jpa /休眠一对一映射
[英]jpa/hibernate one-to-one mapping
问题描述
package com.sow.dao;
import java.io.Serializable;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
@Entity
@Table(name = "empcre")
public class EmpAuth implements Serializable {
@Id
@GeneratedValue
@Column(name = "id", unique = true, nullable = false)
int id;
@Column(name = "username")
String userName;
@Column(name = "userpwd")
String Pwd;
@OneToOne(mappedBy = "empcre")
@JoinColumn(name = "id")
private EmpDetails empDetails;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPwd() {
return Pwd;
}
public void setPwd(String pwd) {
Pwd = pwd;
}
public EmpDetails getEmpDetails() {
return empDetails;
}
public void setEmpDetails(EmpDetails empDetails) {
this.empDetails = empDetails;
}
}
package com.sow.dao;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;
@Entity
@Table(name = "empdetails")
@GenericGenerator(name = "person-primarykey", strategy = "foreign", parameters = { @Parameter(name = "property", value = "empcre") })
public class EmpDetails {
@Id
@GeneratedValue(generator = "person-primarykey")
// @GenericGenerator(name = "gen", strategy = "foreign", parameters =
// @Parameter(name = "property", value = "empcre"))
@Column(name = "id", unique = true, nullable = false)
int id;
@Column(name = "empname")
String empName;
@Column(name = "address")
String address;
@Column(name = "empsal")
String empSal;
@OneToOne()
@JoinColumn(name = "id")
private EmpAuth empcre;
public EmpAuth getEmpcre() {
return empcre;
}
public void setEmpcre(EmpAuth empcre) {
this.empcre = empcre;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getEmpSal() {
return empSal;
}
public void setEmpSal(String empSal) {
this.empSal = empSal;
}
}
错误
SEVERE: Servlet.service() for servlet [jersey-serlvet] in context with path [/restDemo] threw exception
org.hibernate.id.IdentifierGenerationException: attempted to assign id from null one-to-one property [com.sow.dao.EmpDetails.empcre]
at org.hibernate.id.ForeignGenerator.generate(ForeignGenerator.java:101)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:120)
at org.hibernate.event.internal.DefaultMergeEventListener.saveTransientEntity(DefaultMergeEventListener.java:422)
at org.hibernate.event.internal.DefaultMergeEventListener.mergeTransientEntity(DefaultMergeEventListener.java:342)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:304)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:259)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:86)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:781)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:766)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:770)
at com.sow.UserService.newEmp(UserService.java:100)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185)
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1469)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1400)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1349)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1339)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:744)
我正在尝试使用关联表中的外键单向实现一对一关系。 在插入日期时，它在主键表中插入数据，但在插入上述错误时给出了错误。
2 个解决方案
解决方案1
0 2014-11-11 12:53:03
您正在使用主键作为联接列。
在@OneToOne ， joinColumn是引用关系另一面的列。 由于id是主键列，因此您也不应将其用作外键列（这是引用列的名称，而不是被引用列的名称）。
将joinColumn更改为emp_id （或将其全部删除以获取默认值）。
异常可能是由Hibernate保持关系的方式引起的，通常是先插入关系的两侧，然后进行更新以创建关系。 在这里，此更新将位于主键列上，该列将失败。
解决方案2
0 2014-11-11 12:59:49
即使这两个表具有相同的主键值，即员工ID，也无法通过上述代码插入。 我建议使用以下方式实现这一目标。
select person-primarykey.nextVal from dual;
这将为您提供序列的下一个值，然后进行2个事务以将生成的值作为ID传递到两个表中。
JPA / Hibernate使用共享主键进行单向一对一映射
[英]JPA / Hibernate unidirectional one-to-one mapping with shared primary key
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