Hibernate-對象關係映射框架

Hibernate簡介

hibernate是一個開源的ORM（對象關係映射）框架，也是一個持久層的框架，它對JDBC做了非常輕量級的封裝。

Hibernate核心（六大接口+配置文件）

Configuration：負責配置並啓動Hibernate

SessionFactory：負責初始化Hibernate

Session：負責持久化對象的CRUD操作

Transaction：負責事務

Query和Criteria：負責執行各種數據庫查詢

Hibernate工作原理

1. 通過Configuration config = new Configuration().configure();//讀取並解析hibernate.cfg.xml配置文件
2. 由hibernate.cfg.xml中的<mapping resource = "com/xx/xx.hbm.xml" />//讀取並解析映射信息
3. 通過SessionFactory sf = config.buildSessionFactory();//創建SessionFactory會話工廠
4. Session session = sf.openSession();//打開Session
5. Transaction tx = session.beginTransaction();//創建並啓動事務
6. persistent operate CRUD//數據持久化操作
7. tx.commit();//提交事務
8. 關閉Session
9. 關閉SesstionFactory

開發步驟：

1. 創建Hibernate的配置文件
2. 創建持久化類
3. 創建對象-關係映射文件
4. 通過Hibernate API編寫訪問數據庫的代碼

Hibernate開發實例

• 使用版本：Hibernate 4.2.4 + Mysql

1. 導入Hibernate必須的jar包（Hibernate-release-4.2.4.Final\lib\required）
2. 導入Mysql的jdbc驅動（mysql-connector-java-5.1.7-bin.jar）
3. 導入Junit4的jar包（Junit單元測試工具）//測試用

• 創建Hibernate的配置文件 hibernate.cfg.xml

1. <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
2. <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
3. <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/students</property>
4. <property name="hibernate.connection.username">root</property>
   
5. <property name="hibernate.connection.password">root</property>

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE hibernate-configuration PUBLIC 
   		"-//Hibernate/Hibernate Configuration DTD 3.0//EN" 
   		"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
   <hibernate-configuration>
   	<session-factory>
   		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
   		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
   		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/students</property>
   		<property name="hibernate.connection.username">root</property>
   		<property name="hibernate.connection.password">root</property>
   		<property name="hibernate.show_sql">true</property>
   		<property name="hibernate.hbm2ddl.auto">update</property>
   		<property name="hibernate.format_sql">true</property>
   	</session-factory>
   </hibernate-configuration>

   
   

• 創建持久化類

  import java.util.Date;
  
  //學生類
  public class Students {
  
  	private int sid;// 學號
  	private String sname;// 姓名
  	private String gender;// 性別
  	private Date birthday;// 出生日期
  	private String address;// 地址
  
  	public Students() {
  
  	}
  
  	public Students(int sid, String sname, String gender, Date birthday,
  			String address) {
  		// super();
  		this.sid = sid;
  		this.sname = sname;
  		this.gender = gender;
  		this.birthday = birthday;
  		this.address = address;
  	}
  
  	public int getSid() {
  		return sid;
  	}
  
  	public void setSid(int sid) {
  		this.sid = sid;
  	}
  
  	public String getSname() {
  		return sname;
  	}
  
  	public void setSname(String sname) {
  		this.sname = sname;
  	}
  
  	public String getGender() {
  		return gender;
  	}
  
  	public void setGender(String gender) {
  		this.gender = gender;
  	}
  
  	public Date getBirthday() {
  		return birthday;
  	}
  
  	public void setBirthday(Date birthday) {
  		this.birthday = birthday;
  	}
  
  	public String getAddress() {
  		return address;
  	}
  
  	public void setAddress(String address) {
  		this.address = address;
  	}
  
  	@Override
  	public String toString() {
  		return "Students [sid=" + sid + ", sname=" + sname + ", gender="
  				+ gender + ", birthday=" + birthday + ", address=" + address
  				+ "]";
  	}
  
  }
  

  
  
• 創建對象-關係映射文件 Students.hbm.xml

  <?xml version="1.0"?>
  <!DOCTYPE hibernate-mapping PUBLIC
  	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
  	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
  <hibernate-mapping>
   	<class name="Students" table="STUDENTS">
   		<id name="sid" type="int">
   			<column name="SID" />
   			<generator class="assigned" />
   		</id>
   		<property name="sname" type="java.lang.String">
   			<column name="SNAME" />
   		</property>
   		<property name="gender" type="java.lang.String">
   			<column name="GENEDER" />
   		</property>
   		<property name="birthday" type="java.util.Data">
   			<column name="BIRTHDAY" />
   		</property>
   		<property name="address" type="java.lang.String">
   			<column name="ADDRESS" />
   		</property>
    	</class>
  </hibernate-mapping>

  
  
• 將Students.hbm.xml加入hibernate.cfg.xml

  <mapping resource="Students.hbm.xml" />

  
  
• 創建數據庫students 刷新表就會自動產生students表

• 使用Junit進行測試

1. @Test：測試方法
2. @Before：初始化方法
3. @After：釋放資源

• 通過Hibernate API編寫訪問數據庫的代碼

1. Configuration config = new Configuration().configure();//創建配置對象
2. ServiceRegistry seviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();//創建服務註冊對象
3. sessionFactory = config.buildSessionFactory(serviceRegistry);//創建會話工廠對象
4. session = sessionFactory.openSession();//打開對話

   package Test;
   
   import java.util.Date;
   
   import org.hibernate.Session;
   import org.hibernate.SessionFactory;
   import org.hibernate.Transaction;
   import org.hibernate.cfg.Configuration;
   import org.hibernate.service.ServiceRegistry;
   import org.hibernate.service.ServiceRegistryBuilder;
   import org.junit.After;
   import org.junit.Before;
   import org.junit.Test;
   
   import com.Students;
   
   //測試類
   public class StudentTest {
   	
   	private SessionFactory sessionFactory;
   	private Session session;
   	private Transaction transation;
   	
   	@Before
   	public void init() {
   		Configuration config = new Configuration().configure();
   		ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
   		sessionFactory = config.buildSessionFactory(serviceRegistry);
   		session = sessionFactory.openSession();
   		transation = session.beginTransaction();
   	}
   	
   	@After
   	public void destory() {
   		transation.commit();//提交事務
   		session.close();//關閉會話
   		sessionFactory.close();//關閉會話工廠
   	}
   	
   	@Test
   	public void testSaveStudents() {
   		//生成學生對象
   		Students s = new Students(1, "小明", "男", new Date(), "中國");
   		session.save(s);//保存對象進入數據庫
   		
   		
   	}
   }