Using recursive algorithm combined with database parsing into Java tree structure of code parsing
- 2020-10-23 20:05:47
- OfStack
1. Prepare table structure and corresponding table data
Table structure:
create table TB_TREE
(
CID NUMBER not null,
CNAME VARCHAR2(50),
PID NUMBER // The parent node
)
b. Table Data:
insert into tb_tree (CID, CNAME, PID) values (1, ' China ', 0);
insert into tb_tree (CID, CNAME, PID) values (2, ' The Beijing municipal ', 1);
insert into tb_tree (CID, CNAME, PID) values (3, ' Guangdong province, ', 1);
insert into tb_tree (CID, CNAME, PID) values (4, ' Shanghai ', 1);
insert into tb_tree (CID, CNAME, PID) values (5, ' guangzhou ', 3);
insert into tb_tree (CID, CNAME, PID) values (6, ' shenzhen ', 3);
insert into tb_tree (CID, CNAME, PID) values (7, ' zhuhai ', 5);
insert into tb_tree (CID, CNAME, PID) values (8, ' The tianhe district ', 5);
insert into tb_tree (CID, CNAME, PID) values (9, ' Futian district ', 6);
insert into tb_tree (CID, CNAME, PID) values (10, ' Nanshan district ', 6);
insert into tb_tree (CID, CNAME, PID) values (11, ' Miyun county ', 2);
insert into tb_tree (CID, CNAME, PID) values (12, ' In the pudong new area ', 4);
2. TreeNode object, corresponding to tb_tree
public class TreeNode implements Serializable {
private Integer cid;
private String cname;
private Integer pid;
private List nodes = new ArrayList();
public TreeNode() {
}
//getter , setter omit
}
3. Test data
public class TreeNodeTest {
@Test
public void loadTree() throws Exception{
System.out.println(JsonUtils.javaToJson(recursiveTree(1)));
}
/**
* The recursive algorithm resolves into a tree structure
*
* @param cid
* @return
* @author jiqinlin
*/
public TreeNode recursiveTree(int cid) {
// According to the cid Get the node object (SELECT * FROM tb_tree t WHERE t.cid=?)
TreeNode node = personService.getreeNode(cid);
// The query cid All of the child nodes below (SELECT * FROM tb_tree t WHERE t.pid=?)
List childTreeNodes = personService.queryTreeNode(cid);
// Traversal of child nodes
for(TreeNode child : childTreeNodes){
TreeNode n = recursiveTree(child.getCid()); // recursive
node.getNodes().add(n);
}
return node;
}
}
The output json format is as follows:
{
"cid": 1,
"nodes": [
{
"cid": 2,
"nodes": [
{
"cid": 11,
"nodes": [
],
"cname": " Miyun county ",
"pid": 2
}
],
"cname": " The Beijing municipal ",
"pid": 1
},
{
"cid": 3,
"nodes": [
{
"cid": 5,
"nodes": [
{
"cid": 7,
"nodes": [
],
"cname": " zhuhai ",
"pid": 5
},
{
"cid": 8,
"nodes": [
],
"cname": " The tianhe district ",
"pid": 5
}
],
"cname": " guangzhou ",
"pid": 3
},
{
"cid": 6,
"nodes": [
{
"cid": 9,
"nodes": [
],
"cname": " Futian district ",
"pid": 6
},
{
"cid": 10,
"nodes": [
],
"cname": " Nanshan district ",
"pid": 6
}
],
"cname": " shenzhen ",
"pid": 3
}
],
"cname": " Guangdong province, ",
"pid": 1
},
{
"cid": 4,
"nodes": [
{
"cid": 12,
"nodes": [
],
"cname": " In the pudong new area ",
"pid": 4
}
],
"cname": " Shanghai ",
"pid": 1
}
],
"cname": " China ",
"pid": 0
}
conclusion