Detailed analysis of thinkPHP5.0 framework automatic loading mechanism

This article mainly introduces the thinkPHP5.0 frameworkautomatic loadingmechanism, and analyzes the concept, principle, usage and related notes of thinkPHP5.0 automatic loading in more detail. Friends in need can refer to

The examples in this article describe the automatic loading mechanism of the thinkPHP5.0 framework. Share it with everyone for your reference, the details are as follows:

Overview

ThinkPHP5.0 truly realizes on-demand loading, and all class libraries use automatic Loading mechanism, and supports class library mapping and automatic loading of composer class libraries.

The implementation of automatic loading is completed by the think\Loader class library, and the automatic loading specification complies with PHP's PSR-4.

Automatic loading

Since the new version of ThinkPHP fully adopts the namespace feature, you only need to correctly define the namespace where the class library is located. If the path of the namespace is consistent with the directory of the class library file, then automatic loading of classes can be achieved.

The automatic loading detection sequence of class libraries is as follows:

1. Class library mapping detection;
2. PSR-4 automatic loading detection;
3. PSR-0 automatic loading Detection;

The system will detect in sequence. Once the detection takes effect, the corresponding class library file will be automatically loaded.

Class library mapping

If we follow our namespace definition specifications above, the automatic loading of the class library can basically be completed, but if more names are defined If there is less space, the efficiency will decrease, so we can define class library mappings for commonly used class libraries. Named class library mapping is equivalent to defining an alias for the class file, which is more efficient than namespace positioning, for example:

Loader::addClassMap('think\Log',LIB_PATH.'think\Log.php');
Loader::addClassMap('org\util\Array',LIB_PATH.'org\util\Array.php');

You can also use the addClassMap method to import class library mapping definitions in batches, for example:

$map = [
  'think\Log'   => LIB_PATH.'think\Log.php',
  'org\util\array'=> LIB_PATH.'org\util\Array.php'
];
Loader::addClassMap($map);

Although classes registered through class library mapping are not required to correspond to namespace directories, it is still recommended to follow the PSR-4 specification to define class libraries and directories.

Class library import

If you do not need the automatic loading function of the system, or do not use a namespace, you can also use the import method of the think\Loader class. Manually load class library files, for example:

Loader::import('org.util.array');
Loader::import('@.util.upload');

Example

// 引入 extends/qrcode.php
Loader::import('qrcode', EXTEND_PATH);
// 助手函数
import('qrcode', EXTEND_PATH);
// 引入 extends/wechat-sdk/wechat.class.php
Loader::import('wechat-sdk.wechat', EXTEND_PATH, '.class.php');
// 助手函数
import('wechat-sdk.wechat', EXTEND_PATH, '.class.php');

Class library import also uses a similar concept of namespace (but does not require actual namespace support), supported "root namespace" "include:

If you fully comply with the system's namespace definition, generally speaking, there is no need to manually load the class library file and just instantiate it directly.

Composer automatic loading

The 5.0 version supports automatic loading of class libraries installed by Composer. You can call them directly according to the namespace in the Composer dependent library.

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