lib_tree.php

  array());
	public $layer = array(-1 => -1);
	public $parent = array();
	public $countid = 0;

	public function __construct() {
	}

	public function setNode($id, $parent, $value) {

		$parent = $parent ? $parent : 0;

		$this->data[$id] = $value;
		$this->child[$parent][] = $id;
		$this->parent[$id] = $parent;

		if (!isset($this->layer[$parent])) {
			$this->layer[$id] = 0;
		} else {
			$this->layer[$id] = $this->layer[$parent] + 1;
		}
	}

	public function getList(&$tree, $root= 0) {
		foreach ($this->child[$root] as $key => $id) {
			$tree[] = $id;
			if (isset($this->child[$id]))
				$this->getList($tree, $id);
		}
	}

	public function getValue($id) {
		return $this->data[$id];
	}

	public function reSetLayer($id) {
		if ($this->parent[$id]) {
			$this->layer[$this->countid] = $this->layer[$this->countid] + 1;
			$this->reSetLayer($this->parent[$id]);
		}
	}

	public function getLayer($id, $space = false) {
		$this->layer[$id] = 0;
		$this->countid = $id;
		$this->reSetLayer($id);
		return $space ? str_repeat($space, $this->layer[$id]) : $this->layer[$id];
	}

	public function getParent($id) {
		return $this->parent[$id];
	}

	public function getParents($id) {
		while ($this->parent[$id] != -1) {
			$id = $parent[$this->layer[$id]] = $this->parent[$id];
		}

		ksort($parent);
		reset($parent);

		return $parent;
	}

	public function getChild($id) {
		return $this->child[$id];
	}

	public function getChilds($id = 0) {
		$child = array();
		$this->getList($child, $id);

		return $child;
	}

}
//new Tree(根目录的名字); 
//根目录的ID自动分配为0 
$Tree = new lib_tree('目录导航'); 

//setNode(目录ID,上级ID，目录名字); 
$Tree->setNode(1, 0, '目录1'); 
$Tree->setNode(2, 1, '目录2'); 
$Tree->setNode(3, 0, '目录3'); 
$Tree->setNode(4, 3, '目录3.1'); 
$Tree->setNode(5, 3, '目录3.2'); 
$Tree->setNode(6, 3, '目录3.3'); 
$Tree->setNode(7, 2, '目录2.1'); 
$Tree->setNode(8, 2, '目录2.2'); 
$Tree->setNode(9, 2, '目录2.3'); 
$Tree->setNode(10, 6, '目录3.3.1'); 
$Tree->setNode(11, 6, '目录3.3.2'); 
$Tree->setNode(12, 6, '目录3.3.3'); 

//getChilds(指定目录ID); 
//取得指定目录下级目录.如果没有指定目录就由根目录开始 
$category = $Tree->getChilds(); 
echo "
";
print_r($category);
//遍历输出 
foreach ($category as $key=>$id) 
{ 
	echo $Tree->getLayer($id, '  ').$Tree->getValue($id)."\n"; 
} 
?>