无限分类树的代码有很多，下面是个示例：

/**

by lenush;

*/

class Tree

{

var $data = array();

var $child = array(-1=>array());

var $layer = array(-1=>-1);

var $parent = array();

function Tree ($value)

{

$this->setNode(0, -1, $value);

} // end func

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

{

$parent = $parent?$parent:0;

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

$this->child[$id] = array();

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

$this->parent[$id] = $parent;

if (!isset($this->layer[$parent]))

{

$this->layer[$id] = 0;

}

else

{

$this->layer[$id] = $this->layer[$parent] + 1;

}

} // end func

function getList (&$tree, $root= 0)

{

foreach ($this->child[$root] as $key=>$id)

{

$tree[] = $id;

if ($this->child[$id]) $this->getList($tree, $id);

}

} // end func

function getValue ($id)

{

return $this->data[$id];

} // end func

function getLayer ($id, $space = false)

{

return $space?str_repeat($space, $this->layer[$id]):$this->layer[$id];

} // end func

function getParent ($id)

{

return $this->parent[$id];

} // end func

function getParents ($id)

{

while ($this->parent[$id] != -1)

{

$id = $parent[$this->layer[$id]] = $this->parent[$id];

}

ksort($parent);

reset($parent);

return $parent;

} // end func

function getChild ($id)

{

return $this->child[$id];

} // end func

function getChilds ($id = 0)

{

$child = array($id);

$this->getList($child, $id);

return $child;

} // end func

} // end class

//new Tree(根目录的名字);

//根目录的ID自动分配为0

$Tree = new 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();

//遍历输出

foreach ($category as $key=>$id)

{

echo $Tree->getLayer($id, '|-').$Tree->getValue($id)."
n";

}

?>

你的需求中需要从xml文件读取组装成菜单，但是不知道你的xml结构，因此提高一个简单的xml解析方法，可以结合上面的程序使用。

$data = implode("",file('menu.xml'));

$parser = xml_parser_create();

xml_parser_set_option($parser, XML_OPTION_SKIP_WHITE, 1);

xml_parse_into_struct($parser, $data, $xml_array, $tags);

xml_parser_free($parser);

$showMe = xmlToArr($xml_array);

echo "

";

print_r ($showMe);

echo "

";

function xmlToArr($xml_array,&$index=0,$start=0){

$num = count($xml_array);

$result = array();

for ($i = $start; $i < $num; $i++){

if ('open' == $xml_array[$i]['type']){

$start = $i+1;

$result[$xml_array[$i]['attributes']['ID']] = xmlToArr($xml_array,$index,$start);

$i = $index;

}else if ('close' == $xml_array[$i]['type']){

$index = $i;

return $result;

}else if ('complete' == $xml_array[$i]['type']){

$result[$xml_array[$i]['attributes']['ID']] = null;

}

}

return $result;

}

?>