hibernate 利用注解生成数据库表以及插入数据

由本人在学习中总结出来，若有不妥还望大家留下意见呀~
1.java实体类注解
         @Entity
         @Table(name="Category")
         @Id
         @GeneratedValue  默认为sql语句中的主键自增长
         @ManyToOne(fetch= FetchType.LAZY)  //只生成一条sql语句，简单语句合并
          在hibernate.cfg.xml中配置实体类
             <mapping class="com.sl.entity.Topic" />
          若不适用注解，则配置xml文件，如之前所试的stu.hbm.xml <mapping resource=""/>
2.生成table语句
        新建一个java类，使其根据注解生成sql语句
        //若不是用的注解而是用的xml连接类和表格的，则应为 new Configuration().configure()
       SchemaExport se = new SchemaExport(new AnnotationConfiguration().configure());
      se.setOutputFile("createTable.sql");
       se.create(true, true);
3.生成table数据
    private static SessionFactory sf = (new AnnotationConfiguration().configure()).buildSessionFactory();
    Session session = sf.openSession();
    //开启事务
    session.beginTransaction();
。。。。
    session.save(c);
    session.getTransaction().commit();
    session.close();
具体代码实现：
  1.java注解实体类
package com.sl.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
@Entity
public class Msg {
private int id;

private String count;
/**所属主题*/
private Topic topic;
@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCount() {
return count;
}
public void setCount(String count) {
this.count = count;
}
@ManyToOne
public Topic getTopic() {
return topic;
}
public void setTopic(Topic topic) {
this.topic = topic;
}

}
  2.hibernate.cfg.xml文件
   <mapping class="com.sl.entity.Category" />
  3.生成数据库表的java文件
package test;

import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
public class CreateTable {
// private static SessionFactory sf;
public static void main(String[] args) {
SchemaExport se = new SchemaExport(new AnnotationConfiguration().configure());
se.setOutputFile("createTable.sql");
se.create(true, true);
}
}
  4.数据插入到数据表
package test;

import java.util.Date;

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

import com.sl.entity.Category;
import com.sl.entity.Msg;
import com.sl.entity.Topic;

public class InitTable {
private static SessionFactory sf = (new AnnotationConfiguration().configure()).buildSessionFactory();
public static void main(String[] args) {
Session session = sf.openSession();
//开启事务
session.beginTransaction();
for (int i = 0; i < 10; i++) {
Category c = new Category();
c.setName("bankuai"+i);
session.save(c);
}
for (int i = 0; i < 10; i++) {
Category c = new Category();
c.setId(1);
Topic t = new Topic();
t.setCategory(c);
t.setTitle("theme"+i);
t.setCreateDate(new Date());
session.save(t);
}
for (int i = 0; i < 10; i++) {
Topic t = new Topic();
t.setId(1);
Msg m =new Msg();
m.setTopic(t);
m.setCount("msg"+i);
session.save(m);
}
session.getTransaction().commit();
session.close();
}
}