java – object不是声明类-Hibernate的实例
作者：互联网
我是HIbernate的新手,正在练习一对多映射的一些例子,但我不知道它为什么会抛出错误.
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>
4)的hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.dilect">org.hibernate.dialect.HSQLDialect</property>
<property name="hibernate.driver.connection_class">org.hsqldb.jdbcDriver</property>
<property name="hibernate.connection.url">jdbc:hsqldb:hsql://localhost/</property>
<property name="hibernate.connection.username">SA</property>
<property name="hibernate.connection.password"></property>
<property name="show_sql">true</property>
<mapping resource="Employee.hbm.xml" />
</session-factory>
</hibernate-configuration>
5)TestApp.java
package com.common.mainapp;
import java.util.HashSet;
import java.util.Set;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import com.common.pojo.Employee;
public class TestApp {
private static SessionFactory factory;
@SuppressWarnings("deprecation")
public static void main(String[] args) {
try
{
factory =new Configuration().configure().buildSessionFactory();
}
catch(HibernateException exception)
{
exception.printStackTrace();
}
TestApp app=new TestApp();
Set certificate =new HashSet();
certificate.add("BE");
certificate.add("MBA");
certificate.add("BCA");
app.addEmployee("Amit",certificate);
Set certificate1 =new HashSet();
certificate1.add("SCJP");
certificate1.add("OCJP");
app.addEmployee("Sunil",certificate1);
}
public void addEmployee(String name,Set certificate)
{
Transaction tx=null;
Session session=factory.openSession();
Integer employeeId =null;
try
{
tx=session.beginTransaction();
Employee employee=new Employee(name);
employee.setCertificate(certificate);
employeeId = (Integer) session.save(employee);
tx.commit();
}
catch(HibernateException exception)
{
if (tx!=null) tx.rollback();
exception.printStackTrace();
}
finally
{
session.close();
}
}
}
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
)
和
CREATE TABLE EMPLOYEE
(
id int IDENTITY,
name varchar(25)
)
但是在跑完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
解决方法:
您已将证书映射为证书对象集：
<set name="certificate" cascade="all">
<key column="id"></key>
<one-to-many class="com.common.pojo.Certificate" />
</set>
但是在你的测试中你将字符串添加到该集合中：
Set certificate =new HashSet();
certificate.add("BE");
certificate.add("MBA");
certificate.add("BCA");
Java的泛型帮助您在编译时识别此类错误,因此更好地指定您使用的集合的元素类型,因此在添加错误的元素类型时会出现编译错误：
private Set<Certificate> certificate;
标签：java,hibernate,hsqldb 来源： https://codeday.me/bug/20190830/1771374.html