1java中的递归算法、准备表结构及对应的表数据
a、表结构：
create table TB_TREE
(
CID NUMBER not null,
CNAME VARCHAR2(50),
PID NUMBER //父节点
)
b、表数据：
insert into tb_tree (CID, CNAME, PID) values (1, \'中国\', 0);
insert into tb_tree (CID, CNAME, PID) values (2, \'北京市\', 1);
insert into tb_tree (CID, CNAME, PID) values (3, \'广东省\', 1);
insert into tb_tree (CID, CNAME, PID) values (4, \'上海市\', 1);
insert into tb_tree (CID, CNAME, PID) values (5, \'广州市\', 3);
insert into tb_tree (CID, CNAME, PID) values (6, \'深圳市\', 3);
insert into tb_tree (CID, CNAME, PID) values (7, \'海珠区\', 5);
insert into tb_tree (CID, CNAME, PID) values (8, \'天河区\', 5);
insert into tb_tree (CID, CNAME, PID) values (9, \'福田区\', 6);
insert into tb_tree (CID, CNAME, PID) values (10, \'南山区\', 6);
insert into tb_tree (CID, CNAME, PID) values (11, \'密云县\', 2);
insert into tb_tree (CID, CNAME, PID) values (12, \'浦东\', 4);
2、TreeNode对象，对应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、测试数据
public class TreeNodeTest {
@Test
public void loadTree() throws Exception{
System.out.println(JsonUtils.javaToJson(recursiveTree(1)));
}
/**
* 递归算法解析成树形结构
*
* @param cid
* @return
* @author jiqinlin
*/
public TreeNode recursiveTree(int cid) {
//根据cid获取节点对象(SELECT * FROM tb_tree t WHERE t.cid=?)
TreeNode node = personService.getreeNode(cid);
//查询cid下的所有子节点(SELECT * FROM tb_tree t WHERE t.pid=?)
List childTreeNodes = personService.queryTreeNode(cid);
//遍历子节点
for(TreeNode child : childTreeNodes){
TreeNode n = recursiveTree(child.getCid()); //递归
node.getNodes().add(n);
}
return node;
}
}
输出的json格式如下：
{
\"cid\": 1,
\"nodes\": [
{
\"cid\": 2,
\"nodes\": [
{
\"cid\": 11,
\"nodes\": [
],
\"cname\": \"密云县\",
\"pid\": 2
}
],
\"cname\": \"北京市\",
\"pid\": 1
},
{
\"cid\": 3,
\"nodes\": [
{
\"cid\": 5,
\"nodes\": [
{
\"cid\": 7,
\"nodes\": [
],
\"cname\": \"海珠区\",
\"pid\": 5
},
{
\"cid\": 8,
\"nodes\": [
],
\"cname\": \"天河区\",
\"pid\": 5
}
],
\"cname\": \"广州市\",
\"pid\": 3
},
{
\"cid\": 6,
\"nodes\": [
{
\"cid\": 9,
\"nodes\": [
],
\"cname\": \"福田区\",
\"pid\": 6
},
{
\"cid\": 10,
\"nodes\": [
],
\"cname\": \"南山区\",
\"pid\": 6
}
],
\"cname\": \"深圳市\",
\"pid\": 3
}
],
\"cname\": \"广东省\",
\"pid\": 1
},
{
\"cid\": 4,
\"nodes\": [
{
\"cid\": 12,
\"nodes\": [
],
\"cname\": \"浦东\",
\"pid\": 4
}
],
\"cname\": \"上海市\",
\"pid\": 1
}
],
\"cname\": \"中国\",
\"pid\": 0
}
