一个利用模板做输出缓冲+数据库随即抽取显示的例子_PHP
时间：2021-07-01 10:21:17
帮助过：11人阅读
//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; $i<$n; $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);
?&
