1、准备表结构及对应的表数据
a、表结构：
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create table TB_TREE
(
CID NUMBER not null,
CNAME VARCHAR2(50),
PID NUMBER //父节点
)
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b、表数据：
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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);
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2、TreeNode对象，对应tb_tree
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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
}
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3、测试数据
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public class TreeNodeTest {
@Test
public void loadTree() throws Exception{
System.out.println(JsonUtils.javaToJson(recursiveTree(1)));
}
/**
*
* @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;
}
}
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输出的json格式如下：
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{
"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
}
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总结
以上所述是小编给大家介绍的使用递归算法结合数据库解析成Java树形结构的代码解析，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！
原文链接：http://www.cnblogs.com/linjiqin/archive/2013/06/21/3148066.html