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JPA学习笔记四[JPQL] 

2011-04-27 10:24:13|  分类： 默认分类 |  标签： |字号大中小订阅

 

 

package org.itfuture.examples.domain;

 

import java.util.HashSet;

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.Table;

 

@Entity

@Table(name = "orders")

public class Order {

       private Integer orderId;

       private Float amount = 0f;

       private Set<OrderItem> items = new HashSet<OrderItem>();

 

       @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(cascade = { CascadeType.REFRESH, CascadeType.PERSIST,

                     CascadeType.MERGE, CascadeType.REMOVE }, fetch = FetchType.LAZY , mappedBy="order")

// many 的一方不会被立即加载，oeder参考方是orderItem 的oeder 属性，它自己不维护这个属性

       public Set<OrderItem> getItems() {

              return items;

       }

 

       public void setItems(Set<OrderItem> items) {

              this.items = items;

       }

 

}

package org.itfuture.examples.domain;

 

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;

 

@Entity

@Table(name="order_items")

public class OrderItem {

       private Integer id;

       private String productName;

       private Float sellPrice = 0f;

       private Order order;

 

       @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 getSellPrice() {

              return sellPrice;

       }

 

       public void setSellPrice(Float sellPrice) {

              this.sellPrice = sellPrice;

       }

 

       @ManyToOne(cascade={CascadeType.REFRESH} , optional=false)

       @JoinColumn(name="orderId")// optional 是否是可选的，orderId对应数据库oeders

//的一个字段

       public Order getOrder() {

              return order;

       }

 

       public void setOrder(Order order) {

              this.order = order;

       }

}

2.5.2        一对一双向映射

package org.itfuture.examples.domain;

 

import javax.persistence.CascadeType;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.OneToOne;

import javax.persistence.PrimaryKeyJoinColumn;

import javax.persistence.Table;

@Entity

@Table(name="persons")

public class Person {

      

       private Integer id;

      

       private String name;

      

       private IdCard idCard;

 

       @Id

       //@GeneratedValue

       public Integer getId() {

              return id;

       }

 

       public void setId(Integer id) {

              this.id = id;

       }

 

       public String getName() {

              return name;

       }

 

       public void setName(String name) {

              this.name = name;

       }

//方案一 ：绿色

       //@OneToOne(cascade=CascadeType.ALL , optional=false)

       //@JoinColumn(name="idcardId" , unique=true)

//方案二： 黄色 //共享主键

       @OneToOne(cascade=CascadeType.ALL)

       @PrimaryKeyJoinColumn

       public IdCard getIdCard() {

              return idCard;

       }

 

       public void setIdCard(IdCard idCard) {

              this.idCard = idCard;

       }

 

}

package org.itfuture.examples.domain;

 

import javax.persistence.CascadeType;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.OneToOne;

import javax.persistence.Table;

 

@Entity

@Table(name="idcards")

public class IdCard {

   

      

       private Integer id;

       private String cardNo;

       private Person person;

 

       @Id

       @GeneratedValue

       public Integer getId() {

              return id;

       }

 

       public void setId(Integer id) {

              this.id = id;

       }

 

       public String getCardNo() {

              return cardNo;

       }

 

       public void setCardNo(String cardNo) {

              this.cardNo = cardNo;

       }

 

       @OneToOne(cascade = { CascadeType.MERGE, CascadeType.PERSIST,

       CascadeType.REFRESH } , mappedBy="idCard" )

       public Person getPerson() {

              return person;

       }

 

       public void setPerson(Person person) {

              this.person = person;

       }

 

}

地址：http://blog.163.com/nyl5566@yeah/blog/static/63162237201132710241399/

 

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