hibernate入門

hibernate自動建學生表

最近學習了hibernate，現在來整理一下做的一個小demo，根據配置文件在數據庫自動建立學生表。

準備工作：

        IDE工具：mysql+eclipse

        entity實體類+對應的配置文件：Student.java，Student.hbm.xml。實體類用於記錄實體Student的屬性和方法，實體類配置文件用於配置數據庫表與實體的對應關係。

        utils工具包:HibernateSessionFactory.java，用於獲取session。

  hibernate.cfg.xml總配置文件：配置屬性property，指定連接數據庫的driver，url，username，password，hbm2ddl.auto，show_sql。以及配置映射文件mapping。

        execute包：executeService.java，執行main方法。

        建立數據庫test：數據庫要手動建立，hibernate只會自動建表，不會自動建庫。

具體代碼如下：

Student.java：

package entity;
public class Student {

	private String student_id;
	private String sname;
	private int age;
	public String getStudent_id() {
		return student_id;
	}
	public void setStudent_id(String student_id) {
		this.student_id = student_id;
	}
	public String getSname() {
		return sname;
	}
	public void setSname(String sname) {
		this.sname = sname;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	@Override
	public String toString() {
		return "Student [student_id=" + student_id + ", sname=" + sname + ", age=" + age + "]";
	}
	

Student.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="entity.Student" table="student">
 		<id name="student_id" column="student_id">
 			<!-- 自動匹配MySQL或Oracle -->
			<!-- <generator class="native" />  -->
	         <!-- 程序指定 -->
			 <generator class="assigned" />  
 		</id>
 		
 		<property name="sname" column="sname" type="java.lang.String" ></property>
 		<property name="age" column="age" type="int" ></property>
 	</class>
 </hibernate-mapping>

HibernateSessionFactory.java

package utils;

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

public class HibernateSessionFactory {

    private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
    private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
    private  static Configuration configuration = new Configuration();    
    private static org.hibernate.SessionFactory sessionFactory;
    private static String configFile = CONFIG_FILE_LOCATION;

	static {
    	try {
			configuration.configure(configFile);
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			System.err
					.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
    }
    private HibernateSessionFactory() {
    }
	
    public static Session getSession() throws HibernateException {
        Session session = (Session) threadLocal.get();

		if (session == null || !session.isOpen()) {
			if (sessionFactory == null) {
				rebuildSessionFactory();
			}
			session = (sessionFactory != null) ? sessionFactory.openSession()
					: null;
			threadLocal.set(session);
		}
        return session;
    }

	public static void rebuildSessionFactory() {
		try {
			configuration.configure(configFile);
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			System.err
					.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
	}

    public static void closeSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);

        if (session != null) {
            session.close();
        }
    }

	public static org.hibernate.SessionFactory getSessionFactory() {
		return sessionFactory;
	}

	public static void setConfigFile(String configFile) {
		HibernateSessionFactory.configFile = configFile;
		sessionFactory = null;
	}
	public static Configuration getConfiguration() {
		return configuration;
	}

}

hibernate.cfg.xml:

<?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="hibernate.connection.url">
	    	jdbc:mysql://localhost:3306/test
	    </property>
       	<property name="hibernate.connection.driver_class">
       		com.mysql.jdbc.Driver
       	</property>
       	<!-- Hibernate格式化SQL語句 -->
		<property name="hibernate.format_sql">true</property>
		<!-- Hibernate的方言：作用，根據配置的方言生成相應的SQL語句-->
       	 <property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
       	<property name="hibernate.connection.username">root</property>
       	<property name="hibernate.connection.password">root</property>  
		<!-- 是否啓動表結構自動生成 -->
		<property name="hbm2ddl.auto">update</property>
		<!-- 是否在控制檯顯示SQL語句 -->
		<property name="show_sql">true</property>
            
        <!-- 2018-07-06 -->
         <mapping resource="entity/Student.hbm.xml" />
  
    </session-factory>
</hibernate-configuration>

executeService.java：

package execute;

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

public class executeService {

	public static void main(String[] args) {
		Configuration conf = new Configuration().configure();// 讀取並解析配置文件
		SchemaExport export = new SchemaExport(conf);// 創建SchemaExport
		// 執行生成表。參數1：是否顯示sql語句，參數2：是否到數據庫裏執行
		export.create(true, true);
	}
}

執行main方法，會發現數據庫自動建立了一個student表，至此成功入門hibernate，完成其配置文件的編寫。後面會將運用hibernate操作數據庫，實現增刪改查操作。