Laravel中使用Ioc容器的singleton方法和bind方法创建实例的区别

它们两个都是返回一个类的实例，不同的是singleton是单例模式，而bind是每次返回一个新的实例，看下面的两个例子。

1.Ioc容器bind方法

<?php
require __DIR__.'/../bootstrap/autoload.php';


class tanteng

{

    public $name;

}



$container = new Illuminate\Container\Container();

$container->bind('tanteng');

$instance = $container->make('tanteng');

$instance->name = 'tanteng';

$instance2 = $container->make('tanteng');

$instance2->name = 'tuntun';


echo $instance->name.' '.$instance2->name;

输出的结果：

tanteng tuntun

结论：

通过bind方法创建实例不是单例模式，而是创建新的实例。

2.Ioc容器singleton方法

<?php
require __DIR__.'/../bootstrap/autoload.php';


class single

{

    public $value;

}


$container = new Illuminate\Container\Container();


$container->singleton('single');

$instance3 = $container->make('single');

$instance4 = $container->make('single');



$instance3->value = 'aaaa';

$instance4->value = 'bbbb';



echo $instance3->value.' '.$instance4->value;

输出结果：

bbbb bbbb

结论：

使用singleton创建实例使用的是单例模式，每次返回同一个实例。

以上代码可以放在public下，如test.php运行。

再看框架底层代码：

public function singleton($abstract, $concrete = null)
{
    $this->bind($abstract, $concrete, true);
}

发现singleton方法其实也是调用bind方法，只是最后一个参数是true，表示单例模式。框架源代码：Illuminate/Container/Container.php

附上bind()方法

public function bind($abstract, $concrete = null, $shared = false)
    {
        $abstract = $this->normalize($abstract);

        $concrete = $this->normalize($concrete);

        // If the given types are actually an array, we will assume an alias is being
        // defined and will grab this "real" abstract class name and register this
        // alias with the container so that it can be used as a shortcut for it.
        if (is_array($abstract)) {
            list($abstract, $alias) = $this->extractAlias($abstract);

            $this->alias($abstract, $alias);
        }

        // If no concrete type was given, we will simply set the concrete type to the
        // abstract type. After that, the concrete type to be registered as shared
        // without being forced to state their classes in both of the parameters.
        $this->dropStaleInstances($abstract);

        if (is_null($concrete)) {
            $concrete = $abstract;
        }

        // If the factory is not a Closure, it means it is just a class name which is
        // bound into this container to the abstract type and we will just wrap it
        // up inside its own Closure to give us more convenience when extending.
        if (! $concrete instanceof Closure) {
            $concrete = $this->getClosure($abstract, $concrete);
        }

        $this->bindings[$abstract] = compact('concrete', 'shared');

        // If the abstract type was already resolved in this container we'll fire the
        // rebound listener so that any objects which have already gotten resolved
        // can have their copy of the object updated via the listener callbacks.
        if ($this->resolved($abstract)) {
            $this->rebound($abstract);
        }
    }