Detailed explanation of thinkPHP5.0 framework namespace

This article mainly introduces the thinkPHP5.0 framework namespace, and combines specific examples with a detailed analysis of the concepts, functions and related usage methods of namespaces in thinkPHP5.0. Friends who need it can refer to it

This article describes the thinkPHP5.0 framework namespace with examples. Share it with everyone for your reference, the details are as follows:

Namespace

ThinkPHP uses the namespace method to define and automatically load class library files, which effectively solves the problem of multi-module and Namespace conflicts between Composer class libraries, and a more efficient automatic loading mechanism for class libraries has been implemented.

If you don’t know the basic concept of namespace, you can refer to the PHP manual: PHP namespace

Special attention is, If you need to call PHP’s built-in class library, or a third party For class libraries that do not use namespaces, remember to add \ when instantiating the class library, for example:

// 错误的用法
$class = new stdClass();
$xml = new SimpleXmlElement($xmlstr);
// 正确的用法
$class = new \stdClass();
$xml = new \SimpleXmlElement($xmlstr);

In ThinkPHP5.0, You only need to correctly define the namespace where the class library is located, and the path of the namespace is consistent with the directory of the class library file, then automatic loading of the class can be achieved, thereby achieving true lazy loading.

For example, the \think\cache\driver\File class is defined as:

namespace think\cache\driver;
class File
{
}

If we instantiate this class, it should be ：

$class = new \think\cache\driver\File();

The system will automatically load the class file corresponding to the path of this class. The path where it is located is thinkphp/library/think/cache/driver/File.php .

5.0 The default directory specification is lowercase, class file naming is camel case, and the first letter is capitalized.

In principle, directories named in camel case can be supported, as long as the namespace definition is consistent with the directory, for example:

We instantiate

$class = new \Think\Cache\Driver\File();

The system will automatically load the thinkphp/library/Think/Cache/Driver/File.php file.

Root namespace (class library package)

The root namespace is a key concept, taking the above \think\cache\driver\File class as an example, think is a root namespace, and its corresponding initial namespace directory is the system's class library directory (thinkphp/library/think). We can simply understand that a root namespace corresponds to a class library package.

Several root namespaces (class library packages) built into the system are as follows:

Name	Description	Class library directory
think	System core class library	thinkphp/library/think
traits	System Trait class library	thinkphp/ library/traits
app	Application library	application

如果需要增加新的根命名空间，有两种方式：注册新的根命名空间或者放入EXTEND_PATH目录（自动注册）。

请注意本文中的示例代码为了简洁，如无指定类库的命名空间的话，都表示指的是think命名空间，例如下面的代码：

Route::get('hello','index/hello');

请自行使用：

use think\Route

或者：

\think\Route::get('hello','index/hello');

自动注册

我们只需要把自己的类库包目录放入EXTEND_PATH目录（extend，可配置），就可以自动注册对应的命名空间，例如：

我们在extend目录下面新增一个my目录，然后定义一个\my\Test类（ 类文件位于extend/my/Test.php）如下：

namespace my;
class Test
{
 public function sayHello()
 {
  echo 'hello';
 }
}

我们就可以直接实例化和调用：

$Test = new \my\Test();
$Test->sayHello();

如果我们在应用入口文件中重新定义了EXTEND_PATH常量的话，还可以改变\my\Test类文件的位置，例如：

define('EXTEND_PATH','../vendor/');

那么\my\Test类文件的位置就变成了/vendor/my/File.php。

手动注册

也可以通过手动注册的方式注册新的根命名空间，例如：

在应用入口文件中添加下面的代码：

\think\Loader::addNamespace('my','../application/extend/my/');

如果要同时注册多个根命名空间，可以使用：

\think\Loader::addNamespace([
 'my' => '../application/extend/my/',
 'org' => '../application/extend/org/',
]);

也可以直接在应用的配置文件中添加配置，系统会在应用执行的时候自动注册。

'root_namespace' => [
 'my' => '../application/extend/my/',
 'org' => '../application/extend/org/',
]

应用类库包

为了避免和Composer自动加载的类库存在冲突 ，应用类库的命名空间的根都统一以app命名，例如：

namespace app\index\model;
class User extends \think\Model
{
}

其类文件位于 application/index/model/User.php。

namespace app\admin\Event;
class User
{
}

其类文件位于 application/admin/event/User.php。

如果觉得app根命名空间不合适或者有冲突，可以在应用配置文件中修改：

'app_namespace' => 'application',

定义后，应用类库的命名空间改为：

namespace application\index\model;
class User extends \think\Model
{
}

命名空间别名

框架允许给命名空间定义别名，例如：

namespace app\index\model;
use think\Model;
class User extends Model
{
}

原来在控制器里面调用方式为：

namespace app\index\controller;
use app\index\model\User;
class Index
{
 public function index()
 {
  $user = new User();
 }
}

如果我们在应用公共文件中注册命名空间别名如下：

\think\Loader::addNamespaceAlias('model','app\index\model');

那么，上面的控制器代码就可以更改为：

namespace app\index\controller;
use model\User;
class Index
{
 public function index()
 {
  $user = new User();
 }
}

本文后续的章节，均建立在你已经了解PHP命名空间的基础之上，如果不掌握请自行补充PHP基础，否则你在后续的文档和ThinkPHP5.0的学习过程中，对命名空间的缺乏理解会成为你最大的学习障碍。

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