[toc]

1. 定义一个契约(接口)

app\Contracts\SuperModuleContract.php

<?php
namespace App\Contracts;

interface SuperModuleContract
{
    //激活超能力,这里参数必须是array，这就是一个规范
    public function activate(array $target);
}

2. 一个实现这个接口的类

app\Services\FlyPower.php

<?php
namespace App\Services;

use App\Contracts\SuperModuleContract;

class FlyPower implements SuperModuleContract
{
   public function activate(array $target)
   {
        //..可以根据$target 参数进行一些操作
         
        $ability = 'fly ability';
        return $ability; 
    }
}

3. 创建服务提供者

app\Providers\SuperPowerProvider.php

<?php
namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use App\Services\FlyPower;

class SuperPowerProvider extends ServiceProvider
{
    public function boot()
    {
        //
    }
    public function register()
    {
        //singleton绑定单例
        //如何使用:App::make('fly_power')方法时调用
        $this->app->singleton('fly_power',function(){
            return new FlyPower();
        });

        //bind绑定实例到接口以便依赖注入
        // 如何使用:在类构造方法中实例化，并指定接口类型
        $this->app->bind('App\Contracts\SuperModuleContract',function(){
            return new FlyPower();
        });
    }
}

4. 注册服务提供者

配置文件config/app.php的providers数组中：

'providers' => [
    //其他服务提供者
    App\Providers\SuperPowerProvider::class,
],

5. 创建facades

app\Facades\FlyPower.php

<?php
namespace App\Facades;
use Illuminate\Support\Facades\Facade;
class  FlyPower extends Facade
{
    protected static function getFacadeAccessor()
    {
        return 'fly_power';
    }
}

6. 再然后需要到配置文件config/app.php中注册门面类别名：

'aliases' => [
    ...//其他门面类别名映射
    'FlyPower' => App\Facades\FlyPower::class,
],

7. 写一个控制器进行测试

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Contracts\SuperModuleContract;
use App;
use FlyPower;

class TestController extends Controller
{

    protected $superower;

    public function __construct(SuperModuleContract $super_power)
    {   
        $this->super_power = $super_power;
    }

    public function getPower(Request $request){
        //实现超人的几种方式
        
        # 使用make方式
        $superman1 = App::make('fly_power')->activate(array());
        
        # 使用facades
        $superman2 = FlyPower::activate(array());
        
        # 构造函数，类型提示，依赖注入
        $superman3 = $this->super_power->activate(array());
        
        dd($superman1, $superman2, $superman3);
    }

}

结果：

"fly ability"
"fly ability"
"fly ability"

证明三个超人类都实现了。

8. 进一步分析

当有超人有多种超能力的时候怎么办

8.1 定义一个获取超能力的接口

app\Contracts\GetPowerContract.php

<?php
namespace App\Contracts;

interface GetPowerContract
{
    public function init();
}

8.2 一个实现获取超能力接口的类

app\Services\GetPower.php

<?php
namespace App\Services;

use App\Contracts\GetPowerContract;
use App;

class GetPower implements GetPowerContract
{
    public function init()
    {   
        $config = config('power');
        $ability = $config['ability'];
        
        $ability = App::make($ability);
        return $ability;
    }
}

8.3 创建配置文件

app\config\power.php

<?php

return [
    'ability' => 'fly_power',
];

8.4 增加一个超能力类，需要实现超能力接口

app\Services\ShotPower.php

<?php
namespace App\Services;

use App\Contracts\SuperModuleContract;

class ShotPower implements SuperModuleContract
{
   public function activate(array $target)
   {
        //..可以根据$target 参数进行一些操作
         
        $ability = 'shot ability';
        return $ability; 
    }
}

8.5 修改服务提供器

app\Providers\SuperPowerProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use App\Services\FlyPower;
use App\Services\ShotPower;
use App\Services\GetPower;

class SuperPowerProvider extends ServiceProvider
{
    /** 
     * Bootstrap the application services.
     *
     * @return void
     */
    public function boot()
    {   
        //  
    }

    /** 
     * Register the application services.
     *
     * @return void
     */
    public function register()
    {   
        //singleton绑定单例
        //如何使用:App::make('fly_power')方法时调用
        $this->app->singleton('fly_power',function(){
            return new FlyPower();
        }); 

        $this->app->singleton('shot_power',function(){
            return new ShotPower();
        }); 

        //bind绑定实例到接口以便依赖注入
        // 如何使用:在类构造方法中实例化，并指定接口类型
        $this->app->bind('App\Contracts\SuperModuleContract',function(){
            return new FlyPower();
        }); 

        $this->app->bind('App\Contracts\GetPowerContract',function(){
            //return new FlightPower();
            return new GetPower();
        }); 
    }
}

8.6 修改控制器测试代码

app\Services\ShotPower.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
//use App\Services\XPower;
use App\Contracts\SuperModuleContract;
use App\Contracts\GetPowerContract;
use App;
use FlyPower;

class TestController extends Controller
{

    protected $superower;

    //public function __construct(XPower $XPower)
    //{ 
    //    $this->XPower = $XPower;
    //} 

    //public function __construct(SuperModuleContract $super_power)
    //{ 
    //    $this->super_power = $super_power;
    //} 

    public function __construct(GetPowerContract $super_power)
    {   
        $this->super_power = $super_power;
    }

    public function getPower(Request $request){
        //实现超人的几种方式
        $superman1 = App::make('fly_power')->activate(array());
        $superman2 = FlyPower::activate(array());
        $superman3 = $this->super_power->init()->activate(array());
        $superman4 = App::make('shot_power')->activate(array());
        

        d($superman1, $superman2, $superman3, $superman4);
    }


}

结果

"fly ability"
"fly ability"
"fly ability"
"shot ability"

说明我们赋予的shot超能力可以正常激活

修改config/power.php内容

<?php

return [
    'ability' => 'shot_power',
];

结果

"fly ability"
"fly ability"
"shot ability"
"shot ability"

第三行的更改，说明我们可以通过更改config的方式实现快速切换超人拥有的超能力