Converts data from a database with a parent-child relationship into JSON format using Java code

Ideas:
① all the parent nodes in the data into a collection
②, fetching all child nodes of the parent node into another collection in the data
③, using the iterative method, iterates through a layer of child nodes
Tool class:
Package com.assasion.test;

Import Net.sf.json.JSONArray;

Import java.util.ArrayList;
Import java.util.List;

public class Treebuilder {


list<companynode> nodes = new arraylist<companynode> ();

Public Treebuilder (list<companynode> nodes) {
Super ();
this.nodes= nodes;
}

/**
* Build JSON tree structure
* @return
*/
Public String Buildjsontree () {
list<companynode> Nodetree = Buildtree ();
Jsonarray Jsonarray = Jsonarray.fromobject (Nodetree);
return jsonarray.tostring ();
}

/**
* Build a tree-shaped structure
* @return
*/
Public list<companynode> Buildtree () {
list<companynode> treenodes = new arraylist<companynode> ();
list<companynode> rootnodes = Getrootnodes ();
for (Companynode rootnode:rootnodes) {
Buildchildnodes (RootNode);
Treenodes.add (RootNode);
}
return treenodes;
}

/**
* Recursive child nodes
* @param node
*/
public void Buildchildnodes (Companynode node) {
list<companynode> children = getchildnodes (node);
if (!children.isempty ()) {
for (Companynode Child:children) {
Buildchildnodes (child);
}
Node.setchild (children);
}
}

/**
* Gets all child nodes under the parent node
* @param pnode
* @return
*/
Public list<companynode> getchildnodes (Companynode pnode) {//Incoming parent node object, if the child node of the parent node is placed in the child node collection
list<companynode> childNodes = new arraylist<companynode> ();
for (Companynode n:nodes) {//filter from nodes so that the child nodes are Pnode
if (PNODE.GETCYBH (). Equals (N.GETSJ_CYBH ())) {
Childnodes.add (n);
}
}
return childNodes;
}

/**
* Determine if the root node
* @param node
* @return
*/
public boolean RootNode (Companynode node) {
Boolean isrootnode = true;
for (Companynode n:nodes) {//filter from nodes so the parent node
if (NODE.GETSJ_CYBH () Equals (N.GETCYBH ())) {//To determine the incoming node object, his superior member number also has no corresponding member number in node, and if not, the root node
Isrootnode= false;
Break
}
}
return isrootnode;
}

/**
* Gets all the root nodes in the collection
* @return
*/
Public list<companynode> Getrootnodes () {
list<companynode> rootnodes = new arraylist<companynode> ();
for (Companynode n:nodes) {
if (RootNode (n)) {
Rootnodes.add (n);//Put the root node into the Rootnodes collection
}
}
return rootnodes;
}
}
Entity class:

Package com.assasion.test;

Import java.util.List;

public class Companynode {
private String name;//Company Name
Private String cybh;//Member number
Private String sj_cybh;//Superior member number
Private list<companynode> child;//Subordinate company

Public Companynode () {
}

Public Companynode (string name, String cybh, String sj_cybh,list<companynode> child) {
THIS.name = name;
THIS.CYBH = CYBH;
THIS.SJ_CYBH = SJ_CYBH;
This.child=child;
}

Public list<companynode> Getchild () {
return child;
}

public void SetChild (List<companynode> child) {
This.child = child;
}

Public String GetName () {
return name;
}

public void SetName (String name) {
THIS.name = name;
}

Public String getcybh () {
return CYBH;
}

public void Setcybh (String cybh) {
THIS.CYBH = CYBH;
}

Public String getsj_cybh () {
return SJ_CYBH;
}

public void Setsj_cybh (String sj_cybh) {
THIS.SJ_CYBH = SJ_CYBH;
}
}

Converts data from a database with a parent-child relationship into JSON format using Java code