本文实例为大家分享了PHP递归实现层级树状展开的主要代码，供大家参考，具体内容如下

效果图：

实现代码：

<?php 

$db = mysql_connect('localhost', 'root', 'root') or die('Can\'t connect to database'); 

mysql_select_db('test') or die('Can\'t find database : test'); 

$result = mysql_query('select id, fid, name from tree'); 

while($arr = mysql_fetch_array($result)){ 

  $data[] = array( 

    'id' => $arr['id'],  

    'fid' => $arr['fid'], 

    'name' => $arr['name'],  

  ); 

} 

// 将数据按照缩进简单排列 见图1 

function data2arr($tree, $rootId = 0, $level = 0) { 

  foreach($tree as $leaf) { 

    if($leaf['fid'] == $rootId) { 

      echo str_repeat('    ', $level) . $leaf['id'] . ' ' . $leaf['name'] . '<br/>'; 

      foreach($tree as $l) { 

        if($l['fid'] == $leaf['id']) { 

          data2arr($tree, $leaf['id'], $level + 1); 

          break; 

        } 

      } 

    } 

  } 

} 

data2arr($data); 

echo '<br/>-----------------------------------------------------------------------<br/>'; 

// 将数据按照所属关系封装 见图2 

function arr2tree($tree, $rootId = 0) { 

  $return = array(); 

  foreach($tree as $leaf) { 

    if($leaf['fid'] == $rootId) { 

      foreach($tree as $subleaf) { 

        if($subleaf['fid'] == $leaf['id']) { 

          $leaf['children'] = arr2tree($tree, $leaf['id']); 

          break; 

        } 

      } 

      $return[] = $leaf; 

    } 

  } 

  return $return; 

} 

$tree = arr2tree($data); 

print_r($tree); 

echo '<br/>-----------------------------------------------------------------------<br/>'; 

// 将数据使用HTML再次展现 见图3 

function tree2html($tree) { 

  echo '<ul>'; 

  foreach($tree as $leaf) { 

    echo '<li>' .$leaf['name']; 

    if(! emptyempty($leaf['children'])) tree2html($leaf['children']); 

    echo '</li>'; 

  } 

  echo '</ul>'; 

} 

tree2html($tree);

以上就是本文的全部内容，希望对大家学习php程序设计有所帮助。