laravel中Container依賴注入，多次生成類實例

看laravel中Comtroller發(fā)現(xiàn)，類依賴注入時，當(dāng)我通過make創(chuàng)建對象時，發(fā)現(xiàn)依賴被創(chuàng)建了多份實例。

代碼如下：

<?php

namespace Tests\Unit;

use Illuminate\Container\Container;
use Tests\TestCase;

interface SessionStorage
{
    public function get($key);

    public function set($key, $value);
}

class FileSessionStorage implements SessionStorage
{
    public function __construct()
    {
        echo "file init \n";
    }

    public function get($key)
    {
        // TODO: Implement get() method.
    }

    public function set($key, $value)
    {
        // TODO: Implement set() method.
    }
}

class MySqlSessionStorage implements SessionStorage
{
    public function __construct()
    {
        echo "mysql init \n";
    }

    public function get($key)
    {
        // TODO: Implement get() method.
    }

    public function set($key, $value)
    {
        // TODO: Implement set() method.

    }
}

class SimpleAuth
{
    protected $session;

    public function __construct(SessionStorage $session)
    {
        $this->session = $session;
    }

    public function get()
    {
        $this->session->get(null);
    }

}

class ExampleTest extends TestCase
{
    /**
     * A basic test example.
     *
     * @return void
     */
    public function testBasicTest()
    {
        $container = Container::getInstance();

        $container->bind( SessionStorage::class, MysqlSessionStorage::class );
        $container->make(SimpleAuth::class);
        echo "-\n";

        $container->bind( SessionStorage::class, FileSessionStorage::class );
        $container->make(SimpleAuth::class);
        echo "-\n";

        $container->bind( SessionStorage::class, MysqlSessionStorage::class );
        $container->make(SimpleAuth::class);
    }
}

代碼的輸出結(jié)果如下：

跟預(yù)期不同的地方：

1. 第一次make操作的時候，通過構(gòu)造函數(shù)的輸出，可以看出，依賴關(guān)系僅僅被實例化了一次
2. 但后面再次調(diào)用bind，make發(fā)現(xiàn)構(gòu)造函數(shù)被調(diào)用了兩次

mysql init 
-
file init 
file init 
-
mysql init 
mysql init 

嘗試debug：在make函數(shù)中記錄調(diào)用的次數(shù)。：

public function make($abstract, array $parameters = [])
{
    if (stripos($abstract, 'SessionStorage') !== false) {
        echo "make plus \n";
    }
    return $this->resolve($abstract, $parameters);
}

=================== 輸出結(jié)果 =================
make plus 
make plus 
mysql init 
-
make plus 
make plus 
file init 
make plus 
make plus 
file init 
-
make plus 
make plus 
mysql init 
make plus 
make plus 
mysql init 

怎么破！??！