使用遞歸算法結合數據庫解析成java樹形結構

1、準備表結構及對應的表數據
a、表結構：

create table TB_TREE ( CID NUMBER not null, CNAME VARCHAR2(50), PID NUMBER //父節點 )

b、表數據：

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', 5); insert into tb_tree (CID, CNAME, PID) values (8, '天河區', 5); insert into tb_tree (CID, CNAME, PID) values (9, '福田區', 6); insert into tb_tree (CID, CNAME, PID) values (10, '南山區', 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_tree

public 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、測試數據

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cid獲取節點對象(SELECT * FROM tb_tree t WHERE t.cid=?) TreeNode node = personService.getreeNode(cid); //查詢cid下的所有子節點(SELECT * FROM tb_tree t WHERE t.pid=?) List childTreeNodes = personService.queryTreeNode(cid); //遍歷子節點 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","pid": 5},{"cid": 8,"nodes": [],"cname": "天河區","pid": 5}],"cname": "廣州市","pid": 3},{"cid": 6,"nodes": [{"cid": 9,"nodes": [],"cname": "福田區","pid": 6},{"cid": 10,"nodes": [],"cname": "南山區","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 }

轉載于:https://www.cnblogs.com/linjiaxin/p/6617855.html

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