1.26 樹狀結構

參考2200——Tree的代碼

1參見代碼

package com.bjsxt.hibernate;


import java.util.HashSet;
import java.util.Set;


import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;


@Entity
public class Org {
private int id;
private String name;
private Set<Org> children = new HashSet<Org>();
private Org parent;
@Id
@GeneratedValue
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;
}
@OneToMany(cascade=CascadeType.ALL, mappedBy="parent")
public Set<Org> getChildren() {
return children;
}
public void setChildren(Set<Org> children) {
this.children = children;
}

@ManyToOne
@JoinColumn(name="parent_id")
public Org getParent() {
return parent;
}
public void setParent(Org parent) {
this.parent = parent;
}
}

2.測試代碼

public class HibernateTreeTest {
private static SessionFactory sessionFactory;

@BeforeClass
public static void beforeClass() {
new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
}
@AfterClass
public static void afterClass() {
sessionFactory.close();
}

@Test
public void testSave() {
Org o = new Org();
o.setName("總公司");
Org o1 = new Org();
o1.setName("分公司1");
Org o2 = new Org();
o2.setName("分公司2");
Org o11 = new Org();
o11.setName("分公司1下部門1");
Org o12 = new Org();
o12.setName("分公司1下部門2");

o.getChildren().add(o1);
o.getChildren().add(o2);
o1.getChildren().add(o11);
o1.getChildren().add(o12);
o11.setParent(o1);
o12.setParent(o1);
o1.setParent(o);
o2.setParent(o);


Session session = sessionFactory.openSession();
session.beginTransaction();
session.save(o);                            遞歸方式進行存儲

session.getTransaction().commit();
session.close();
}
@Test
public void testLoad() {
testSave();
Session session = sessionFactory.openSession();
session.beginTransaction();
Org o = (Org)session.load(Org.class, 1);
print(o, 0);                                                                自己定義的方法：打印本級org的name。         
session.getTransaction().commit();
session.close();

}

該函數採用了遞歸的過程。
private void print(Org o, int level) {
String preStr = "";
for(int i=0; i<level; i++) {
preStr += "----";
}
System.out.println(preStr + o.getName());
for(Org child : o.getChildren()) {
print(child, level+1);
}
}