PHP网站安装程序制作的原理、步骤、注意事项和示例代码

<?php 
$files="data/config.php"; 
if(!is_writable($files)){ 
echo "<font color=red>不可写！！！</font>"; 
}else{ 
echo "<font color=green>可写</font>"; 
} 
if(isset($_POST[install])){ 
$config_str = "<?php"; 
$config_str .= "\n"; 
$config_str .= '$mysql_host = "' . $_POST[db_host] . '";'; 
$config_str .= "\n"; 
$config_str .= '$mysql_user = "' . $_POST[db_user] . '";'; 
$config_str .= "\n"; 
$config_str .= '$mysql_pass = "' . $_POST[db_pass] . '";'; 
$config_str .= "\n"; 
$config_str .= '$mysql_dbname = "' . $_POST[db_dbname] . '";'; 
$config_str .= "\n"; 
$config_str .= '$mysql_tag = "' . $_POST[db_tag] . '";'; 
$config_str .= "\n"; 
$config_str .= '?>'; 
$ff = fopen($files, "w+"); 
fwrite($ff, $config_str); 
//===================== 
include_once ("data/config.php"); //嵌入配置文件 
if (!@$link = mysql_connect($mysql_host, $mysql_user, $mysql_pass)) { //检查数据库连接情况 
echo "数据库连接失败! 请返回上一页检查连接参数 <a href=install.php>返回修改</a>"; 
} else { 
mysql_query("CREATE DATABASE `$mysql_dbname`"); 
mysql_select_db($mysql_dbname); 
$sql_query[] = "CREATE TABLE `" . $mysql_tag . "admin_log1` ( 
`id` int(8) unsigned NOT NULL auto_increment, 
`username` varchar(40) NOT NULL COMMENT '操作用户名称', 
`types` varchar(60) NOT NULL, 
PRIMARY KEY (`id`) 
) ;"; 
$sql_query[] = "CREATE TABLE `" . $mysql_tag . "admin_log2` ( 
`id` int(8) unsigned NOT NULL auto_increment, 
`username` varchar(40) NOT NULL COMMENT '操作用户名称', 
`types` varchar(60) NOT NULL, 
PRIMARY KEY (`id`) 
) ;"; 
$sql_query[] = "CREATE TABLE `" . $mysql_tag . "admin_log3` ( 
`id` int(8) unsigned NOT NULL auto_increment, 
`username` varchar(40) NOT NULL COMMENT '操作用户名称', 
`types` varchar(60) NOT NULL, 
PRIMARY KEY (`id`) 
) ;"; 
foreach($sql_query as $val){ 
mysql_query($val); 
} 
echo "<script>alert('安装成功!');location.href='index.php'</script>"; 
rename("install.php","install.lock"); 
} 
} 
?> 
<hr size=1> 
<form action="" method="POST"> 
填写主机：<input type="text" name="db_host" value=""/><br> 
用 户 名：<input type="text" name="db_user" value="root"/><br> 
密　　码：<input type="text" name="db_pass" value=""/><br> 
数据库名：<input type="text" name="db_dbname" value="php100_db"/><br> 
数据前缀：<input type="text" name="db_tag" value="p_"/><br> 
<button type=submit name=install>下一步</button> 
</form>