java 树状数据算法_使用递归算法结合数据库解析成Java树形结构的代码解析
這篇文章主要介紹了使用遞歸算法結合數(shù)據(jù)庫解析成Java樹形結構的代碼解析的相關資料,需要的朋友可以參考下
1、準備表結構及對應的表數(shù)據(jù)
a、表結構：create table TB_TREE
(
CID NUMBER not null,
CNAME VARCHAR2(50),
PID NUMBER //父節(jié)點
)
b、表數(shù)據(jù)：insert into tb_tree (CID, CNAME, PID) values (1, '中國', 0);
insert into tb_tree (CID, CNAME, PID) values (2, '北京市', 1);
insert into tb_tree (CID, CNAME, PID) values (3, '廣東省', 1);
insert into tb_tree (CID, CNAME, PID) values (4, '上海市', 1);
insert into tb_tree (CID, CNAME, PID) values (5, '廣州市', 3);
insert into tb_tree (CID, CNAME, PID) values (6, '深圳市', 3);
insert into tb_tree (CID, CNAME, PID) values (7, '海珠區(qū)', 5);
insert into tb_tree (CID, CNAME, PID) values (8, '天河區(qū)', 5);
insert into tb_tree (CID, CNAME, PID) values (9, '福田區(qū)', 6);
insert into tb_tree (CID, CNAME, PID) values (10, '南山區(qū)', 6);
insert into tb_tree (CID, CNAME, PID) values (11, '密云縣', 2);
insert into tb_tree (CID, CNAME, PID) values (12, '浦東', 4);
2、TreeNode對象，對應tb_treepublic class TreeNode implements Serializable {
private Integer cid;
private String cname;
private Integer pid;
private List nodes = new ArrayList();
public TreeNode() {
}
//getter、setter省略
}
3、測試數(shù)據(jù)public class TreeNodeTest {
@Test
public void loadTree() throws Exception{
System.out.println(JsonUtils.javaToJson(recursiveTree(1)));
}
/**
* 遞歸算法解析成樹形結構
*
* @param cid
* @return
* @author jiqinlin
*/
public TreeNode recursiveTree(int cid) {
//根據(jù)cid獲取節(jié)點對象(SELECT * FROM tb_tree t WHERE t.cid=?)
TreeNode node = personService.getreeNode(cid);
//查詢cid下的所有子節(jié)點(SELECT * FROM tb_tree t WHERE t.pid=?)
List childTreeNodes = personService.queryTreeNode(cid);
//遍歷子節(jié)點
for(TreeNode child : childTreeNodes){
TreeNode n = recursiveTree(child.getCid()); //遞歸
node.getNodes().add(n);
}
return node;
}
}
輸出的json格式如下：{
"cid": 1,
"nodes": [
{
"cid": 2,
"nodes": [
{
"cid": 11,
"nodes": [
],
"cname": "密云縣",
"pid": 2
}
],
"cname": "北京市",
"pid": 1
},
{
"cid": 3,
"nodes": [
{
"cid": 5,
"nodes": [
{
"cid": 7,
"nodes": [
],
"cname": "海珠區(qū)",
"pid": 5
},
{
"cid": 8,
"nodes": [
],
"cname": "天河區(qū)",
"pid": 5
}
],
"cname": "廣州市",
"pid": 3
},
{
"cid": 6,
"nodes": [
{
"cid": 9,
"nodes": [
],
"cname": "福田區(qū)",
"pid": 6
},
{
"cid": 10,
"nodes": [
],
"cname": "南山區(qū)",
"pid": 6
}
],
"cname": "深圳市",
"pid": 3
}
],
"cname": "廣東省",
"pid": 1
},
{
"cid": 4,
"nodes": [
{
"cid": 12,
"nodes": [
],
"cname": "浦東",
"pid": 4
}
],
"cname": "上海市",
"pid": 1
}
],
"cname": "中國",
"pid": 0
}
總結
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