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。