如何在hibernate/jpa中保存一对多？答案

【问题标题】：How to save one-to-many in hibernate/jpa?如何在hibernate/jpa中保存一对多？
【发布时间】：2015-01-30 02:27:09
【问题描述】：

不确定我是否正确描述了与 JPA 的一对多关系。我有 3 张桌子： Handyman 表包含姓名、地址、电话号码等。公司表有：公司名称、地址、电话号码等。 WorkOrder 表：workOrder 编号，工地地址，FK 为勤杂工 ID，FK 为公司 ID。添加新工单时，我使用 select 从数据库中选择公司和勤杂工姓名，然后填写工单。问题是现在怎么保存？

Handyman.java

  @OneToMany(cascade=CascadeType.ALL)
@JoinColumn(name="Handymans_list_id")
private Set<WorkOrder> workOrders;
public Set<WorkOrder> getWorkOrders() {
    return workOrders;
}
public void setWorkOrders(Set<WorkOrder> workOrders) {
    this.workOrders = workOrders;
}

Company.java

    @OneToMany(cascade=CascadeType.ALL)
@JoinColumn(name="Companys_list_id")
private Set<WorkOrder> workOrders;
public Set<WorkOrder> getWorkOrders() {
    return workOrders;
}
public void setWorkOrders(Set<WorkOrder> workOrders) {
    this.workOrders = workOrders;
}

WorkOrder.java

    @ManyToOne(optional=false)
@JoinColumn(name="Companys_list_id", referencedColumnName="id")
//@ManyToOne  
//@JoinColumn(name = "Companys_list_id")
private Company company;

@ManyToOne(optional=false)
@JoinColumn(name="Handymans_list_id", referencedColumnName="id")

//@ManyToOne  
//@JoinColumn(name = "Handymans_list_id") 
private Handyman handyman;

WorkOrderDAOHibernate.java

    public WorkOrder saveWorkOrder(WorkOrder workOrder)
{
    System.out.println("Open session for saving work order ...");
    SessionFactory sf = HibernateUtil.getSessionFactory();
    Session session =  sf.openSession();
    Transaction trans = session.beginTransaction();
    //Integer id = (Integer) session.save(workOrder);
    //Company company = workOrder.getCompany();
    //Handyman handyman = new Handyman();
    //String name  = handyman.getHandymanName();
    //System.out.println("Printing company =" + company);
    //System.out.println("Printing handyman = "+ handyman);
    //System.out.println("Handymans name = " + name);

    //

    //workOrder.setCompany(company);

    //workOrder.setHandyman(handyman);
    System.out.println("Workorder "+workOrder);
    Integer id = (Integer) session.save(workOrder);

    trans.commit();
    workOrder.setId(id);
    session.close();
    return workOrder;

}

workorder3.jsp

    <s:form action="resultAction1" namespace="/">

        <s:actionerror/>
        <s:textfield name="workOrder.workOrder"      label="Work order number" />
        <s:textfield name="workOrder.address"        label="Adress/Location" />
        <s:textfield name="workOrder.email"          label="Email" />
        <s:textfield name="workOrder.comment"        label="Comment" />
        <s:textfield name="workOrder.dateReceived"   label="Date receved" />
        <s:textfield name="workOrder.price"          label="Price" />

<h4>
<s:select label="Pick the company name " 
    headerKey="-1" headerValue="Select Company name"
    list="companyList" 
    name="yourCompanyList" 
     />
</h4> 

<h4>
<s:select label="Pick handyman name " 
    headerKey="-1" headerValue="Select Handyman name"
    list="handymanList" 
    name="yourHandymanList" 
     />
</h4> 


        <s:submit value="submit" name="submit" />

【问题讨论】：

标签： java hibernate jsp

【解决方案1】：

您正试图通过在 HandyMan 和 Company 中放置对 WorkOrder 的引用来定义双向关系。在双向关系中，只有一方是关系的所有者。所有者方将具有 @JoinColumn 注释，而另一方将仅在 @OneToMany 中有一个 mappedBy 属性，它引用映射 @JoinColumn 的 bean 属性。

所以你的类映射如下：

Handyman.java

@OneToMany(cascade=CascadeType.ALL,mappedBy="handyman")
private Set<WorkOrder> workOrders;

Company.java

@OneToMany(cascade=CascadeType.ALL,mappedBy="company")
private Set<WorkOrder> workOrders;

而在 WorkOrder.java

@ManyToOne(optional=false)
@JoinColumn(name="Companys_list_id", referencedColumnName="id")
private Company company;

@ManyToOne(optional=false)
@JoinColumn(name="Handymans_list_id", referencedColumnName="id")
private Handyman handyman;

保存时：

HandyMan handyMan = new HandyMan();
handyMan.setId() // Set the selected id.

Company company = new Company();
company.setId() // Set the selected company id.

workOrder.setCompany(company);
workOrder.setHandyMan(handyMan);

// Populate other details of work order and save using hibernate api.

【讨论】：