树状自关联 hibernate配置，查询

栏目实体
每个栏目有多个子栏目,一个父栏目
一级栏目无父栏目
hibernate配置

package com.france.bean;import java.util.HashSet;
import java.util.Set;import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
import javax.persistence.Table;import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;@Entity
@Table(name = "lanmu")
@DynamicUpdate(true)
@DynamicInsert(true)
public class Lanmu implements java.io.Serializable {/*** 栏目 自关联一对多*/private static final long serialVersionUID = 862821212669955478L;private Integer id;private String name;private String description;private Lanmu parentLanmu;private Integer level;private Set<Lanmu> children = new HashSet<Lanmu>(0);public Lanmu() {}@Id@GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "lanmu_id", unique = true, nullable = false)public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}@ManyToOne(fetch = FetchType.LAZY)@JoinColumn(name = "parentLanmu", nullable = true)public Lanmu getParentLanmu() {return parentLanmu;}public void setParentLanmu(Lanmu parentLanmu) {this.parentLanmu = parentLanmu;}public Integer getLevel() {return level;}public void setLevel(Integer level) {this.level = level;}@OneToMany(targetEntity=Lanmu.class, mappedBy="parentLanmu", cascade=CascadeType.ALL, fetch = FetchType.EAGER)  @OrderBy("name")public Set<Lanmu> getChildren() {return children;}public void setChildren(Set<Lanmu> children) {this.children = children;}}

查询的时候本来是参考
MySQL中进行树状所有子节点的查询
但是hibernate已经在对象映射做好了，所以直接根据id得到Lanu对象就可以

@Overridepublic Lanmu findAllChildrenLanmu(int lanmu_id) {// TODO Auto-generated method stubLanmu root=new Lanmu();root=lanmuDAO.get(Lanmu.class, lanmu_id);return root;}

测试代码：

    @Testpublic void testFindAllChildrenLanmu() {Lanmu root=service.findAllChildrenLanmu(1);System.out.println(root.getParentLanmu());//得到nullSystem.out.println("get root ok");Set<Lanmu> c1=root.getChildren();Iterator iter=c1.iterator();while(iter.hasNext()){Lanmu l= (Lanmu)iter.next();System.out.printf("lanmu_id:%d,lanmu_name:%s\n",l.getId(),l.getName());}}

输出：

Hibernate: selectlanmu0_.lanmu_id as lanmu_id1_7_0_,lanmu0_.description as descript2_7_0_,lanmu0_.level as level3_7_0_,lanmu0_.name as name4_7_0_,lanmu0_.parentLanmu as parentLa5_7_0_,children1_.parentLanmu as parentLa5_7_1_,children1_.lanmu_id as lanmu_id1_7_1_,children1_.lanmu_id as lanmu_id1_7_2_,children1_.description as descript2_7_2_,children1_.level as level3_7_2_,children1_.name as name4_7_2_,children1_.parentLanmu as parentLa5_7_2_ fromlanmu lanmu0_ left outer joinlanmu children1_ on lanmu0_.lanmu_id=children1_.parentLanmu wherelanmu0_.lanmu_id=? order bychildren1_.name//得到二级栏目 一级栏目(1)和二级栏目节点(3,4)Hibernate: selectchildren0_.parentLanmu as parentLa5_7_0_,children0_.lanmu_id as lanmu_id1_7_0_,children0_.lanmu_id as lanmu_id1_7_1_,children0_.description as descript2_7_1_,children0_.level as level3_7_1_,children0_.name as name4_7_1_,children0_.parentLanmu as parentLa5_7_1_ fromlanmu children0_ wherechildren0_.parentLanmu=? order bychildren0_.name//得到三级栏目节点(null)(children0_.parentLanmu=3)
Hibernate: selectchildren0_.parentLanmu as parentLa5_7_0_,children0_.lanmu_id as lanmu_id1_7_0_,children0_.lanmu_id as lanmu_id1_7_1_,children0_.description as descript2_7_1_,children0_.level as level3_7_1_,children0_.name as name4_7_1_,children0_.parentLanmu as parentLa5_7_1_ fromlanmu children0_ wherechildren0_.parentLanmu=? order bychildren0_.name//得到另一个三级栏目节点(5)(children0_.parentLanmu=4)
Hibernate: selectchildren0_.parentLanmu as parentLa5_7_0_,children0_.lanmu_id as lanmu_id1_7_0_,children0_.lanmu_id as lanmu_id1_7_1_,children0_.description as descript2_7_1_,children0_.level as level3_7_1_,children0_.name as name4_7_1_,children0_.parentLanmu as parentLa5_7_1_ fromlanmu children0_ wherechildren0_.parentLanmu=? order bychildren0_.name//得到四级栏目节点（null）(children0_.parentLanmu=5)
null
get root ok
lanmu_id:3,lanmu_name:lanmuAA
lanmu_id:4,lanmu_name:lanmuAB

数据库数据

lanmu_id	description	level	name	parentLanmu
1	NULL	1	lanmuA	NULL
2	NULL	1	lanmuB	NULL
3	NULL	2	lanmuAA	1
4	NULL	2	lanmuAB	1
5	NULL	3	lanmuABA	4

最后，配置的时候注意fetch = FetchType.EAGER 的使用范围即可

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