Question

我正在制作购物篮摇摆应用程序。我有以下两个类和映射文件：

Product.java

public class Product implements java.io.Serializable {
private Integer productID;
private Integer offerID;
private String productName;
private BigDecimal unitPrice;
private static SessionFactory factory;
private Offer offer;
//getters+setters

产品映射文件：

<hibernate-mapping>
<class name="shoppingbasket.Product" table="products">
    <id name="productID" type="java.lang.Integer" access="field">
        <column name="ProductID" />
        <generator class="assigned" />
    </id>
   <many-to-one name="Offer" class="shoppingbasket.Offer" fetch="select">
        <column name="OfferID" not-null="false" />
    </many-to-one>
    <property name="productName" type="java.lang.String" access="field">
        <column name="ProductName" length="40" not-null="true"/>
    </property>
    <property name="unitPrice" type="java.math.BigDecimal" access="field">
        <column name="UnitPrice"/>
    </property>
</class>
</hibernate-mapping>

Offer.java

public class Offer
{
private Integer offerID;
private String offerDescription;
private String shortDescription;
private Integer TFTPOTGroup;
private Double discountPercentage;
private Set<Offer> offer; 
// getters+setters

提供映射文件：

<hibernate-mapping>
<class name="shoppingbasket.Offer" table="offers">
    <id name="offerID" type="java.lang.Integer" access="field">
        <column name="OfferID" />
        <generator class="assigned" />
    </id>
    <property name="offerDescription" type="java.lang.String" access="field">
        <column name="OfferDescription" length="60" not-null="true"/>
    </property>
    <property name="shortDescription" type="java.lang.String" access="field">
        <column name="ShortDescription" length="10" not-null="false"/>
    </property>
    <property name="TFTPOTGroup" type="java.lang.Integer" access="field">
        <column name="TFTPOTGroup" length="4" not-null="false" default="null"/>
    </property>
    <property name="discountPercentage" type="java.lang.Double" access="field">
        <column name="DiscountPercentage"  not-null="false" default="null"/>
    </property>
    <set name="offer" table="products"
            inverse="true" lazy="true" fetch="select">
        <key>
            <column name="OfferID" not-null="true" />
        </key>
        <one-to-many class="shoppingbasket.Product" />
    </set>
</class>

最后是getProducts（）函数

public List<Product> getProducts() {
    factory = (new Configuration()).configure().buildSessionFactory();
    Session session = factory.getCurrentSession();      
    session.beginTransaction();     
    List<Product> products = new ArrayList<Product>();
    Product q = new Product();
    Query query = session.createQuery("select p from Product p JOIN p.Offer where p.Offer = Offer"); 
    List<Product> list =  query.list();
    Iterator<Product> iter = list.iterator();
    while (iter.hasNext()) {
        Product product = iter.next();
        System.out.println(product.toString());
        products.add(product);
    }
    System.out.println(products);
    return products;
   }

我不知道我做错了什么，但查询只返回了16个结果中的11个。它没有返回的结果是productsID in products = null的结果。我已经尝试了查询中where子句的各种变体，但没有成功。

任何帮助将不胜感激。

Answer 1

我一问完这个问题，经过几个小时的搜索，我自己就解决了。我改变时查询返回所有结果：

Query query = session.createQuery("select p from Product p JOIN p.Offer o where p.Offer=o.offerID or p.Offer is null");

为：

Query query = session.createQuery("select p from Product p LEFT OUTER JOIN p.Offer");

Answer 2

I think it's about data type and your join does not work properly. You can use 
int, string ... primitive in hibernate mapping
 EX:

 private int productID;
 ...
  <id name="offerID" type="int" access="field">
   <column name="OfferID" />
  <generator class="assigned" />
  </id>
  <property name="offerDescription" type="string" access="field">
   <column name="OfferDescription" length="60" not-null="true"/>
 </property>

Java hibernate查询没有返回所有结果

2 个答案: