Hibernate初学

落日映苍穹つ 2022-05-24 08:52 19阅读 0赞

**Hibernate是一个开放源代码的对象关系映射框架**

**1.对JDBC进行了非常轻量级的对象封装**

**2.将POJO与数据库表建立映射关系**

**3.是一个全自动的orm框架，hibernate可以自动生成SQL语句，自动执行**

**![20180524123332875][]**

**po类Student.java**

package beans.po;
    
    public class Student {
    	private String stuId;
    	private String stuName;
    	public String getStuId() {
    		return stuId;
    	}
    	public void setStuId(String stuId) {
    		this.stuId = stuId;
    	}
    	public String getStuName() {
    		return stuName;
    	}
    	public void setStuName(String stuName) {
    		this.stuName = stuName;
    	}
    	public String toString() {
    		return "Student [stuId=" + stuId + ", stuName=" + stuName + "]";
    	}
    	
    	
    }

**Factory类HibernateSessionFactory.java**

package beans.factory;
    
    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 threadLocal = new ThreadLocal();
        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;
    	}
    
    }

**dao层 StudentDao.java**

package beans.dao;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    
    import beans.factory.HibernateSessionFactory;
    import beans.po.Student;
    
    public class StudentDao {
    	
    	private Session session;
    	private Transaction tr;
    	
    	public StudentDao(){
    		session = HibernateSessionFactory.getSession();
    		tr =session.beginTransaction();
    	}
    	
    	public void close(){
    		try {
    			if(tr!=null){
    				tr.commit();
    			}
    			if(session!=null){
    				session.close();
    			}
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    	
    	//增
    	public boolean insertStudent(Student student){
    		boolean result = false;
    		
    		try {
    			session.save(student);
    			
    			result = true;
    		} catch (Exception e) {
    			e.printStackTrace();
    			tr.rollback();
    		} finally{
    			close();
    		}
    		
    		return result;
    		
    	}
    	//删
    	public boolean deleteStudent(Student student){
    		boolean result = false;
    		try {
    			session.delete(student);
    			result = true;
    		} catch (Exception e) {
    			e.printStackTrace();
    			tr.commit();
    		} finally{
    			close();
    		}
    		return result;
    	}
    	//改
    	public boolean updateStudent(Student student){
    		boolean result = false;
    		try {
    			session.delete(student);
    			result = true;
    		} catch (Exception e) {
    			e.printStackTrace();
    			tr.commit();
    		} finally{
    			close();
    		}
    		return result;
    	}
    	//更新表数据
    	public int executeUpdate(String sql){
    		int result = -1;
    		try {
    			result = session.createSQLQuery(sql).executeUpdate();
    			
    		} catch (Exception e) {
    			e.printStackTrace();
    		} finally{
    			close();
    		}
    		return result;
    	}
    	
    	//查询数据
    	public List executeQuery(String sql){
    		List<Object> list =null;
    		try {
    			list=session.createQuery(sql).list();
    		} catch (Exception e) {
    			e.printStackTrace();
    		} finally{
    			close();
    		}
    		return list;
    	}
    }

**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="beans.po.Student" table="student" catalog="test">
    		<id name="stuId" type="java.lang.String">
                <column name="stu_id" length="15" />
                <generator class="assigned" />
            </id>
            <property name="stuName" type="java.lang.String">
                <column name="stu_name" length="30" />
            </property>
    	</class>
    </hibernate-mapping>

**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="connection.username">root</property>
    		<property name="connection.password">mysql</property>
    		<property name="connection.url">jdbc:mysql://localhost:3308/test</property>
    		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    		<property name="myeclipse.connection.profile">lg</property>
    		<mapping resource="Student.hbm.xml"/>
    	</session-factory>         
    </hibernate-configuration>

[20180524123332875]: /images/20220524/5bb139d5a24f442b8c9299d03b9ae463.png