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Hibernate——树状映射
树状映射
假设:
一张表的结构如下:
id | parent_id | name |
公司组织架构即树状映射
范例:
package com.zgy.hibernate.model;
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;
/*
* Org类,表示组织架构的类
*/
@Entity
public class Org {
private int id;//编号
private String name;//名称
private Set<Org> children = new HashSet<Org>();//Org的子类
private Org parent;//Org的父类
@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",fetch=FetchType.EAGER)
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;
}
}
测试:
package com.zgy.hibernate.model;
import java.util.Date;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
public class HibernateTreeTest {
private static SessionFactory sf;
@BeforeClass
public static void beforeClass() {
sf = new AnnotationConfiguration().configure().buildSessionFactory();
}
@AfterClass
public static void afterClass() {
sf.close();
}
@Test
public void testSchemaExport() {
new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);
}
@Test
public void testSave() {
Org o = new Org();
o.setName("总公司");
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下部门1");
Org o12 = new Org();
o12.setName("分公司1下部门2");
o.getChildren().add(o1);
o.getChildren().add(o2);
o1.getChildren().add(o11);
o2.getChildren().add(o12);
o11.setParent(o1);
o12.setParent(o1);
o1.setParent(o);
o2.setParent(o);
Session session = sf.openSession();
session.beginTransaction();
session.save(o);
session.getTransaction().commit();
session.close();
}
@Test
public void testLoad(){
testSave();
Session session = sf.getCurrentSession();
session.beginTransaction();
Org o = (Org)session.load(Org.class, 1);
print(o,0);
session.getTransaction().commit();
}
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);
}
}
public static void main(String[] args) {
beforeClass();
}
}
Hibernate——树状映射