上回说到：
Intellij IDEA下的第一个Hibernate项目
。我们需要创建 对象到关系的映射配置文件，如 entity.hbm.xml。（其中 entity 是我们将要创建的实体）
下面讲的是 使用 注解 实现不用配置文件的对象到关系的映射过程。针对上一回讲到的在Intellij IDEA下创建Hibernate项目，这一次我们同样按照类似的步骤创建一个新的Module，这里我创建一个 Hibernate_01 Module。
接下创建一个 Students 实体：
选择 hibernate.cfg.xml 右键，选择创建实体Entity（记得 要先按照上回讲到的，创建相应的 Hibernate 的配置文件 hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql:///hibernate?useUnicode=true&characterEncoding=UTF-8</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="hbm2ddl.auto">create</property>
<!-- DB schema will be updated if needed -->
<!-- <property name="hbm2ddl.auto">update</property> -->
</session-factory>
</hibernate-configuration>
）：
选择在 entity 包下创建：
创建成功后，在Hibernate配置文件中会自动添加一行映射关系：
Students.java
package entity;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import java.util.Date;
/**
* Created by DreamBoy on 2016/5/16.
*/
@Entity
public class Students {
private int sid;
private String sname;
private String gender;
private Date birthday;
private String address;
public Students(int sid, String sname, String gender, Date birthday, String address) {
this.sid = sid;
this.sname = sname;
this.gender = gender;
this.birthday = birthday;
this.address = address;
}
@Id
@Column(name = "sid")
public int getSid() {
return sid;
}
public void setSid(int sid) {
this.sid = sid;
}
@Basic
@Column(name = "sname")
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
@Basic
@Column(name = "gender")
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Basic
@Column(name = "birthday")
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Basic
@Column(name = "address")
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Students students = (Students) o;
if (sid != students.sid) return false;
if (sname != null ? !sname.equals(students.sname) : students.sname != null) return false;
if (gender != null ? !gender.equals(students.gender) : students.gender != null) return false;
if (birthday != null ? !birthday.equals(students.birthday) : students.birthday != null) return false;
if (address != null ? !address.equals(students.address) : students.address != null) return false;
return true;
}
@Override
public int hashCode() {
int result = sid;
result = 31 * result + (sname != null ? sname.hashCode() : 0);
result = 31 * result + (gender != null ? gender.hashCode() : 0);
result = 31 * result + (birthday != null ? birthday.hashCode() : 0);
result = 31 * result + (address != null ? address.hashCode() : 0);
return result;
}
}
创建 Main.java，内容如下：
import entity.Students;
import org.hibernate.*;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import java.util.Date;
/**
* Created by DreamBoy on 2016/5/15.
*/
public class Main {
/*private static final SessionFactory ourSessionFactory;
private static final ServiceRegistry serviceRegistry;
static {
try {
Configuration configuration = new Configuration();
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
ourSessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}
public static Session getSession() throws HibernateException {
return ourSessionFactory.openSession();
}
public static void main(final String[] args) throws Exception {
final Session session = getSession();
try {
System.out.println("querying all the managed entities...");
final Map metadataMap = session.getSessionFactory().getAllClassMetadata();
for (Object key : metadataMap.keySet()) {
final ClassMetadata classMetadata = (ClassMetadata) metadataMap.get(key);
final String entityName = classMetadata.getEntityName();
final Query query = session.createQuery("from " + entityName);
System.out.println("executing: " + query.getQueryString());
for (Object o : query.list()) {
System.out.println(" " + o);
}
}
} finally {
session.close();
}
}*/
public static void main(String[] args) {
//创建配置对象，获取hibernate.cfg.xml配置文件的信息
Configuration config = new Configuration().configure();
//创建服务注册对象，创建和销毁都相当耗费资源，通常一个系统内一个数据库只创建一个
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//创建会话工厂对象，类似于JDBC的Connection
SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
//会话对象
Session session = sessionFactory.openSession();
//开启事务
Transaction transaction = session.beginTransaction();
//生成学生对象
Students s = new Students(1, "张三丰", "男", new Date(), "武当山");
session.save(s); //保存对象进入数据库
transaction.commit(); //提交事务
session.close(); //关闭会话
sessionFactory.close(); //关闭会话工厂
}
}
运行Main.java，会看如下运行结果：
在 名为 hibernate 的数据库下 创建了 Students 表，并插入了一条数据。
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