Hibernate辅助实现系统目录的树形结构的打印

Everything is code......

首先是位于src下的Hibernate核心配置文件

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
	<session-factory>
		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="connection.url">jdbc:mysql://localhost:3306/jadyer?characterEncoding=UTF-8</property>
		<property name="connection.username">root</property>
		<property name="connection.password">hongyu</property>
		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
		<!-- 不要输出SQL语句，否则会影响树形结构的打印效果 -->
		<!--
		<property name="hibernate.show_sql">true</property>
		<property name="hibernate.format_sql">true</property>
		-->
		<mapping resource="com/jadyer/hibernate/Node.hbm.xml" />
	</session-factory>
</hibernate-configuration>

然后是用到的实体类映射文件Node.hbm.xml

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.jadyer.hibernate.Node" table="t_node">
		<id name="id">
			<generator class="native" />
		</id>
		<property name="name" />
		<property name="level" />
		<property name="leaf" />
		<many-to-one name="parent" column="pid" />
		<set name="children" lazy="extra" inverse="true">
			<key column="pid" />
			<one-to-many class="com.jadyer.hibernate.Node" />
		</set>
	</class>
</hibernate-mapping>

接下来就是实体类Node.java

package com.jadyer.hibernate;

import java.util.Set;

public class Node {
	private int id;             // 标识符
	private String name;        // 节点名称
	private int level;          // 层次
	private boolean leaf;       // 是否是叶子节点
	private Node parent;        // 父节点 * --- 1
	private Set<Node> children; // 子节点 1 --- *
	/*--六个属性对应的setter和getter略--*/
}

然后是利用Hibernate映射文件生成Table的Java类

package com.jadyer.hibernate;

import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

/**
 * 利用Hibernate映射文件生成数据表
 */
public class ExportDB {
	public static void main(String[] args) {
		// 读取hibernate.cfg.xml文件
		Configuration cfg = new Configuration().configure();
		// 创建SchemaExport对象
		SchemaExport export = new SchemaExport(cfg);
		// 创建数据库表
		export.create(true, true);
	}
}

下面是自定义的用于生成Session的工具类

package com.jadyer.hibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateSessionUtils {
	private static SessionFactory factory;
	
	static {
		Configuration cfg = new Configuration().configure();
		factory = cfg.buildSessionFactory();
	}
	
	public static Session getSession() {
		return factory.openSession();
	}
	
	public static void closeSession(Session session) {
		if (null != session && session.isOpen()) {
			session.close();
		}
	}
}

下面就是核心的节点处理类NodeManager.java

package com.jadyer.hibernate;

import java.io.File;
import java.util.Set;
import org.hibernate.Session;

/**
 * 节点处理类
 * @see 这里用到了递归
 */
public class NodeManager {
	private static NodeManager nodeManager;

	private NodeManager() {}

	public static synchronized NodeManager getInstance() {
		if (null == nodeManager) {
			nodeManager = new NodeManager();
		}
		return nodeManager;
	}

	/**
	 * 创建树型结构
	 */
	public void createTree(String dir) {
		Session session = HibernateSessionUtils.getSession();
		try {
			session.beginTransaction();
			File root = new File(dir);
			saveTree(root, session, null, 0);
			session.getTransaction().commit();
		} catch (RuntimeException e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		} finally {
			HibernateSessionUtils.closeSession(session);
		}
	}

	private void saveTree(File file, Session session, Node parent, int level) {
		if (null == file || !file.exists()) {
			return;
		}
		boolean isLeaf = file.isFile();
		Node node = new Node();
		node.setName(file.getName());
		node.setLevel(level);
		node.setParent(parent);
		node.setLeaf(isLeaf);
		session.save(node);
		File[] subs = file.listFiles();
		if (null != subs && subs.length > 0) {
			for (int i = 0; i < subs.length; i++) {
				saveTree(subs[i], session, node, level + 1);
			}
		}
	}

	public void printTree(int id) {
		Session session = HibernateSessionUtils.getSession();
		try {
			session.beginTransaction();
			Node root = (Node) session.load(Node.class, id);
			printNode(root);
			session.getTransaction().commit();
		} catch (RuntimeException e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		} finally {
			HibernateSessionUtils.closeSession(session);
		}
	}

	private void printNode(Node node) {
		if (null == node) {
			return;
		}
		int level = node.getLevel();
		if (0 < level) {
			for (int i = 0; i < level; i++) {
				System.out.print("  |");
			}
			System.out.print("--");
		}
		System.out.println(node.getName() + (node.isLeaf() ? "" : "[" + node.getChildren().size() + "]"));
		Set<Node> children = node.getChildren();
		for (Node child : children) {
			printNode(child);
		}
	}
}

最后是借助JUnit3.8实现的单元测试类

package com.jadyer.hibernate;

import com.jadyer.hibernate.NodeManager;
import junit.framework.TestCase;

/**
 * 树形结构测试类
 * @see 测试时需要利用JUnit进行单元测试
 * @see 首先执行ExportDB.main()方法
 * @see 然后执行testCreateTree()方法
 * @see 最后执行testPrintTree()方法
 */
public class NodeManagerTest extends TestCase {
	/** 
	 * 递归读取相应目录，并把它存放到数据库表中
	 * 该方法用来为testPrintTree()的执行准备数据
	 */
	public void testCreateTree() {
		NodeManager.getInstance().createTree("E://Develop//MyWorkspace//hibernate_tree//");
	}

	/**
	 * 输出节点为 1 的节点，其实就是根节点
	 */
	public void testPrintTree() {
		NodeManager.getInstance().printTree(1);
	}
}

下面就是在控制台上打印输出的结果

hibernate_tree[4]
  |--src[2]
  |  |--hibernate.cfg.xml
  |  |--com[1]
  |  |  |--jadyer[1]
  |  |  |  |--hibernate[6]
  |  |  |  |  |--HibernateSessionUtils.java
  |  |  |  |  |--Node.java
  |  |  |  |  |--Node.hbm.xml
  |  |  |  |  |--NodeManagerTest.java
  |  |  |  |  |--NodeManager.java
  |  |  |  |  |--ExportDB.java
  |--.classpath
  |--.project
  |--bin[2]
  |  |--hibernate.cfg.xml
  |  |--com[1]
  |  |  |--jadyer[1]
  |  |  |  |--hibernate[6]
  |  |  |  |  |--HibernateSessionUtils.class
  |  |  |  |  |--NodeManagerTest.class
  |  |  |  |  |--Node.class
  |  |  |  |  |--Node.hbm.xml
  |  |  |  |  |--NodeManager.class
  |  |  |  |  |--ExportDB.class