无限分类与树型论坛的实现方法

作者:admin 日期:2006-07-29

字体大小: 小中大

无限分类与树型论坛的实现方法

―浮点型字段排序法

在此我不想讨论其他实现方法的利与弊。
既然是使用字段排序，那么我们便设一个名为order的字段。问题是，在这里是使用整数还是使用浮点数类型呢？考虑到会有在两个连续order值中间插入新值的可能，自然是需要使用浮点类型了。
建一个menus表，我们还需要以下字段：
id ：类别编号
mainid ：主分类编号，但不作具体分类使用。如果在树型论坛里，它代表的是主题id
parentid ：父类编号
level ：类别级别，作用其实是方便显示的时候作其他处理
info ：类别名称等。
由此可以得到menus的表结构：
CREATE TABLE `menus` (
`id` INT( 10 ) UNSIGNED NOT NULL AUTO_INCREMENT ,
`mainid` INT( 10 ) UNSIGNED NOT NULL ,
`parentid` INT( 10 ) UNSIGNED NOT NULL ,
`order` FLOAT UNSIGNED NOT NULL ,
`level` SMALLINT( 5 ) UNSIGNED NOT NULL ,
`info` VARCHAR( 128 ) NOT NULL ,
INDEX ( `mainid` , `parentid` , `order` , `level` ) ,
UNIQUE (
`id`
)
) TYPE = MYISAM ;

很容易可以看出，输入的时候是如此简单便实现树结构了:
SELECT * FROM `menus` ORDER BY `mainid` ASC, `order` ASC ;
前提是添加类别的时候，order能正确排序。

添加根分类：
很简单,取得上一个主类的mainid，如A_mainid，则新根分类的mainid则为A_mainid + 1。parentid 为 0 ， order 为0， level也为0， info则自行设定。

添加子分类：
核心思想是，取得新增子分类的前一个分类的order以及它后一个分类的order。
取得前一个分类的order是这里的难点，因为涉及到同级与非同级的情况。非同级的情况很简单，新增别类的前一个order其实就是它的父类的order。如果有同级分类，情况就很复杂了，因为它前面的同级分类有可能会拥有子分类，子分类下又可能还会有子分类，如此下来，要取得前一个order就很难了。
解决的办法有两个：
1.取得新增类同级的前一个类别,如类别A的ID，使用递归的方法，直到取得A类别下最后最小分类的order，那便是要新增分类的前一个order了。这种方法的缺点是，如果A类别下有很多子分类，那么递归需要一定的时间。这种方法适用于普通的分类处理，不适用于树型论坛。不过总体来说，因为是添加类别的时候才使用递归，输出类别的时候跟前面一样，效率还是很高的。
2.作一个记录，记录着与A有关联的最后order。于是我们就需要增加一个表，建利关系树。这种关系树做起来很简单。表结构如下：
CREATE TABLE `menu_tree` (
`mainid` int(10) unsigned NOT NULL default '0',
`tree` text NOT NULL,
`order` float unsigned NOT NULL default '0',
KEY `mainid` (`mainid`,`order`),
FULLTEXT KEY `tree` (`tree`)
) TYPE=MyISAM;
(构建方式请看我后面给出的源码)
取得前一个order之后，要取得后一个order就很简单了。取同mainid下大于前一个order的最小order便是了。如果存在后一个order，那么新增order就取前一个order与后一个order的平均值。如果不存在后一个order，那说明新增类别是main下的最小order，取大于前一个order的最小整数就行了。

主要实现方法便如上面说的。





处理方法

PHP代码:--------------------------------------------------------------------------------

<?php
/*
* ID: class FreeRoad
* Author: Joe Teng <Joe_Teng@hotmail.com>
* Notice: Infinite category maker.
*/

$arrDatabase = array
(
    "host" => 'localhost', "user" => 'root', "password" => '123456', "dbname" => 'test'
);

$resDbc = mysql_connect ( $arrDatabase["host"], $arrDatabase["user"], $arrDatabase["password"] );
mysql_select_db( $arrDatabase['dbname'] );

if ( ! class_exists ( "FreeRoad" ))
{
    class FreeRoad
    {
        var $resDbc ;
        var $strDatabase ;
        var $strMenuTable ;
        var $strMenuTreeTable ;

        var $strFiled_id       = 'id' ;
        var $strFiled_mainid   = 'mainid' ;
        var $strFiled_parentid = 'parentid' ;
        var $strFiled_order    = 'order' ;
        var $strFiled_level    = 'level' ;

        function FreeRoad ( $resDbc , $strDatabase , $strMenuTable , $strMenuTreeTable , $arrSetFileds = array() )
        {
            $this->resDbc           = $resDbc ;
            $this->strDatabase      = $strDatabase;
            $this->strMenuTable     = $strMenuTable ;
            $this->strMenuTreeTable = $strMenuTreeTable ;

            if ( sizeof ( $arrSetFileds ) > 0 )
            {
                $this->strFiled_id       = $arrSetFileds['id'] ;
                $this->strFiled_mainid   = $arrSetFileds['mainid'] ;
                $this->strFiled_parentid = $arrSetFileds['parentid'] ;
                $this->strFiled_order    = $arrSetFileds['order'] ;
                $this->strFiled_level    = $arrSetFileds['level'] ;
            }
        }

        function get_new_mainid ()
        {
            mysql_select_db ( $this->strDatabase , $this->resDbc ) ;

            $strQuery  = " SELECT `$this->strFiled_mainid`
                           FROM `$this->strMenuTable`
                           WHERE `$this->strFiled_parentid` = 0
                           ORDER BY `$this->strFiled_id` DESC LIMIT 0 , 1 " ;
            $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
            while ( $arrRow = mysql_fetch_array ( $resResult ) )
            {
                $intLastedMainId = $arrRow[0] ;
            }
            $intLastedMainId = intval ( $intLastedMainId );
            mysql_free_result ( $resResult ) ;
            return $intLastedMainId + 1 ;
        }

        function get_level_lastest_id ( $intParentId )
        {
            mysql_select_db ( $this->strDatabase , $this->resDbc ) ;
            $strQuery  = " SELECT `$this->strFiled_id`
                           FROM `$this->strMenuTable`
                           WHERE `$this->strFiled_parentid` = $intParentId
                           ORDER BY `$this->strFiled_id` DESC LIMIT 0 , 1 " ;
            $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
            while ( $arrRow = mysql_fetch_row ( $resResult ) )
            {
                $intLevelLastestId = $arrRow[0] ;
            }
            mysql_free_result ( $resResult ) ;
            return $intLevelLastestId ;
        }

        function get_level_lastest_order ( $intParentId )
        {
            mysql_select_db ( $this->strDatabase , $this->resDbc ) ;
            $strQuery  = " SELECT `$this->strFiled_order`
                           FROM `$this->strMenuTable`
                           WHERE `$this->strFiled_id` = $intParentId " ;
            $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
            while ( $arrRow = mysql_fetch_row ( $resResult ) )
            {
                $floSelectItemOrder = $arrRow[0] ;
            }
            mysql_free_result ( $resResult ) ;

            $strQuery  = " SELECT `$this->strFiled_order`
                           FROM `$this->strMenuTreeTable`
                           WHERE BINARY ( `tree`) LIKE '%|$intParentId|%'
                           ORDER BY `$this->strFiled_order` DESC LIMIT 0 , 1 " ;
            //echo $strQuery ;
            $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
            while ( $arrRow = mysql_fetch_row ( $resResult ) )
            {
                $floSelectItemLastestOrder = $arrRow[0] ;
            }
            mysql_free_result ( $resResult ) ;
            if ( ! $floSelectItemLastestOrder ) $floSelectItemLastestOrder = $floSelectItemOrder ;
            return $floSelectItemLastestOrder ;
        }

        function get_elements ( $intParentId = 0 )
        {
            mysql_select_db ( $this->strDatabase , $this->resDbc ) ;
            if ( $intParentId == 0 )
            {
                $intMainId = $this->get_new_mainid ( );
                return array ( "mainid" => $intMainId , "order" => 0 , "level" => 0 ) ;
            }

            $strQuery  = " SELECT `$this->strFiled_mainid` , `$this->strFiled_order` , `$this->strFiled_level`
                           FROM `$this->strMenuTable`
                           WHERE `$this->strFiled_id` = $intParentId " ;
            $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
            while ( $arrRow = mysql_fetch_row ( $resResult ) )
            {
                $intMainId   = $arrRow[0] ;
                $floOrder    = $arrRow[1] ;
                $intLevel    = $arrRow[2] ;
            }
            mysql_free_result ( $resResult ) ;

            if ( ! $intMainId ) return false ;

            $intLevelLastestId = $this->get_level_lastest_id ( $intParentId ) ;

            // get pre order
            if ( $intLevelLastestId )
            {
                $floPreOrder = $this->get_level_lastest_order ( $intLevelLastestId );
               // echo $floPreOrder ;exit;
            }
            else
            {
                $floPreOrder = $floOrder ;
            }

            // get next order
            $strQuery = " SELECT `$this->strFiled_order`
                          FROM `$this->strMenuTable`
                          WHERE `$this->strFiled_mainid` = $intMainId AND `$this->strFiled_order` > $floPreOrder
                          ORDER BY `$this->strFiled_order` ASC LIMIT 0 , 1 " ;
            $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
            while ( $arrRow = mysql_fetch_row ( $resResult ) )
            {
                $floNextOrder = $arrRow[0] ;
            }
            mysql_free_result ( $resResult ) ;

            if ( ! $floNextOrder )
            {
                $floNewOrder = floor ( $floPreOrder + 1 ) ;
            }
            else
            {

                $floNewOrder = number_format ( ( $floPreOrder + $floNextOrder ) / 2 , 14 ) ;
            }

            $intNewLevel = $intLevel + 1 ;
            return array ( "mainid" => $intMainId , "order" => $floNewOrder , "level" => $intNewLevel ) ;
        }

        function update_tree ( $intMainId , $intParentId , $floOrder )
        {
            if ( !$intParentId ) return false ;

            mysql_select_db ( $this->strDatabase , $this->resDbc ) ;

            $strQuery  = " SELECT `tree`
                           FROM `$this->strMenuTreeTable`
                           WHERE `mainid` = $intMainId AND BINARY ( `tree`) LIKE '%|$intParentId|'
                           ORDER BY `order` DESC LIMIT 0 , 1 " ;
            $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
            while ( $arrRow = mysql_fetch_row ( $resResult ) )
            {
                $strTree  = $arrRow[0] ;
            }
            mysql_free_result ( $resResult ) ;

            if ( ! $strTree )
            {
                $strQuery  = " SELECT `$this->strFiled_parentid`
                               FROM `$this->strMenuTable`
                               WHERE `$this->strFiled_id` = $intParentId " ;
                $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
                while ( $arrRow = mysql_fetch_row ( $resResult ) )
                {
                    $intPreParentId  = $arrRow[0] ;
                }
                mysql_free_result ( $resResult ) ;

                if ( ! $intPreParentId )
                {
                    $strPreTree = '';
                }
                else
                {
                    $strQuery  = " SELECT `tree`
                                   FROM `$this->strMenuTreeTable`
                                   WHERE `mainid` = $intMainId AND BINARY ( `tree`) LIKE '%|$intPreParentId|'
                                   ORDER BY `order` DESC LIMIT 0 , 1 " ;
                    $resResult = mysql_query ( &$strQuery , $this->resDbc ) ;
                    while ( $arrRow = mysql_fetch_row ( $resResult ) )
                    {
                        $strPreTree  = $arrRow[0] ;
                    }
                    mysql_free_result ( $resResult ) ;
                }

                $strNewTree = $strPreTree . '|'. $intParentId . '|' ;
                $strQuery   = " INSERT INTO `$this->strMenuTreeTable`
                                VALUES ( $intMainId, '$strNewTree', $floOrder ) " ;
                $resResult  = mysql_query ( &$strQuery , $this->resDbc ) ;
                @mysql_free_result ( $resResult ) ;
                return true ;
            }
            else
            {
                $strQuery   = " UPDATE `$this->strMenuTreeTable`
                                SET `order` =  $floOrder
                                WHERE `mainid` = $intMainId AND `tree` = '$strTree' " ;
                $resResult  = mysql_query ( &$strQuery , $this->resDbc ) ;
                @mysql_free_result ( $resResult ) ;
                return true ;
            }
        }
    }
}

/*
$pFreeRoad = new FreeRoad ( $resDbc , $arrDatabase["dbname"] , 'menus' , 'menu_tree' ) ;

$info = 'change here';

$intParentId = change here ;
$arrItems  = $pFreeRoad->get_elements( $intParentId ) ;
$intMainId = $arrItems['mainid'] ;
$floOrder  = $arrItems['order'] ;
$intLevel  = $arrItems['level'] ;

$strQuery  = " INSERT INTO `menus` VALUES ( '' , $intMainId , $intParentId , $floOrder , $intLevel, '$info' ) " ;
$resResult = mysql_query ( &$strQuery , $resDbc ) ;

$pFreeRoad->update_tree ( $intMainId , $intParentId , $floOrder ) ;

@mysql_close( $resDbc ) ;
*/
?>

--------------------------------------------------------------------------------

PHP代码:--------------------------------------------------------------------------------

<?php
include "freeroad.class.php";
$strQuery = " SELECT * FROM `menus` ORDER BY `mainid` ASC , `order` ASC ";
$resResult = mysql_query ( &$strQuery , $resDbc ) ;
while ( $arrRows = mysql_fetch_array ( $resResult ))
{
    $intLevel = $arrRows["level"] ;
    $strSpace = '' ;
    for ( $i = 0 ; $i <= $intLevel ; $i++ )
    {
        $strSpace .= "　　";
    }
    if ( $i>1 )
    {
       $strSpace .= '--';
    }
    echo $strSpace .  $arrRows["id"] . $arrRows["info"] ."<br>";
}

if ( $_GET["action"] == 'add' )
{

    $pFreeRoad = new FreeRoad ( $resDbc , $arrDatabase["dbname"] , 'menus' , 'menu_tree' ) ;

    $info = 'F1';

    $intParentId = 1 ;
    $arrItems  = $pFreeRoad->get_elements( $intParentId ) ;
    $intMainId = $arrItems['mainid'] ;
    $floOrder  = $arrItems['order'] ;
    $intLevel  = $arrItems['level'] ;

    $strQuery  = " INSERT INTO `menus` VALUES ( '' , $intMainId , $intParentId , $floOrder , $intLevel, '$info' ) " ;
    $resResult = mysql_query ( &$strQuery , $resDbc ) ;

    $pFreeRoad->update_tree ( $intMainId , $intParentId , $floOrder ) ;

    @mysql_close( $resDbc ) ;

}
?>