eclipse + JBoss 5 + EJB3开发指南（12）：使用命名查询执行JPQL

package  entity;

import  java.util.Collection;
import  javax.persistence.CascadeType;
import  javax.persistence.Entity;
import  javax.persistence.FetchType;
import  javax.persistence.GeneratedValue;
import  javax.persistence.GenerationType;
import  javax.persistence.Id;
import  javax.persistence.JoinColumn;
import  javax.persistence.JoinTable;
import  javax.persistence.ManyToMany;
import  javax.persistence.NamedQuery;
import  javax.persistence.OneToMany;
import  javax.persistence.OneToOne;
import  javax.persistence.PrimaryKeyJoinColumn;
import  javax.persistence.Table;

@Entity
@Table(name  =   " t_customers " )
@NamedQuery(name ="MyQuery",query="select c from Customer c where id=:id" )
public   class  Customer
{
     private   int  id;
     private  String name;
     private  Referee referee;
     private  Collection < Order >  orders;
     private  Collection < Address >  addresses;

    @OneToOne(cascade  =  CascadeType.ALL)
    @PrimaryKeyJoinColumn
     public  Referee getReferee()
    {
         return  referee;
    }

     public   void  setReferee(Referee referee)
    {
         this .referee  =  referee;
    }

    @ManyToMany(cascade  =  CascadeType.PERSIST, fetch  =  FetchType.LAZY)
    @JoinTable(name  =   " t_customers_addresses " , 
              joinColumns  =  @JoinColumn(name  =   " customer_id " , referencedColumnName  =   " id " ), 
              inverseJoinColumns  =  @JoinColumn(name  =   " address_id " , referencedColumnName  =   " id " ))
     public  Collection < Address >  getAddresses()
    {
         return  addresses;
    }

     public   void  setAddresses(Collection < Address >  addresses)
    {
         this .addresses  =  addresses;
    }

    @OneToMany(mappedBy  =   " customer " , cascade  =  CascadeType.ALL)
     public  Collection < Order >  getOrders()
    {
         return  orders;
    }

     public   void  setOrders(Collection < Order >  orders)
    {
         this .orders  =  orders;
    }

    @Id
    @GeneratedValue(strategy  =  GenerationType.IDENTITY)
     public   int  getId()
    {
         return  id;
    }

     public   void  setId( int  id)
    {
         this .id  =  id;
    }

     public  String getName()
    {
         return  name;
    }

     public   void  setName(String name)
    {
         this .name  =  name;
    }
}

     private  Customer queryCustomer( int  id)
    {
         return  (Customer) em.createNamedQuery( " MyQuery " ).setParameter( " id " ,  23 )
                .getSingleResult();
    }