Hibernate 注解一对多，多对一

接着导入—>注解所需要的包 ejb3-persistence.jar、hibernate-annotations.jar、hibernate-commons-annotations.jar

图示：

部门实体类与注解

package bean;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;

@Entity
@Table(name="deptNew")
public class Dept {
	@Id
	@GeneratedValue(strategy=GenerationType.SEQUENCE,generator="seq_dept")
	@SequenceGenerator(name="seq_dept",sequenceName="seq_dept",initialValue=1,allocationSize=1)
	private Integer id;
	
	@Column
	private String deptName;
	
	//添加关系
	@OneToMany
	@Cascade(CascadeType.SAVE_UPDATE)
	@JoinColumn(name="deptid")
	private Set<Emp> emps=new HashSet<Emp>();
	
	public Set<Emp> getEmps() {
		return emps;
	}
	public void setEmps(Set<Emp> emps) {
		this.emps = emps;
	}
	/*
	 * 构造方法
	 * */
	public Dept() {
	}
	public Dept(String deptName) {
		super();
		this.deptName = deptName;
	}
	/*
	 * 封装方法
	 * */
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getDeptName() {
		return deptName;
	}
	public void setDeptName(String deptName) {
		this.deptName = deptName;
	}
}

员工实体类与注解

package bean;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;

@Entity
@Table(name="empNew")
public class Emp {
	
	//员工编号
	@Id
	@GeneratedValue(strategy=GenerationType.SEQUENCE,generator="emp_generator")
	@SequenceGenerator(name="emp_generator",sequenceName="seq_emp",initialValue=1,allocationSize=1)
	private Integer empNo;
	//员工姓名
	@Column
	private String empName;
	
	@ManyToOne()
	@JoinColumn(name="deptid")
	private Dept dept;
	
	public Dept getDept() {
		return dept;
	}
	public void setDept(Dept dept) {
		this.dept = dept;
	}
	/*
	 * 构造方法
	 * */
	public Emp() {
	}
	public Emp(String empName) {
		super();
		this.empName = empName;
	}
	/*
	 * 封装方法
	 * */
	public Integer getEmpNo() {
		return empNo;
	}
	public void setEmpNo(Integer empNo) {
		this.empNo = empNo;
	}
	public String getEmpName() {
		return empName;
	}
	public void setEmpName(String empName) {
		this.empName = empName;
	}
}

hibernate.cfg.xml 的映射是实体类

<?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">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

<session-factory>

	<!-- 数据库URL -->
	<property name="connection.url">
		jdbc:oracle:thin:@localhost:1521:oracle11
	</property>
	<!-- 数据库用户 -->
	<property name="connection.username">A_hr</property>
	<!-- 数据库用户密码 -->
	<property name="connection.password">123456</property>
	<!-- 数据库 JDBC 驱动 -->
	<property name="connection.driver_class">
		oracle.jdbc.driver.OracleDriver
	</property>
	<!-- 是否将运行期生成的 SQL 输出到日志以供调试  -->
	<property name="show_sql">true</property>
	<!-- 每个数据库都有其对应的 Dialect 以匹配其平台特征 -->
	<property name="dialect">
		org.hibernate.dialect.OracleDialect
	</property>
	<property name="hbm2ddl.auto">create</property>
	<mapping class="bean.Emp" />
	<mapping class="bean.Dept" />

</session-factory>

</hibernate-configuration>

进行数据操作

package test;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;

import util.HibernateSessionFactory;
import bean.Dept;
import bean.Emp;

public class TestAnnotation {
	public static void main(String[] args) {
		//addEmp();
		oneToMany();
		//manyToOne();
	}
	private static void oneToMany() {
		Emp emp=new Emp("李四");
		Dept dept=new Dept("财务部");
		dept.getEmps().add(emp);
		Session session=HibernateSessionFactory.getSession();
		Transaction tx=null;
		try {
			tx=session.beginTransaction();
			session.save(dept);
			tx.commit();//隐式调用刷新方法
			System.out.println("保存成功");
		} catch (HibernateException e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateSessionFactory.closeSession();
		}
	}

	private static void manyToOne() {
		Emp emp=new Emp("李四");
		Dept dept=new Dept("财务部");
		emp.setDept(dept);
		Session session=HibernateSessionFactory.getSession();
		Transaction tx=null;
		try {
			tx=session.beginTransaction();
			session.save(emp);
			session.save(dept);
			tx.commit();//隐式调用刷新方法
			System.out.println("保存成功");
		} catch (HibernateException e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateSessionFactory.closeSession();
		}
	}

	private static void addEmp() {
		Emp emp=new Emp("张三");
		Session session=HibernateSessionFactory.getSession();
		Transaction tx=null;
		try {
			tx=session.beginTransaction();
			session.save(emp);
			tx.commit();//隐式调用刷新方法
			System.out.println("保存成功");
		} catch (HibernateException e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateSessionFactory.closeSession();
		}
	}
}

效果图：

 

查询数据的语句

select id, deptname from deptnew;
select empno, empname, deptid from empnew