HIbernate 一对多双向注解

package cn.hbonetomany;
import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

/**
 * Created by Administrator on 2017-10-9.
 */
/*声明这个类是持久化实体类*/
@Entity ?//指定实体类

@Table(name = "DEPTS")

 //指定表的名称

public class Dept {
 ???@Id //指定主键

 ???/*
 ???* 当前deptno属性紧跟@Id后的属性，为该表的主键
 ???* */
 ???@GeneratedValue

/声明主键生成策略

 ???private Integer deptno;
 ???private String deptname;
 ???/*
 ???* mappedBy=“dept” 根据Emp类找外键的属性
 ???* 只有多的一方有外键，cascade 级联作用只需要操作一张表
 ???* */
 ???@OneToMany(mappedBy = "deptno11",cascade =CascadeType.ALL)

//指定一对多关系//设定级联关系 All 全部，save_update

 ???private Set<Emp> emps= new HashSet<Emp>();

 ???public Set<Emp> getEmps() {
 ???????return emps;
 ???}

 ???public void setEmps(Set<Emp> emps) {
 ???????this.emps = emps;
 ???}

 ???public Integer getDeptno() {
 ???????return deptno;
 ???}

 ???public void setDeptno(Integer deptno) {
 ???????this.deptno = deptno;
 ???}

 ???public String getDeptname() {
 ???????return deptname;
 ???}

 ???public void setDeptname(String deptname) {
 ???????this.deptname = deptname;
 ???}
}

package cn.hbonetomany;
import javax.persistence.*;
/**
 * Created by Administrator on 2017-10-9.
 */
@Entity
@Table(name = "EMPS")
public class Emp {
 ???@Id
 ???@GeneratedValue
 ???private Integer empno;
 ???private String empname;

 ???public Dept getDept() {
 ???????return deptno11;
 ???}

 ???public void setDept(Dept dept) {
 ???????this.deptno11 = dept;
 ???}
 ???@ManyToOne(fetch = FetchType.LAZY)

 ???多的一方最好别设定级联关系

 ???@JoinColumn(name = "deptno")//指定与本类主键所对应的外表的外键

 ???private Dept deptno11;

 ???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;
 ???}
}

主表没有外键，从表有外键一对多就是采取了关联主表外键
Dept植入集合Emp可以说是植入了一个多的一方，Emp只需导入Dept对象属性，也就是双向的一对多

HIbernate 一对多双向注解

原文地址：http://www.cnblogs.com/hualishu/p/7645498.html