php实现无限级分类的树形结构
数据结构和方法如下：
$items = array(
1 => array('id' => 1, 'pid' => 0, 'name' => '江西省'),
2 => array('id' => 2, 'pid' => 0, 'name' => '黑龙江省'),
3 => array('id' => 3, 'pid' => 1, 'name' => '南昌市'),
4 => array('id' => 4, 'pid' => 2, 'name' => '哈尔滨市'),
5 => array('id' => 5, 'pid' => 2, 'name' => '鸡西市'),
6 => array('id' => 6, 'pid' => 4, 'name' => '香坊区'),
7 => array('id' => 7, 'pid' => 4, 'name' => '南岗区'),
8 => array('id' => 8, 'pid' => 6, 'name' => '和兴路'),
9 => array('id' => 9, 'pid' => 7, 'name' => '西大直街'),
10 => array('id' => 10, 'pid' => 8, 'name' => '东北林业大学'),
11 => array('id' => 11, 'pid' => 9, 'name' => '哈尔滨工业大学'),
12 => array('id' => 12, 'pid' => 8, 'name' => '哈尔滨师范大学'),
13 => array('id' => 13, 'pid' => 1, 'name' => '赣州市'),
14 => array('id' => 14, 'pid' => 13, 'name' => '赣县'),
15 => array('id' => 15, 'pid' => 13, 'name' => '于都县'),
16 => array('id' => 16, 'pid' => 14, 'name' => '茅店镇'),
17 => array('id' => 17, 'pid' => 14, 'name' => '大田乡'),
18 => array('id' => 18, 'pid' => 16, 'name' => '义源村'),
19 => array('id' => 19, 'pid' => 16, 'name' => '上坝村'),
);
function tree($items){
$tree = array(); //初始化树结构数据
foreach($items as $value){
if(isset($items[$value['pid']])){ //如果当前父级数据存在
$items[$value['pid']]['son'][] = &$items[$value['id']]; //在对应父级元素添加 son 元素数据，添加的数据为当前数据
}else{ //如果当前父级数据不存在
$tree[] = &$items[$value['id']]; //将当前数据添加到树结构数据里
}
}
return $tree;
}
function genTree($items) {
foreach ($items as $item)
$items[$item['pid']]['son'][$item['id']] = &$items[$item['id']]; //与上方法一样，只是键值不一样
return isset($items[0]['son']) ? $items[0]['son'] : array();
}
print_r(tree($items));
print_r(genTree($items));
返回结果如下：
Array
(
[0] => Array
(
[id] => 1
[pid] => 0
[name] => 江西省
[son] => Array
(
[0] => Array
(
[id] => 3
[pid] => 1
[name] => 南昌市
)
[1] => Array
(
[id] => 13
[pid] => 1
[name] => 赣州市
[son] => Array
(
[0] => Array
(
[id] => 14
[pid] => 13
[name] => 赣县
[son] => Array
(
[0] => Array
(
[id] => 16
[pid] => 14
[name] => 茅店镇
[son] => Array
(
[0] => Array
(
[id] => 18
[pid] => 16
[name] => 义源村
)
[1] => Array
(
[id] => 19
[pid] => 16
[name] => 上坝村
)
)
)
[1] => Array
(
[id] => 17
[pid] => 14
[name] => 大田乡
)
)
)
[1] => Array
(
[id] => 15
[pid] => 13
[name] => 于都县
)
)
)
)
)
[1] => Array
(
[id] => 2
[pid] => 0
[name] => 黑龙江省
[son] => Array
(
[0] => Array
(
[id] => 4
[pid] => 2
[name] => 哈尔滨市
[son] => Array
(
[0] => Array
(
[id] => 6
[pid] => 4
[name] => 香坊区
[son] => Array
(
[0] => Array
(
[id] => 8
[pid] => 6
[name] => 和兴路
[son] => Array
(
[0] => Array
(
[id] => 10
[pid] => 8
[name] => 东北林业大学
)
[1] => Array
(
[id] => 12
[pid] => 8
[name] => 哈尔滨师范大学
)
)
)
)
)
[1] => Array
(
[id] => 7
[pid] => 4
[name] => 南岗区
[son] => Array
(
[0] => Array
(
[id] => 9
[pid] => 7
[name] => 西大直街
[son] => Array
(
[0] => Array
(
[id] => 11
[pid] => 9
[name] => 哈尔滨工业大学
)
)
)
)
)
)
)
[1] => Array
(
[id] => 5
[pid] => 2
[name] => 鸡西市
)
)
)
)
Array
(
[1] => Array
(
[id] => 1
[pid] => 0
[name] => 江西省
[son] => Array
(
[3] => Array
(
[id] => 3
[pid] => 1
[name] => 南昌市
)
[13] => Array
(
[id] => 13
[pid] => 1
[name] => 赣州市
[son] => Array
(
[14] => Array
(
[id] => 14
[pid] => 13
[name] => 赣县
[son] => Array
(
[16] => Array
(
[id] => 16
[pid] => 14
[name] => 茅店镇
[son] => Array
(
[18] => Array
(
[id] => 18
[pid] => 16
[name] => 义源村
)
[19] => Array
(
[id] => 19
[pid] => 16
[name] => 上坝村
)
)
)
[17] => Array
(
[id] => 17
[pid] => 14
[name] => 大田乡
)
)
)
[15] => Array
(
[id] => 15
[pid] => 13
[name] => 于都县
)
)
)
)
)
[2] => Array
(
[id] => 2
[pid] => 0
[name] => 黑龙江省
[son] => Array
(
[4] => Array
(
[id] => 4
[pid] => 2
[name] => 哈尔滨市
[son] => Array
(
[6] => Array
(
[id] => 6
[pid] => 4
[name] => 香坊区
[son] => Array
(
[8] => Array
(
[id] => 8
[pid] => 6
[name] => 和兴路
[son] => Array
(
[10] => Array
(
[id] => 10
[pid] => 8
[name] => 东北林业大学
)
[12] => Array
(
[id] => 12
[pid] => 8
[name] => 哈尔滨师范大学
)
)
)
)
)
[7] => Array
(
[id] => 7
[pid] => 4
[name] => 南岗区
[son] => Array
(
[9] => Array
(
[id] => 9
[pid] => 7
[name] => 西大直街
[son] => Array
(
[11] => Array
(
[id] => 11
[pid] => 9
[name] => 哈尔滨工业大学
)
)
)
)
)
)
)
[5] => Array
(
[id] => 5
[pid] => 2
[name] => 鸡西市
)
)
)
)
参考：https://www.cnblogs.com/zzg521/p/6761576.html