


php functions, classes and objects, as well as class encapsulation, inheritance, class static methods, static properties, php static
<p>1、函数</p> <p>    php内置函数可以直接使用,如果没有安装php扩展即可</p> <p>    自定义函数</p> <pre class="code"><span>//</span><span>函数function 函数名 </span> <span>function</span> dump(<span>$var</span> = <span>null</span>){ <span>//</span><span>支出默认参数值</span> <span>echo</span> ‘<pre/><span>’; </span><span>var_dump</span>(<span>$var</span><span>); }</span>
2. Class and object (new Obj)
<?<span>php </span><span>//</span><span>定义一个人的类,现在还不是对象</span> <span>class</span><span> Person { </span><span>//</span><span>私有属性 </span>
<span> </span><span>private</span> <span>$eye</span> = '大眼睛'<span>; </span><span>private</span> <span>$mouth</span> = '小嘴巴'<span>; </span><span>private</span> <span>$leg</span> = '大长腿'<span>; </span><span>//</span><span>构造方法 new 对象的时候自定调用</span> <span>public</span> <span>function</span><span> __construct() { </span><span>echo</span> <span>__CLASS__</span><span>; } </span><span>public</span> <span>function</span><span> run() { </span><span>echo</span> <span>$this</span>-><span>leg; } </span><span>//</span><span>学习 会用到 腿(走路)、眼睛(看书)、嘴(念书)</span> <span>public</span> <span>function</span><span> study() { </span><span>echo</span> <span>$this</span>->leg, <span>$this</span>->eye, <span>$this</span>-><span>mouth; } } </span><span>//</span><span>使用类 new以后就变成了对象</span> <span>$person</span> = <span>new</span> Person(); <span>//</span><span>输出 Person</span> <span>$person</span> -> run(); <span>//</span><span>输出 大长腿</span> <span>$person</span> -> study(); <span>//</span><span>输出 大长腿 大眼睛 小嘴唇</span>
3. Class encapsulation (public, protected, private) and inheritance (extends)
<span>//</span><span>类的继承 </span> <span>class</span><span> A { </span><span>public</span> <span>function</span><span> help() { </span><span>echo</span> <span>__METHOD__</span><span>; } </span><span>//</span><span>声明一个吃的方法 私有的</span> <span>private</span> <span>function</span><span> eat() { </span><span>echo</span> <span>__METHOD__</span><span>; } } </span><span>//</span><span>子类可以继承父类所有的公共方法和属性、受保护的方法和属性,私有方法除外 //如果想使用,重写即可</span> <span>class</span> B <span>extends</span><span> A { </span><span>public</span> <span>function</span><span> doSomething() { </span><span>$this</span> -> help(); <span>//</span><span>继承了父类的方法 前提是声明为public </span> <span>echo</span> '<hr/>'<span>; </span><span>$this</span> -> eat(); <span>//</span><span>因为吃是私有的,子类不能使用, 这里在子类中写了一个eat方法.</span> <span> } </span><span>//</span><span>子类的吃</span> <span>public</span> <span>function</span><span> eat() { </span><span>echo</span> <span>__METHOD__</span><span>; } } </span><span>$b</span> = <span>new</span><span> B; </span><span>$b</span>->doSomething();
//输出结果
A::help
B::eat
4. Static methods and static properties of classes
<?<span>php </span><span>//</span><span>定义一个Url 相关的类</span> <span>class</span><span> Url { </span><span>public</span> <span>static</span> <span>function</span> createUrl(<span>$arr</span> =<span> []) { </span><span>echo</span> <span>__METHOD__</span><span>; } </span><span>public</span> <span>static</span> <span>function</span> redirect(<span>$url</span> = ''<span>) { </span><span>echo</span> <span>__METHOD__</span><span>; } </span><span>public</span> <span>static</span> <span>function</span><span> getCurrentUrl() { </span><span>echo</span> <span>__METHOD__</span><span>; } } </span><span>//</span><span>把方法声明成静态方法,不需要每次都实例化(new)对象,操作方便,节省内存,效率更高</span> <span>echo</span> Url::createUrl(<span>$var</span>=''<span>); </span><span>echo</span> Url::redirect(<span>$url</span>=''<span>); </span><span>echo</span> Url::getCurrentUrl();
5. Static attributes of classes
<?<span>php </span><span>//</span><span>定义一个Url 相关的类</span> <span>class</span><span> Url { </span><span>//</span><span>声明为类常量</span> <span>const</span> URL = 'http://www.baidu.com'; <span>//</span><span>从5.3以后可以直接在类外部使用 const //声明为静态变量</span> <span>public</span> <span>static</span> <span>$var</span> = 'it is very good'<span>; </span><span>public</span> <span>static</span> <span>function</span> createUrl(<span>$arr</span> =<span> []) { </span><span>echo</span> self::<span>URL; </span><span>echo</span> '<br/>'<span>; </span><span>echo</span> self::<span>$var</span><span>; </span><span>echo</span> '<br/>'<span>; </span><span>echo</span> <span>__METHOD__</span><span>; } </span><span>public</span> <span>static</span> <span>function</span> redirect(<span>$url</span> = ''<span>) { </span><span>echo</span> <span>__METHOD__</span><span>; } </span><span>public</span> <span>static</span> <span>function</span><span> getCurrentUrl() { </span><span>echo</span> <span>__METHOD__</span><span>; } } </span><span>//</span><span>把方法声明成静态方法,不需要每次都实例化(new)对象,操作方便,节省内存,效率更高</span> <span>echo</span> Url::createUrl(<span>$var</span>='');

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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