一个利用模板做输出缓冲+数据库随即抽取显示的例子_PHP

//这是一个简单的缓存例子:

//在本页面中需要随即从几个表中抽取N条记录显示, 因为对数据库操作频繁,

//所以采用缓存方法, 24小时内保持不变, 超过则重新生成.

//本例子还借用了模板的功能来生成页面.

//本文有两种随即产生记录的方法, 分别适应索引Id连续和不连续两种情况,

//仅供参考, 具体情况请具体分析.

//steeven@kali.com.cn



//缓存文件名:

$cache_file = 'index.inc';



if (time()-filemtime($cache_file) 3600*24){

    //如果缓存文件的修改时间没超过24小时

    include ($cache_file);

    exit;

}



//home page of learn

require "../lib/template.php";

require "../lib/common.php";

require "../lib/config.php";

//require "common.php";

//require "config.php";



$IllnessCount = 5;

$AssayCount = 5;

$RadiologyCount =5;



$IllnessList = &get_rand_field('Illness','Name',$IllnessCount);

$AssayList = &get_rand_field('Assay','Name',$AssayCount);

$RadiologyList = &get_rand_field('Radiology','Name',$RadiologyCount);





function &get_rand_field($table,$field,$n){

//$table is identified by Id

    $q = "select count(*) from $table";

    $total = mysql_result(mysql_query($q),0,0);

    $n = min($total,$n);



//如果数据的主索引按Id连续:

    $id_list=array();

    while (sizeof($id_list)$n){

        mt_srand ((double) microtime() * 1000000);   

        $rand = mt_rand(0,$total-1);

        if (in_array($rand,$id_list))

            continue;

        $id_list[] = $rand;

    }

    $q = "select Id,$field from $table where Id in(".implode($id_list,',').")";

    $r = mysql_query($q) or error_die("查询出错");

    return $r;



/* 如果主索引Id非连续: (中间记录可能被删除过)

    for ($i=0; $i
        $id_lists= implode($id_list,',');

        mt_srand ((double) microtime() * 1000000);   

        $rand = mt_rand(0,$total-1);

        $q = "select Id,$field from $table ";

        if ($id_lists != ')

            $q .= "where Id not in($id_lists) ";

        $q .= "limit $rand,1";

        $r = mysql_query($q) or error_die("查询出错");

        $id_list[] = mysql_result($r,0,0);

        mysql_data_seek($r,0);

        $r_list[] = mysql_fetch_object($r);

        $total--;

    }

    return $r_list;

*/

}



//output to html

$t = new Template(".", "keep");

$t->set_file(array("page" => "index.ihtml"));



$t->set_var(array(

    "EmptyBlock" => " "

    ));



$t->set_block("page", "Loop_Illness", "a");

foreach($IllnessList as $row) {

    $t->set_var(array(

        "RandIllness" => html_echo($row->Name),

        "IllnessId" => $row->Id,

        ));

    $t->parse("a", "Loop_Illness", true);

}

if (sizeof($IllnessList)==0)

    $t->parse("a", "EmptyBlock", true);



$t->set_block("page", "Loop_Assay", "loop_assay");

foreach($AssayList as $row) {

    $t->set_var(array(

        "RandAssay" => html_echo($row->Name),

        "AssayId" => $row->Id,

        ));

    $t->parse("loop_assay", "Loop_Assay", true);

}

if (sizeof($AssayList)==0)

    $t->parse("loop_assay", "EmptyBlock", true);



$t->set_block("page", "Loop_Radiology", "loop_radiology");

foreach($RadiologyList as $row) {

    $t->set_var(array(

        "RandRadiology" => html_echo($row->Name),

        "RadiologyId" => $row->Id,

        ));

    $t->parse("loop_radiology", "Loop_Radiology", true);

}

if (sizeof($RadiologyList)==0)

    $t->parse("loop_radiology", "EmptyBlock", true);



//输出新生成的页面

$t->pparse("out", array("page"));



//保存缓冲页面

$fp = fopen($cache_file,'w');

fputs($fp,$t->subst("out"));

fclose($fp);

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