一个利用模板做输出缓冲+数据库随即抽取显示的例子

<?php
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//这是一个简单的缓存例子:
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//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,
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//所以采用缓存方法, 24小时内保持不变, 超过则重新生成.
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//本例子还借用了模板的功能来生成页面.
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//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,
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//仅供参考, 具体情况请具体分析.
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//[email protected]
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//缓存文件名:
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$cache_file = 'index.inc';
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if (time()-filemtime($cache_file) <3600*24){
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//如果缓存文件的修改时间没超过24小时
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include ($cache_file);
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exit;
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}
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c hina it power . c omsIwzv54GIXFTfltxF8dLUO7Ex
//home page of learn
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require "../lib/template.php";
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require "../lib/common.php";
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require "../lib/config.php";
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//require "common.php";
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//require "config.php";
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$IllnessCount = 5;
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$AssayCount = 5;
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$RadiologyCount =5;
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$IllnessList = &get_rand_field('Illness','Name',$IllnessCount);
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$AssayList = &get_rand_field('Assay','Name',$AssayCount);
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$RadiologyList = &get_rand_field('Radiology','Name',$RadiologyCount);
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function &get_rand_field($table,$field,$n){
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//$table is identified by Id
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$q = "select count(*) from $table";
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$total = mysql_result(mysql_query($q),0,0);
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$n = min($total,$n);
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//如果数据的主索引按Id连续:
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$id_list=array();
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while (sizeof($id_list)<$n){
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mt_srand ((double) microtime() * 1000000);   
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$rand = mt_rand(0,$total-1);
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if (in_array($rand,$id_list))
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continue;
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$id_list[] = $rand;
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}
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$q = "select Id,$field from $table where Id in(".implode($id_list,',').")";
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$r = mysql_query($q) or error_die("查询出错");
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return $r;
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/* 如果主索引Id非连续: (中间记录可能被删除过)
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for ($i=0; $i<$n; $i++){
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$id_lists= implode($id_list,',');
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mt_srand ((double) microtime() * 1000000);   
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$rand = mt_rand(0,$total-1);
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$q = "select Id,$field from $table ";
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if ($id_lists != '')
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$q .= "where Id not in($id_lists) ";
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$q .= "limit $rand,1";
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$r = mysql_query($q) or error_die("查询出错");
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$id_list[] = mysql_result($r,0,0);
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mysql_data_seek($r,0);
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$r_list[] = mysql_fetch_object($r);
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$total--;
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}
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return $r_list;
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*/
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}
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//output to html
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$t = new Template(".", "keep");
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$t->set_file(array("page" => "index.ihtml"));
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$t->set_var(array(
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"EmptyBlock" => " "
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));
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$t->set_block("page", "Loop_Illness", "a");
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foreach($IllnessList as $row) {
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$t->set_var(array(
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"RandIllness" => html_echo($row->Name),
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"IllnessId" => $row->Id,
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));
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$t->parse("a", "Loop_Illness", true);
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}
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if (sizeof($IllnessList)==0)
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$t->parse("a", "EmptyBlock", true);
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$t->set_block("page", "Loop_Assay", "loop_assay");
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foreach($AssayList as $row) {
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$t->set_var(array(
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"RandAssay" => html_echo($row->Name),
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"AssayId" => $row->Id,
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));
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$t->parse("loop_assay", "Loop_Assay", true);
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}
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if (sizeof($AssayList)==0)
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$t->parse("loop_assay", "EmptyBlock", true);
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$t->set_block("page", "Loop_Radiology", "loop_radiology");
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foreach($RadiologyList as $row) {
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$t->set_var(array(
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"RandRadiology" => html_echo($row->Name),
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"RadiologyId" => $row->Id,
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));
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$t->parse("loop_radiology", "Loop_Radiology", true);
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}
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if (sizeof($RadiologyList)==0)
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$t->parse("loop_radiology", "EmptyBlock", true);
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//输出新生成的页面
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$t->pparse("out", array("page"));
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//保存缓冲页面
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$fp = fopen($cache_file,'w');
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fputs($fp,$t->subst("out"));
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fclose($fp);
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?>
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