Java 对象不是声明类Hibernate的实例_Java_Hibernate_Hsqldb

Java 对象不是声明类Hibernate的实例

java hibernate

Java 对象不是声明类Hibernate的实例,java,hibernate,hsqldb,Java,Hibernate,Hsqldb,我不熟悉HIbernate，并且在一对多映射上练习了一些示例，但我不明白为什么它会抛出错误 1） Employee.java package com.common.pojo; import java.util.Set; public class Employee { private int id; private String name; private Set certificate; public Employee (){} public Employee(String name)

我不熟悉HIbernate，并且在一对多映射上练习了一些示例，但我不明白为什么它会抛出错误

1） Employee.java

package com.common.pojo;

import java.util.Set;

public class Employee 
{
private int id;
private String name;
private Set certificate;

public Employee (){}

public Employee(String name) {

    this.name = name;

}
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;
}

public Set  getCertificate() {
    return certificate;
}

public void setCertificate(Set  certificate) {
    this.certificate = certificate;
}

}

2） Certificate.java

package com.common.pojo;

public class Certificate 
{
    private int id;
    private String name;

    public Certificate(){}
    public Certificate(String name)
    {
        this.name = name;
    }

    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;
    }
}

3） Employee.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class table="Employee" name="com.common.pojo.Employee">
        <meta attribute="class-description">
            Employee class
        </meta>
        <id name="id" column="id" type="int">
            <generator class="native"></generator>
        </id>
        <property name="name" column="name" type="string"></property>
        <set name="certificate" cascade="all">
            <key column="id"></key>
            <one-to-many class="com.common.pojo.Certificate" />
        </set>
    </class>


    <class table="Certificate" name="com.common.pojo.Certificate">
        <meta attribute="class-description">
            Certificate class
        </meta>
        <id name="id" column="cer_id" type="int">
            <generator class="native"></generator>
        </id>
        <property name="name" column="cer_name" type="string"></property>

    </class>


</hibernate-mapping>

我使用下面的DDL命令创建了表Employee和Certificate

CREATE TABLE CERTIFICATE
(
cer_id int IDENTITY,
cer_name varchar(25),
emp_id int 
)

及

但在运行之后，我得到了以下错误

Hibernate: insert into Employee (id, name) values (default, ?)
apr 14, 2014 6:34:35 EM org.hibernate.property.BasicPropertyAccessor$BasicGetter get
ERROR: HHH000122: IllegalArgumentException in class: com.common.pojo.Certificate, getter method of property: id
org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of com.common.pojo.Certificate.id
    at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:192)
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:346)
    at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4740)
    at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4459)
    at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:243)
    at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:511)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:100)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
    at org.hibernate.internal.SessionImpl.fireSaveOrUpdate(SessionImpl.java:680)
    at org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:672)
    at org.hibernate.engine.spi.CascadingActions$5.cascade(CascadingActions.java:235)
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:352)
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:295)
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161)
    at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:381)
    at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:321)
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:298)
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161)
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:118)
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:460)
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:294)
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:194)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:209)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:194)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:711)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:703)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:698)
    at com.common.mainapp.TestApp.addEmployee(TestApp.java:74)
    at com.common.mainapp.TestApp.main(TestApp.java:52)
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:169)
    ... 32 more

您已将证书映射为一组

Certificate

对象：

   <set name="certificate" cascade="all">
      <key column="id"></key>
      <one-to-many class="com.common.pojo.Certificate" />
   </set>

Java的泛型帮助您在编译时识别此类错误，因此最好指定所使用集合的元素类型，以便在添加错误的元素类型时出现编译错误：

private Set<Certificate> certificate;

私有集证书；
我在一个设置为“nullable=false”的单向hibernate连接中遇到了相同的错误。删除此项后，错误消失了。可能与此特定问题不完全相关，但一定要检查引用抛出错误的实例的任何实体联接

Hibernate: insert into Employee (id, name) values (default, ?) apr 14, 2014 6:34:35 EM org.hibernate.property.BasicPropertyAccessor$BasicGetter get ERROR: HHH000122: IllegalArgumentException in class: com.common.pojo.Certificate, getter method of property: id org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of com.common.pojo.Certificate.id at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:192) at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:346) at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4740) at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4459) at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:243) at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:511) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:100) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90) at org.hibernate.internal.SessionImpl.fireSaveOrUpdate(SessionImpl.java:680) at org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:672) at org.hibernate.engine.spi.CascadingActions$5.cascade(CascadingActions.java:235) at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:352) at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:295) at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161) at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:381) at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:321) at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:298) at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161) at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:118) at org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:460) at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:294) at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:194) at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:209) at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:194) at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90) at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:711) at org.hibernate.internal.SessionImpl.save(SessionImpl.java:703) at org.hibernate.internal.SessionImpl.save(SessionImpl.java:698) at com.common.mainapp.TestApp.addEmployee(TestApp.java:74) at com.common.mainapp.TestApp.main(TestApp.java:52) Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:169) ... 32 more

<set name="certificate" cascade="all"> <key column="id"></key> <one-to-many class="com.common.pojo.Certificate" /> </set>

Set certificate =new HashSet(); certificate.add("BE"); certificate.add("MBA"); certificate.add("BCA");

private Set<Certificate> certificate;