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 ) |
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 ); |
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 } |
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; } } |
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 } |
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