什么mappedBy
地图到?或者,相反,它应该映射到什么?@OneToMany的mappedBy映射到_____
下面地图的headers
字段@Entity
Foo
按照@OneToMany
docs?然后Foo
将是javax.mail.Header
的包装?
package net.bounceme.dur.usenet.model;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.mail.Header;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.persistence.*;
@Entity
public class Articles implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger LOG = Logger.getLogger(Articles.class.getName());
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column
private String subject;
@OneToMany(mappedBy="foo") //a wrapper for Header is needed?
private List<Header> headers = new ArrayList<>();
public Articles() {
}
public Articles(Message message) {
try {
subject = message.getSubject();
} catch (MessagingException ex) {
Logger.getLogger(Articles.class.getName()).log(Level.SEVERE, null, ex);
}
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Articles)) {
return false;
}
Articles other = (Articles) object;
if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
return false;
}
return true;
}
@Override
public String toString() {
return subject;
}
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
}
一丝理解,让我去试试吧:) – Thufir 2012-07-30 09:33:20
好吧,但是我得到'Exception Description:[class net.bounceme.dur.usenet.model.Articles]使用非实体[class javax.mail.Header]作为目标实体的关系属性[字段标题]。“所以我需要重新考虑一个。另外,ManyToMany会想到它,但我不希望数据库中的所有可能的标题 - 但是这是一条路。我认为这回答了这个问题。谢谢 :) – Thufir 2012-07-30 10:07:41