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使用递归算法结合数据库解析成Java树形结构的代码解析
类别:Java编程   作者:码皇   来源:互联网   点击:

这篇文章主要介绍了使用递归算法结合数据库解析成Java树形结构的代码解析的相关资料,需要的朋友可以参考下

1、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 {
    @Testpublic 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}

总结

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