PHP编程常用技巧四则_PHP
PHP编程常用技巧四则:
1.配置PHP文件目录
作为服务器端解释执行的脚本语言,PHP程序放置在某个服务器可以访问的目录下,一般可以通过修改Apache的httpd.conj进行配置,例如我们在该文件中的一句:
Alias /test/ "d:brhpwebsitebrhp/" 那么在浏览器端输入:“http://localhost/test/+PHP文件名”就可以访问d:brhpwebsitebrhp/下的PHP文件了;可见该行不过是为存放PHP文件的目录起一个别名。
其次,还可以通过指定DocumentRoot路径得到存放服务器文件的目录,在httpd.conj找到以下两行,其中的路径可以随意指定,你的PHP文件也可以放在该目录下,服务器同样可以运行它们,如“http://localhost/+PHP文件名”。
一般的,将PHP文件放在同一个地方比较好,可以方便管理,而其他文件放在另外一个地方。
DocumentRoot "C:/usr/bin/html/"
2.服务器端目录的索引文件
在httpd.conj中,有一行: DirectoryIndex index.html
该行指定目录默认打开文件为index.html,当访问某个目录时,服务器就会自动查找index.html, 若果不存在,则显示目录中的所有文件列表,默认打开文件可以改为别的,如index.php3等等,但是也许我们有很多目录,无论是存放图片,文本等资料的,还是存放PHP文件或别的文件的目录,我们并不希望用户能看到目录中的文件列表,在httpd.conj 中指定了一个.htacess文件,该文件产生一个目录索引文件,例如我们用写字板建立一个.htacess文件:
# .htacess #
DirectoryIndex error_open.php
再建立一个错误警告文件:
# error_open.php #
其中的error_open.php为权限错误警告文件,将此2文件放在所有保护目录下,当用户企图打开目录时,自动转向执行error_open.php,显示错误警告。
3.目录删除巧实现
我们知道,PHP4 for/win32中有个rename()函数可以支持对目录/文件进行重命名,如: rename( oldpath, newpath) // oldpath为文件或目录原来路径; // newpath为新定义路径;
实现将 oldpath改名为 newpath。
PHP4中没有删除目录/文件的函数,怎么作到删除呢?我们知道,php.ini中有一行用来完成HTTP上传操作的临时文件目录配置行: upload_tmp_dir= ;
PHP4支持该临时目录的配置(PHP3不支持),当上载操作完成则自动清空临时目录,好了,用它我们可以巧妙的实现文件/目录的删除,比如设置: upload_tmp_dir="d:brhpwebsitebrhp/tmp/" ; 要删除某个目录 path,执行: tmp="d:brhpwebsitebrhp/tmp/;" rename( path, tmp) ?>;
那么文件或目录 path改名为 tmp后, tmp目录下的所有文件/目录自动清除,就完成了删除操作。
4.快速建立MySql数据库表
PHP和MySql数据库达到了完美结合,在网页上,比如在论坛或书屋发表作品的新用户,我们要把他的言论信息在线写入数据库中,往往要在相应的数据库中为该用户新建一个数据表。win32下建立新的MySQL空数据库很简单,只要在“/mysql/data/”目录下建立一个文件夹,如:"/usrinfo/",就可以了。而向库中增添新表可通过以下程序实现:
# connect.mysql--连接数据库 #
connection = mysql_connect();
mysql_select_db("usrinfo", connection);
?>;
# make.php-- 建立如下结构的,以用户名为表名的数据表 #
//调用connect.mysql
require("connect.mysql");
//检查以用户名为表名的数据表存在否? query="select count(*) from usrname";
result=mysql_db_query( query);
//不存在则创建,如存在就是老用户;
if(! result)
{ mysql_query("
create table usrname(
id tinyint(6),
title text,
body longtext,
dateof date;
timeof time; )") or die(mysql_error());
}
//此处为向数据表插入新的数据部分
?>

Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.

The main advantages of using database storage sessions include persistence, scalability, and security. 1. Persistence: Even if the server restarts, the session data can remain unchanged. 2. Scalability: Applicable to distributed systems, ensuring that session data is synchronized between multiple servers. 3. Security: The database provides encrypted storage to protect sensitive information.

Implementing custom session processing in PHP can be done by implementing the SessionHandlerInterface interface. The specific steps include: 1) Creating a class that implements SessionHandlerInterface, such as CustomSessionHandler; 2) Rewriting methods in the interface (such as open, close, read, write, destroy, gc) to define the life cycle and storage method of session data; 3) Register a custom session processor in a PHP script and start the session. This allows data to be stored in media such as MySQL and Redis to improve performance, security and scalability.

SessionID is a mechanism used in web applications to track user session status. 1. It is a randomly generated string used to maintain user's identity information during multiple interactions between the user and the server. 2. The server generates and sends it to the client through cookies or URL parameters to help identify and associate these requests in multiple requests of the user. 3. Generation usually uses random algorithms to ensure uniqueness and unpredictability. 4. In actual development, in-memory databases such as Redis can be used to store session data to improve performance and security.

Managing sessions in stateless environments such as APIs can be achieved by using JWT or cookies. 1. JWT is suitable for statelessness and scalability, but it is large in size when it comes to big data. 2.Cookies are more traditional and easy to implement, but they need to be configured with caution to ensure security.


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