将一个类注入另一个类

Question

我有一个类 InjectedClass 带有一个方法 someMethod。该类需要三个参数。我需要另一个类中方法的输出，Myclass。基本上，我需要通过 Myclass 中的构造函数将相同的三个参数传递给注入的类，因为它确实返回了一些数据。

问题是我收到一条错误消息，指出 Myclass 构造函数中的第四个参数（注入的类）应该是注入类的实例，但它是空的！请参阅示例。

我认为问题在于 Injected 类在没有参数的情况下被初始化，因此没有初始化，因此是空的。此外，如果我尝试将类直接注入 myfunction 方法，我会得到或多或少相同的结果。我该如何解决这个烂摊子？

class Myclass {

    private $var1;
    private $var2;
    private $var3;
    private $injectedclass;

    public function __construct($var1, $var2, $var3, InjectedClass $injectedclass)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
        $this->injectedclass = $injectedclass;
    }

    public function myfunction()
    {
        return $this->injectedclass($this->var1, $this->var2, $this->var3)->someMethod();
    }
}

class InjectedClass {

    private $var1;
    private $var2;
    private $var3;

    public function __construct($var1, $var2, $var3)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
    }

    public function someMethod()
    {
        // do stuff
    }
}

Answer 1

MyClass 在构造中只需要 1 个参数 - InjectedClass 实例，它可以工作了。即

$injected = new Injected($var1, $var2, $var);

$my = new MyClass($injected);

$my->myfunction(); // will work correctly now

Answer 2

我会重新考虑您是如何尝试使用依赖注入的。我想到的最简单的方法是在 InjectedClass 中创建设置器，并在您在构造中设置类变量时设置它们。比如：

class Myclass {

    private $var1;
    private $var2;
    private $var3;
    private $injectedclass;

    public function __construct($var1, $var2, $var3, InjectedClass $injectedclass)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
        $this->injectedclass = $injectedclass;
        $this->injectedclass->setParams($this->var1, $this->var2, $this->var3);
    }

    public function myfunction()
    {
        return $this->injectedclass($this->var1, $this->var2, $this->var3)->someMethod();
    }
}

class InjectedClass {

    private $var1;
    private $var2;
    private $var3;

    public function setParams($var1, $var2, $var3) {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
    }

    public function someMethod()
    {
        // do stuff
    }
}

当然，您可以稍微清理一下，但通过这种方式进行注入，您应该能够避免您面临的问题。

Answer 3

一切都取决于你想要达到的目标，但基本上在

public function myfunction()
{
   return $this->injectedclass($this->var1, $this->var2, $this->var3)->someMethod();
}

您不需要传递这些参数，因为$this->injectedclass 已经是已经初始化其属性的对象。所以代码应该是这样的：

class Myclass {

    private $var1;
    private $var2;
    private $var3;
    private $injectedclass;

    public function __construct($var1, $var2, $var3, InjectedClass $injectedclass)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
        $this->injectedclass = $injectedclass;
    }

    public function myfunction()
    {
        return $this->injectedclass->someMethod();
    }
}

class InjectedClass {

    private $var1;
    private $var2;
    private $var3;

    public function __construct($var1, $var2, $var3)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
    }

    public function someMethod()
    {
        // do stuff
        echo $this->var1.' '.$this->var2.' '.$this->var3."<br />";
    }
}

$m = new Myclass(1,2,3, new InjectedClass(1,2,3));
$m->myFunction();

但是，当您创建 Myclass 实例时，您需要将参数 1,2,3 传递给 Myclass 和 InjectedClass，如果这些值相同，这可能不太方便。

因此您可以将代码更改为：

class Myclass {

    private $var1;
    private $var2;
    private $var3;
    private $injectedclass;

    public function __construct($var1, $var2, $var3, InjectedClass $injectedclass)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
        $this->injectedclass = $injectedclass;
        $this->injectedclass->setParams($var1, $var2, $var3);
    }

    public function myfunction()
    {
        return $this->injectedclass->someMethod();
    }
}

class InjectedClass {

    private $var1;
    private $var2;
    private $var3;

    public function setParams($var1, $var2, $var3)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
    }

    public function someMethod()
    {
        // do stuff
        echo $this->var1.' '.$this->var2.' '.$this->var3."<br />";
    }
}

$m = new Myclass(1,2,3, new InjectedClass());
$m->myFunction();

因此您只将参数传递给Myclass，并将参数设置为InjectedClass。但是这种方法会导致即使您创建InjectedClass 类的对象，您也需要运行setParams 方法来设置参数，因此它不是最佳解决方案。

更好的是：

class Myclass {

    private $var1;
    private $var2;
    private $var3;
    private $injectedclass;

    public function __construct(InjectedClass $injectedclass)
    {
        $this->injectedclass = $injectedclass;
        list ($this->var1, $this->var2, $this->var3) = $this->injectedclass->getParams();
    }

    public function myfunction()
    {
        return $this->injectedclass->someMethod();
    }
}

class InjectedClass {

    private $var1;
    private $var2;
    private $var3;

    public function __construct($var1, $var2, $var3)
    {
        $this->var1 = $var1;
        $this->var2 = $var2;
        $this->var3 = $var3;
    }

    public function getParams() {
        return array ($this->var1, $this->var2, $this->var3);
    }

    public function someMethod()
    {
        // do stuff
        echo $this->var1.' '.$this->var2.' '.$this->var3."<br />";
    }
}

$m = new Myclass(new InjectedClass(1,2,3));
$m->myFunction();

InjectedClass 的对象可能会将这些参数返回给Myclass 的对象。