type;
    	}
    	public void setTree_node_type(Integer tree_node_type) {
    		this.tree_node_type = tree_node_type;
    	}
    	public Integer getPosition() {
    		return position;
    	}
    	public void setPosition(Integer position) {
    		this.position = position;
    	}
    	public String getUrl() {
    		return url;
    	}
    	public void setUrl(String url) {
    		this.url = url;
    	}
    	public TreeNode getParent() {
    		return parent;
    	}
    	public void setParent(TreeNode parent) {
    		this.parent = parent;
    	}
    	public Set<TreeNode> getChildren() {
    		return children;
    	}
    	public void setChildren(Set<TreeNode> children) {
    		this.children = children;
    	}
    	
    	public TreeNode() {
    		super();
    	}
        public TreeNode(Integer tree_node_id, String tree_node_name, Integer tree_node_type, Integer position, String url,
    			TreeNode parent, Set<TreeNode> children) {
    		super();
    		this.tree_node_id = tree_node_id;
    		this.tree_node_name = tree_node_name;
    		this.tree_node_type = tree_node_type;
    		this.position = position;
    		this.url = url;
    		this.parent = parent;
    		this.children = children;
    	}
        
    	@Override
    	public String toString() {
    		return "TreeNode [tree_node_id=" + tree_node_id + ", tree_node_name=" + tree_node_name + ", tree_node_type="
    				+ tree_node_type + ", position=" + position + ", url=" + url + ", parent=" + parent + ", children="
    				+ children + "]";
    	}
        
        
    
    }

**2.entity.hbm.xml**

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC 
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
        
    	<class name="com.zy.four.entity.TreeNode" table="t_hibernate_sys_tree_node">
    	    
    		<id name="tree_node_id" type="java.lang.Integer" column="tree_node_id">
    		    
    			<generator class="increment"/> 
    		</id>
    		
    		
    		<property name="tree_node_name" type="java.lang.String" column="tree_node_name"></property>
    		<property name="tree_node_type" type="java.lang.Integer" column="tree_node_type"></property>
    		<property name="position" type="java.lang.Integer" column="position"></property>
    		<property name="url" type="java.lang.String" column="url"></property>
    		
    		
    		<many-to-one name="parent" class="com.zy.four.entity.TreeNode" column="parent_node_id" ></many-to-one>
    		
    		
    		<set name="children">
    		 <key column="parent_node_id"></key>
    		 <one-to-many class="com.zy.four.entity.TreeNode"/>
    		</set>
    		
    	</class>
    </hibernate-mapping>

**3.hibernate.cfg.xml**

<mapping resource="com/zy/four/entity/TreeNode.hbm.xml"/>

**4.dao**

package com.zy.four.dao;
    
    import org.hibernate.Hibernate;
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    
    import com.zy.four.entity.TreeNode;
    import com.zy.two.util.SessionFactoryUtil;
    
    public class TreeNodeDao {
    	
    	/**
    	 * 查询方法
    	 * @param treeNode
    	 * @return
    	 */
    	public TreeNode get(TreeNode treeNode) {
    		Session session = SessionFactoryUtil.getSession(); //获取session会话
    		Transaction transaction = session.beginTransaction(); //开启事物
    		TreeNode tn = session.get(TreeNode.class, treeNode.getTree_node_id()); //操作数据库
    		Hibernate.initialize(tn.getParent()); //强制加载
    		Hibernate.initialize(tn.getChildren()); //强制加载
    		transaction.commit(); //提交事物
    		session.close(); //关闭会话
    		return tn;
    	}
    
    
    }

**5.daoTest**

package com.zy.four.dao;
    
    import static org.junit.Assert.*;
    
    import org.junit.Test;
    
    import com.zy.four.entity.TreeNode;
    
    public class TreeNodeDaoTest {
    	
    	private TreeNodeDao tnDao = new TreeNodeDao();
    
    	@Test
    	public void testGet() {
    		TreeNode treeNode = new TreeNode();
    		treeNode.setTree_node_id(6);
    		TreeNode treeNodes = tnDao.get(treeNode);
    		System.out.println("当前节点名称："+treeNodes.getTree_node_name());
    		System.out.println("父节点名称："+treeNodes.getParent().getTree_node_name());
    		System.out.println("子节点数量："+treeNodes.getChildren().size());
    	}
    
    }