学步园

persistence.xml：

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
    http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">
   
 <persistence-unit name="OneToOnePU" transaction-type="JTA">
    <jta-data-source>java:/MySqlDS</jta-data-source>
    <properties><property name="hibernate.hbm2ddl.auto" value="create-drop"/></properties>
 </persistence-unit>
 
</persistence>

以下是Java代码：

Order.java：

package com.cecltd.domain;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Date;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

@SuppressWarnings("serial")
@Entity
@Table(name = "Orders")
public class Order implements Serializable {
	
	private Integer orderid;
	private Float amount;
	private Set orderItems = new HashSet();
	private Date createdate;

	@Id
	@GeneratedValue
	public Integer getOrderid() {
		return orderid;
	}

	public void setOrderid(Integer orderid) {
		this.orderid = orderid;
	}

	public Float getAmount() {
		return amount;
	}

	public void setAmount(Float amount) {
		this.amount = amount;
	}

	@OneToMany(mappedBy = "order", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
	@OrderBy(value = "id ASC")
	public Set getOrderItems() {
		return orderItems;
	}

	public void setOrderItems(Set orderItems) {
		this.orderItems = orderItems;
	}

	@Temporal(value = TemporalType.TIMESTAMP)
	public Date getCreatedate() {
		return createdate;
	}

	public void setCreatedate(Date createdate) {
		this.createdate = createdate;
	}

	public void addOrderItem(OrderItem orderitem) {
		if (!this.orderItems.contains(orderitem)) {
			this.orderItems.add(orderitem);
			orderitem.setOrder(this);
		}
	}

	public void removeOrderItem(OrderItem orderitem) {
		orderitem.setOrder(null);
		this.orderItems.remove(orderitem);
	}
}

OrderItem.java：

package com.cecltd.domain;

import java.io.Serializable;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@SuppressWarnings("serial")
@Entity
@Table(name = "OrderItems")
public class OrderItem implements Serializable {

    private Integer id;
    private String productname;
    private Float price;
    private Order order;
    
    public OrderItem() {
    }
 
    public OrderItem(String productname, Float price) {
        this.productname = productname;
        this.price = price;
    }

    @Id
    @GeneratedValue 
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    } 
    
    public String getProductname() {
        return productname;
    }
    public void setProductname(String productname) {
        this.productname = productname;
    }
    
    public Float getPrice() {
        return price;
    }
    public void setPrice(Float price) {
        this.price = price;
    }
    
    @ManyToOne(cascade=CascadeType.REFRESH,optional=false)
    @JoinColumn(name = "order_id")  
    public Order getOrder() {
        return order;
    }
    public void setOrder(Order order) {        
        this.order = order;
    }
}

OrderDAO.java：

package com.cecltd.ejb3;

import java.util.List;

import com.cecltd.domain.Order;

public interface OrderDAO {
    
    public void insertOrder();
    public Order getOrderByID(Integer orderid);
    public List getAllOrder();
}

OrderDAOBean.java：

package com.cecltd.ejb3.impl;

import java.util.Date;
import java.util.List;

import javax.ejb.Remote;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import com.cecltd.domain.Order;
import com.cecltd.domain.OrderItem;
import com.cecltd.ejb3.OrderDAO;

@Stateless
@Remote ({OrderDAO.class})
public class OrderDAOBean implements OrderDAO {
	
    @PersistenceContext
    protected EntityManager em;
    
    public void insertOrder(){
    	
        Order order = new Order();
        order.setCreatedate(new Date());
        order.addOrderItem(new OrderItem("笔记本电脑", new Float(13200.5)));
        order.addOrderItem(new OrderItem("U盘", new Float(620)));
        order.setAmount(new Float(13200.5+620));
        em.persist(order);
    }

    public Order getOrderByID(Integer orderid) {
    	
       Order order =  em.find(Order.class, orderid);        
       order.getOrderItems().size();
       //因为是延迟加载，通过执行size()这种方式获取订单下的所有订单项
       return order;
    }

    public List getAllOrder() {
    	
        Query query = em.createQuery("select DISTINCT o from Order o inner join fetch o.orderItems order by o.orderid");
        List result = query.getResultList();
        return result;
    }
}

测试代码：

OneToManyClient.java：

package test;

import java.util.Iterator;
import java.util.List;
import java.util.Properties;

import javax.naming.InitialContext;
import javax.naming.NamingException;

import com.cecltd.domain.Order;
import com.cecltd.domain.OrderItem;
import com.cecltd.ejb3.OrderDAO;

public class OneToManyClient {

 public static void main(String[] args) throws NamingException {
  
  Properties props = new Properties();
  props.setProperty("java.naming.factory.initial", "org.jnp.interfaces.NamingContextFactory");
        props.setProperty("java.naming.provider.url", "127.0.0.1:1099");
        props.setProperty("java.naming.factory.url.pkgs", "org.jboss.naming:org.jnp.interfaces");

  InitialContext ctx = new InitialContext(props);
  try {   
   OrderDAO orderdao = (OrderDAO) ctx.lookup("OrderDAOBean/remote");
   orderdao.insertOrder();
   List list = orderdao.getAllOrder();
   if (list!=null){
    for(int k=0; k<list.size();k++){
     Order od = (Order) list.get(k);
     if (od!=null){
      System.out.println("==============订单号："+ od.getOrderid() +"=================");
      Iterator iterator = od.getOrderItems().iterator();
      while (iterator.hasNext()){
        OrderItem SubOrder = (OrderItem) iterator.next();
        System.out.println("订购产品:"+ SubOrder.getProductname());
      }
     }
    }
   }else{
    System.out.println("获取不到订单列表");
   }
  } catch (Exception e) {
   System.out.println(e.getMessage());
  }
 }
}