java 将数据字典（父子结构）绑定成List集合，以实现数据库同步功能
最近公司做了一个项目，其中有一个功能是将本地的数据库同步到远程服务器端，同步的过程不是本文章的重点，重点是在导入的过程中，涉及到一个数据字典类型的表，也就是带有父ID的表，即（父子表），这就对导入提出了新的要求：就是在导入新的表中时，必须先导入父表，再导入子表，如果多级的话，依次从顶级开始向下导入，领导和我说了一顿，什么while循环啊，递归啊，说实话，我知道他要表达的意思，可就是不会写，没办法上网找找，终于我看到了一偏文章：
Kaer_GG的文章，树形list（菜单树）递归遍历list对我帮助很大，好了，不费话，看看我的数据库结构：
package com.ringchi.entity.department;
import com.ringchi.entity.NamedObject;
import com.ringchi.entity.NamedTreeObject;
import com.ringchi.entity.dictionary.Dictionary;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;
@Entity
@Table(name="basic_department")
public class Department extends NamedObject
implements NamedTreeObject
{
private static final long serialVersionUID = 3256440322035822899L;
private String assignedCode;
private String abbreviation;
private Dictionary type;
private Dictionary kind;
private Date createDate;
private Date dropDate;
private int sequence;
private String location;
private Department parent;
private Dictionary level;
private String levelCode;
public Department()
{
}
public Department(String id)
{
super(id);
}
public Department(String id, String name) {
super(id, name);
}
@Column(length=20)
public String getAbbreviation()
{
return this.abbreviation;
}
public void setAbbreviation(String abbreviation)
{
this.abbreviation = abbreviation;
}
@Column(length=20)
public String getAssignedCode() {
return this.assignedCode;
}
public void setAssignedCode(String assignedCode) {
this.assignedCode = assignedCode;
}
@Temporal(TemporalType.DATE)
public Date getCreateDate()
{
return this.createDate;
}
public void setCreateDate(Date createDate)
{
this.createDate = createDate;
}
@ManyToOne
@JoinColumn(name="Type")
public Dictionary getType()
{
return this.type;
}
public void setType(Dictionary type)
{
this.type = type;
}
@Temporal(TemporalType.DATE)
public Date getDropDate()
{
return this.dropDate;
}
public void setDropDate(Date dropDate)
{
this.dropDate = dropDate;
}
public int getSequence()
{
return this.sequence;
}
public void setSequence(int sequence)
{
this.sequence = sequence;
}
@ManyToOne
@JoinColumn(name="Parent")
public Department getParent()
{
return this.parent;
}
public void setParent(Department parent)
{
this.parent = parent;
}
public String toString()
{
String result = getId() + ":" + getName() + "[";
if (getParent() != null) {
result = result + "{" + getParent().getId() + "} ";
}
result = result + "]";
return result;
}
@Transient
public NamedTreeObject getTreeParent() {
return getParent();
}
public void setTreeParent(NamedTreeObject parent) {
setParent((Department)parent);
}
@ManyToOne
@JoinColumn(name="Level")
public Dictionary getLevel() { return this.level; }
public void setLevel(Dictionary level)
{
this.level = level;
}
@ManyToOne
@JoinColumn(name="Kind")
public Dictionary getKind() { return this.kind; }
public void setKind(Dictionary kind)
{
this.kind = kind;
}
@Column(length=100)
public String getLocation() {
return this.location;
}
public void setLocation(String location) {
this.location = location;
}
@Column(length=50)
public String getLevelCode()
{
return this.levelCode;
}
public void setLevelCode(String levelCode) {
this.levelCode = levelCode;
}
}
以上是实体部分，重点来了，如何将这些数据绑定成List集合呢？看代码
//先查找原数据库
List<Department> equips = theDMO.getObjects("FROM Department");
System.out.println("原数据库");
for (Department department : equips) {
System.out.println(department);
}
//我们来看看打印的结果：
可以看到原来的数据库是无序的，此时要是导入的话，肯定出错，下面看具体的转换过程
List<Department> resultList=new ArrayList<Department>();
for (Department department : equips) {
if (department.getParent()==null) {//父级菜单开始添加
resultList.add(department);
if (ifChilds(equips, department.getId())) {//存在子集
List<Department> childs = new ArrayList<>();
childs = getChildList(equips,department.getId(),childs);
resultList.addAll(childs);
}
}
}
//判断是否存在子集
private static boolean ifChilds(List<Department> list,String pId) {
boolean flag = false;
for (Department department : list) {
if (department.getParent()!=null) {
if (department.getParent().getId().equals(pId)) {
flag=true;
break;
}
}
}
return flag;
}
//获取父id下的子集合
private static List<Department> getChildList(List<Department> list,String pId,List<Department> reList) {
for (Department department : list) {
if (department.getParent()!=null) {
if (department.getParent().getId().equals(pId)) {//查询下级菜单
reList.add(department);
if (ifChilds(list, department.getId())) {
getChildList(list, department.getId(), reList);
}
}
}
}
return reList;
}
现在看看转换后的情况吧：
System.out.println(“新数据库”);
for (Department department : resultList) {
if (department.getParent()!=null) {
System.out.println(department.getId()+”\t”+department.getName()+”\t”+department.getParent().getName());
}else {
System.out.println(department.getId()+"\t"+department.getName());
System.out.println("########");
}
}
“`
好了，希望对大家有所帮助，对我自己也是个帮助！
