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我已經修改了谷歌應用程序引擎（Java）附帶的留言板示例，使用某種'自我加入'來包含父子關係。自我加入谷歌應用程序引擎（java）
現在我greeting.java文件看起來像這樣
package guestbook;
import java.util.Date;
import java.util.List;
import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.IdentityType;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.users.User;
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Greeting {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key id;
@Persistent
private User author;
@Persistent
private String content;
@Persistent
private Date date;
@Persistent
private Greeting parent;
@Persistent(mappedBy="parent")
private List<Greeting> children;
public Greeting getParent() {
return parent;
}
public void setParent(Greeting parent) {
this.parent = parent;
}
public List<Greeting> getChildren() {
return children;
}
public void setChildren(List<Greeting> children) {
this.children = children;
}
public Greeting(User author, String content, Date date) {
this.author = author;
this.content = content;
this.date = date;
}
public Key getId() {
return id;
}
public User getAuthor() {
return author;
}
public String getContent() {
return content;
}
public Date getDate() {
return date;
}
public void setAuthor(User author) {
this.author = author;
}
public void setContent(String content) {
this.content = content;
}
public void setDate(Date date) {
this.date = date;
}
}
注意添加了家長和孩子的字段，以及更改主鍵類型com.google.appengine.api.datastore.Key（如如http://code.google.com/appengine/docs/java/datastore/relationships.html#Owned_One_to_Many_Relationships所示）
現在它不會將數據保存到數據存儲區。我不明白爲什麼。我試圖刪除本地數據存儲和索引文件（如網上說的），但它不會工作。沒有例外，沒有。
有人可以查看一下，請大家幫忙