Hibernate OneToMany mappring错误列不能为null-Java 学习之路

我已经 Build 了下面的 Company 和 product 实体之间的OneToMany关系 . 当我尝试保存 company 实例时，会抛出错误 column company cannot be null . company 列有一个约束，它可以't be null. But why it' null吗？我错过了什么？

Product.java

@Entity
@Table(name="product")
public class Product {

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;

@Column(name="name")
private String name;

@ManyToOne
@JoinColumn(name="company")
private Company company;

public Company getCompany() {
    return company;
}

public void setCompany(Company company) {
    this.company = company;
}

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;
}
}

Company.java

@Entity
@Table(name="manufacturer")
public class Company {

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;

@Column(name="name")
private String name;

@OneToMany(cascade=CascadeType.ALL, mappedBy="company")
private List<Product> products;

public List<Product> getProducts() {
    return products;
}

public void setProducts(List<Product> products) {
    this.products = products;
}

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;
}
}

OnlineStore.java

session = sessionFactory.openSession();
        Transaction tx = session.beginTransaction();
        Product shoes = new Product();
        shoes.setName("Shoes");
        Product tshirt = new Product();
        tshirt.setName("T-shirt");
        Product gloves = new Product();
        gloves.setName("Gloves");
        List<Product> products = new ArrayList<>();
        products.add(shoes);
        products.add(tshirt);
        products.add(gloves);
        Company addidas = new Company();
        addidas.setName("Adiddas");
        addidas.setProducts(products);
        session.save(addidas);
        tx.commit();

错误：列'company'不能为null线程“main”中的异常org.hibernate.exception.ConstraintViolationException：无法在org处的org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert（SQLExceptionTypeDelegate.java:59）执行语句 . 位于org.hibernate.engine.jdbc.spi.SqlExceptionHelper的org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert（SqlExceptionHelper.java:111）中的hibernate.exception.internal.StandardSQLExceptionConverter.convert（StandardSQLExceptionConverter.java:42） . 转换（SqlExceptionHelper.java:97）在org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate（ResultSetReturnImpl.java:207）在org.hibernate.dialect.identity.GetGeneratedKeysDelegate.executeAndExtract（GetGeneratedKeysDelegate.java:57）在组织位于org.hibernate.persister.entity.Abstract的org.hibernate.persister.entity.AbstractEntityPersister.insert（AbstractEntityPersister.java:2840）中的.hibernate.id.insert.AbstractReturningDelegate.performInsert（AbstractReturningDelegate.java:42） EntityPersister.insert（AbstractEntityPersister.java:3411）在org.hibernate.action.internal.EntityIdentityInsertAction.execute（EntityIdentityInsertAction.java:81）在org.hibernate.engine.spi.ActionQueue.execute（ActionQueue.java:619）在组织.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction（ActionQueue.java:273）在org.hibernate.engine.spi.ActionQueue.addInsertAction（ActionQueue.java:254）在org.hibernate.engine.spi.ActionQueue.addAction（ActionQueue的.java：299）在org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction（AbstractSaveEventListener.java:318）在org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate（AbstractSaveEventListener.java:275）在org.hibernate.event . internal.AbstractSaveEventListener.performSave（AbstractSaveEventListener.java:182）在org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId（AbstractSaveEventListener.java:113）在org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGenera tedOrRequestedId（DefaultSaveOrUpdateEventListener.java:192）在org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient（DefaultSaveOrUpdateEventListener.java:177）在org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate（DefaultSaveOrUpdateEventListener.java:97）在org.hibernate作为.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate（DefaultSaveOrUpdateEventListener.java:73）org.hibernate.internal.SessionImpl.fireSaveOrUpdate（SessionImpl.java:644）org.hibernate.internal.SessionImpl.saveOrUpdate（SessionImpl.java:636）at at在org.hibernate.engine.internal.Cascade.cascadeAssociation的org.hibernate.engine.internal.Cascade.cascadeToOne（Cascade.java:391）org.hibernate.engine.spi.CascadingActions $ 5.cascade（CascadingActions.java:219）（cascade.java:316）位于org.hibernate的org.hibernate.engine.internal.Cascade.cascadeProperty（Cascade.java:155）的org.hibernate.engine.internal.Cascade.cascadeCollectionElements（Cascade.java:424） . 发动机.internal.Cascade.cascadeCollection（Cascade.java:356）org.hibernate.engine.Cascade.cascadeAssociation（Cascade.java:319）org.hibernate.engine.internal.Cascade.cascadeProperty（Cascade.java:155））org.hibernate.engine.Internal.Cascade.cascade（Cascade.java:104）org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave（AbstractSaveEventListener.java:445）org.hibernate.event.internal.AbstractSaveEventListener . 在org.hibernate的org.hibernate.event.internal.AbstractSaveEventListener.performSave（AbstractSaveEventListener.java：182）org.hibernate的org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId（AbstractSaveEventListener.java:113）的performSaveOrReplicate（AbstractSaveEventListener.java:281） .event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId（DefaultSaveOrUpdateEventListener.java:192）在org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId（DefaultSaveEventListener.java:38）在org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient（DefaultSaveOrUpdateEventListener.java:177）在org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate（DefaultSaveEventListener.java:32）在org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate（ DefaultSaveOrUpdateEventListener.java:73）org.hibernate.internal.SmplionImpl.Fn上的org.hibernate.internal.SmplionImpl.fireSave（SessionImpl.java:675）org.hibernate.internal.SessionImpl.save上的org.hibernate.internal.SessionImpl.save（SessionImpl.java:667）（SessionImpl.java:662）at com.onetomany.model.OnlineStore.main（OnlineStore.java:48）引起：com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException：在sun.reflect中，'company'列不能为null位于sun.reflect.DelegatingConstructorAccessorImpl.newInstance（未知来源）的sun.reflect.NativeConstructorAccessorImpl.newInstance（未知来源）的.NativeConstructorAccessorImpl.newInstance0（本地方法），位于java.lang.reflect.Constructor.newInstan CE（未知源）在com.mysql.jdbc.Util.handleNewInstance（Util.java:425）在com.mysql.jdbc.Util.getInstance（Util.java:408）在com.mysql.jdbc.SQLError.createSQLException（ SQLError.java:935）com.mysql.jdbc.MysqlIO.checkErrorPacket（MysqlIO.java:3970）com.mysql.jdbc.MysqlIO.checkErrorPacket（MysqlIO.java:3906）at com.mysql.jdbc.MysqlIO.sendCommand （MysqlIO.java:2524）在com.mysql.jdbc.MysqlIO.sqlQueryDirect（MysqlIO.java:2677）在com.mysql.jdbc.ConnectionImpl.execSQL（ConnectionImpl.java:2549）在com.mysql.jdbc.PreparedStatement . 在Com.mysql.jdbc.PreparedStatement.executeUpdateInternal（PreparedStatement.java:2073）的com.mysql.jdbc.PreparedStatement.executeUpdateInternal（PreparedStatement.java:2009）com.mysql.jdbc.PreparedStatement上的executeInternal（PreparedStatement.java:1861）位于org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate（ResultSetRet）的com.mysql.jdbc.PreparedStatement.executeUpdate（PreparedStatement.java:1994）中的.executeLargeUpdate（PreparedStatement.java:5098） urnImpl.java:204）......还有41个

Hibernate OneToMany mappring错误列不能为null

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