hibernate helloWorld

entity:

package com.bxw.entity;

public class Student {
    private int id;
    private String name;
    private String sex;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    
    
}

不采用注解的方式。

package com.bxw.entity;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Teacher {
    private int id;
    private String title;
    private String sex;
    
    @Id
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    
    
}

采用注解的方式。

配置文件：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 package="com.bxw.entity">  
   <class name="Student">  
      <id name="id"></id> 
      <property name="name"></property>  
      <property name="sex"></property>  
   </class>
</hibernate-mapping>  

---

Test:


package com.bxw.test;

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

import com.bxw.entity.Student;

public class StudentTest {
    public static void main(String[] args) {
        Student ss = new Student();
        ss.setId(1);
        ss.setName("Han meimei");
        ss.setSex("女");
        
        Configuration conf = new Configuration();
        conf.configure();//不指定路径默认访问classpath下的hibernate.cfg.xml
        Session session = conf.buildSessionFactory().openSession();
        session.beginTransaction();
        session.save(ss);
        session.getTransaction().commit();
        session.close();
    }
}

需要初始化一个读取配置文件的Configuration。

conf.configure()初始化该配置文件，如果不指定路径，则默认该配置文件再classPath下。拿到sessionFactory，拿到session，打开事务，持久化对象，提交事务，关闭事务。

p.s.读取的配置文件是：

<?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>      
              <!-- 连接数据库 -->
              <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver </property>   
            <property name="hibernate.connection.url">jdbc:mysql://localhost/hibernate </property>   
              <property name="hibernate.connection.username">root </property>   
             <property name="hibernate.connection.password">root </property>          
                <!-- DB Dialog -->
            <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect </property>   
                <!-- showSql -->
            <property name="hibernate.show_sql">true </property>
            
            <!-- mapping -->
              <mapping resource="com/bxw/entity/Student.hbm.xml"></mapping>
             <!-- annotation mapping-->
             <mapping class="com.bxw.entity.Teacher"></mapping>
      </session-factory>
    </hibernate-configuration>

==========================分割线==========================

采用注解的方式：
entity:

package com.bxw.entity;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Teacher {
    private int id;
    private String title;
    private String sex;
    
    @Id
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    
    
}

需要再hibernate.cfg.xml中配置相关项。

补：

如果类名与表名不一样，注解方式在@Entity与类名之间添加@Table(name="xxx")，xml方式在<class name="xxx">中添加属性name="xxx"。

注解方式中属性的注解默认为@Basic

如果属性与字段名不同，注解方式添加注解@Column(name="xxx"),xml方式在<property name="xxx">中添加属性column="xxx"

如果属性中有属性不想存在数据库中，使用@Transient

如果属性中存在时间类型，默认保存时间+日期。采用@Temporal(TemporalType.Date)只保存日期，@Temporal(TemporalType.Time)只保存时间

如果属性中存在枚举类型，使用@Enumerated(EnumType.String)注解，xml会很麻烦。@Enumerated(EnumType.ordinal)会存枚举的下标