資訊專欄INFORMATION COLUMN
摘要：前言首先歡迎關注我的博客在前面幾個博客中，我詳細講了容器各個功能的使用綁定的源碼解析的源碼，今天這篇博客會詳細介紹容器的一些細節，一些特性，以便更好地掌握容器的功能。
前言
首先歡迎關注我的博客： www.leoyang90.cn
在前面幾個博客中，我詳細講了 Ioc 容器各個功能的使用、綁定的源碼、解析的源碼，今天這篇博客會詳細介紹 Ioc 容器的一些細節，一些特性，以便更好地掌握容器的功能。
注：本文使用的測試類與測試對象都取自 laravel 的單元測試文件src/illuminate/tests/Container/ContainerTest.php
rebind綁定特性 rebind 在綁定之前instance 和 普通 bind 綁定一樣，當重新綁定的時候都會調用 rebind 回調函數，但是有趣的是，對于普通 bind 綁定來說，rebind 回調函數被調用的條件是當前接口被解析過：
public function testReboundListeners()
{
unset($_SERVER["__test.rebind"]);
$container = new Container;
$container->rebinding("foo", function () {
$_SERVER["__test.rebind"] = true;
});
$container->bind("foo", function () {
});
$container->make("foo");
$container->bind("foo", function () {
});
$this->assertTrue($_SERVER["__test.rebind"]);
}
所以遇到下面這樣的情況,rebinding 的回調函數是不會調用的：
public function testReboundListeners()
{
unset($_SERVER["__test.rebind"]);
$container = new Container;
$container->rebinding("foo", function () {
$_SERVER["__test.rebind"] = true;
});
$container->bind("foo", function () {
});
$container->bind("foo", function () {
});
$this->assertFalse(isset($_SERVER["__test.rebind"]));
}
有趣的是對于 instance 綁定：
public function testReboundListeners()
{
unset($_SERVER["__test.rebind"]);
$container = new Container;
$container->rebinding("foo", function () {
$_SERVER["__test.rebind"] = true;
});
$container->bind("foo", function () {
});
$container->instance("foo", function () {
});
$this->assertTrue(isset($_SERVER["__test.rebind"]));
}
rebinding 回調函數卻是可以被調用的。其實原因就是 instance 源碼中 rebinding 回調函數調用的條件是 rebound 為真，而普通 bind 函數調用 rebinding 回調函數的條件是 resolved 為真. 目前筆者不是很清楚為什么要對 instance 和 bind 區別對待，希望有大牛指導。
rebind 在綁定之后為了使得 rebind 回調函數在下一次的綁定中被激活，在 rebind 函數的源碼中，如果判斷當前對象已經綁定過，那么將會立即解析：
public function rebinding($abstract, Closure $callback)
{
$this->reboundCallbacks[$abstract = $this->getAlias($abstract)][] = $callback;
if ($this->bound($abstract)) {
return $this->make($abstract);
}
}
單元測試代碼：
public function testReboundListeners1()
{
unset($_SERVER["__test.rebind"]);
$container = new Container;
$container->bind("foo", function () {
return "foo";
});
$container->resolving("foo", function () {
$_SERVER["__test.rebind"] = true;
});
$container->rebinding("foo", function ($container,$object) {//會立即解析
$container["foobar"] = $object."bar";
});
$this->assertTrue($_SERVER["__test.rebind"]);
$container->bind("foo", function () {
});
$this->assertEquals("bar", $container["foobar"]);
}
resolving 特性
resolving 回調的類型
resolving 不僅可以針對接口執行回調函數，還可以針對接口實現的類型進行回調函數。
public function testResolvingCallbacksAreCalledForType()
{
$container = new Container;
$container->resolving("StdClass", function ($object) {
return $object->name = "taylor";
});
$container->bind("foo", function () {
return new StdClass;
});
$instance = $container->make("foo");
$this->assertEquals("taylor", $instance->name);
}
public function testResolvingCallbacksShouldBeFiredWhenCalledWithAliases()
{
$container = new Container;
$container->alias("StdClass", "std");
$container->resolving("std", function ($object) {
return $object->name = "taylor";
});
$container->bind("foo", function () {
return new StdClass;
});
$instance = $container->make("foo");
$this->assertEquals("taylor", $instance->name);
}
resolving 回調與 instance
前面講過，對于 singleton 綁定來說，resolving 回調函數僅僅運行一次，只在 singleton 第一次解析的時候才會調用。如果我們利用 instance 直接綁定類的對象，不需要解析，那么 resolving 回調函數將不會被調用：
public function testResolvingCallbacksAreCalledForSpecificAbstracts()
{
$container = new Container;
$container->resolving("foo", function ($object) {
return $object->name = "taylor";
});
$obj = new StdClass;
$container->instance("foo", $obj);
$instance = $container->make("foo");
$this->assertFalse(isset($instance->name));
}
extend 擴展特性
extend 用于擴展綁定對象的功能，對于普通綁定來說，這個函數的位置很靈活：
在綁定前擴展public function testExtendIsLazyInitialized()
{
ContainerLazyExtendStub::$initialized = false;
$container = new Container;
$container->extend("IlluminateTestsContainerContainerLazyExtendStub", function ($obj, $container) {
$obj->init();
return $obj;
});
$container->bind("IlluminateTestsContainerContainerLazyExtendStub");
$this->assertFalse(ContainerLazyExtendStub::$initialized);
$container->make("IlluminateTestsContainerContainerLazyExtendStub");
$this->assertTrue(ContainerLazyExtendStub::$initialized);
}
在綁定后解析前擴展
public function testExtendIsLazyInitialized()
{
ContainerLazyExtendStub::$initialized = false;
$container = new Container;
$container->bind("IlluminateTestsContainerContainerLazyExtendStub");
$container->extend("IlluminateTestsContainerContainerLazyExtendStub", function ($obj, $container) {
$obj->init();
return $obj;
});
$this->assertFalse(ContainerLazyExtendStub::$initialized);
$container->make("IlluminateTestsContainerContainerLazyExtendStub");
$this->assertTrue(ContainerLazyExtendStub::$initialized);
}
在解析后擴展
public function testExtendIsLazyInitialized()
{
ContainerLazyExtendStub::$initialized = false;
$container = new Container;
$container->bind("IlluminateTestsContainerContainerLazyExtendStub");
$container->make("IlluminateTestsContainerContainerLazyExtendStub");
$this->assertFalse(ContainerLazyExtendStub::$initialized);
$container->extend("IlluminateTestsContainerContainerLazyExtendStub", function ($obj, $container) {
$obj->init();
return $obj;
});
$this->assertFalse(ContainerLazyExtendStub::$initialized);
$container->make("IlluminateTestsContainerContainerLazyExtendStub");
$this->assertTrue(ContainerLazyExtendStub::$initialized);
}
可以看出，無論在哪個位置，extend 擴展都有 lazy 初始化的特點，也就是使用 extend 函數并不會立即起作用，而是要等到 make 解析才會激活。
extend 與 instance 綁定對于 instance 綁定來說，暫時 extend 的位置需要位于 instance 之后才會起作用，并且會立即起作用，沒有 lazy 的特點：
public function testExtendInstancesArePreserved()
{
$container = new Container;
$obj = new StdClass;
$obj->foo = "foo";
$container->instance("foo", $obj);
$container->extend("foo", function ($obj, $container) {
$obj->bar = "baz";
return $obj;
});
$this->assertEquals("foo", $container->make("foo")->foo);
$this->assertEquals("baz", $container->make("foo")->bar);
}
extend 綁定與 rebind 回調
無論擴展對象是 instance 綁定還是 bind 綁定，extend 都會啟動 rebind 回調函數：
public function testExtendReBindingInstance()
{
$_SERVER["_test_rebind"] = false;
$container = new Container;
$container->rebinding("foo",function (){
$_SERVER["_test_rebind"] = true;
});
$obj = new StdClass;
$container->instance("foo",$obj);
$container->make("foo");
$container->extend("foo", function ($obj, $container) {
return $obj;
});
this->assertTrue($_SERVER["_test_rebind"]);
}
public function testExtendReBinding()
{
$_SERVER["_test_rebind"] = false;
$container = new Container;
$container->rebinding("foo",function (){
$_SERVER["_test_rebind"] = true;
});
$container->bind("foo",function (){
$obj = new StdClass;
return $obj;
});
$container->make("foo");
$container->extend("foo", function ($obj, $container) {
return $obj;
});
this->assertFalse($_SERVER["_test_rebind"]);
}
contextual 綁定特性
contextual 在綁定前
contextual 綁定不僅可以與 bind 綁定合作，相互不干擾，還可以與 instance 綁定相互合作。而且 instance 的位置也很靈活，可以在 contextual 綁定前，也可以在contextual 綁定后：
public function testContextualBindingWorksForExistingInstancedBindings()
{
$container = new Container;
$container->instance("IlluminateTestsContainerIContainerContractStub", new ContainerImplementationStub);
$container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");
$this->assertInstanceOf(
"IlluminateTestsContainerContainerImplementationStubTwo",
$container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
);
}
contextual 在綁定后
public function testContextualBindingWorksForNewlyInstancedBindings()
{
$container = new Container;
$container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");
$container->instance("IlluminateTestsContainerIContainerContractStub", new ContainerImplementationStub);
$this->assertInstanceOf(
"IlluminateTestsContainerContainerImplementationStubTwo",
$container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
);
}
contextual 綁定與別名
contextual 綁定也可以在別名上進行，無論賦予別名的位置是 contextual 的前面還是后面：
public function testContextualBindingDoesntOverrideNonContextualResolution()
{
$container = new Container;
$container->instance("stub", new ContainerImplementationStub);
$container->alias("stub", "IlluminateTestsContainerIContainerContractStub");
$container->when("IlluminateTestsContainerContainerTestContextInjectTwo")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");
$this->assertInstanceOf(
"IlluminateTestsContainerContainerImplementationStubTwo",
$container->make("IlluminateTestsContainerContainerTestContextInjectTwo")->impl
);
$this->assertInstanceOf(
"IlluminateTestsContainerContainerImplementationStub",
$container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
);
}
public function testContextualBindingWorksOnNewAliasedBindings()
{
$container = new Container;
$container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");
$container->bind("stub", ContainerImplementationStub::class);
$container->alias("stub", "IlluminateTestsContainerIContainerContractStub");
$this->assertInstanceOf(
"IlluminateTestsContainerContainerImplementationStubTwo",
$container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
);
}
爭議
目前比較有爭議的是下面的情況：
public function testContextualBindingWorksOnExistingAliasedInstances()
{
$container = new Container;
$container->alias("IlluminateTestsContainerIContainerContractStub", "stub");
$container->instance("stub", new ContainerImplementationStub);
$container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("stub")->give("IlluminateTestsContainerContainerImplementationStubTwo");
$this->assertInstanceOf(
"IlluminateTestsContainerContainerImplementationStubTwo",
$container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
);
}
由于instance的特性，當別名被綁定到其他對象上時，別名 stub 已經失去了與 IlluminateTestsContainerIContainerContractStub 之間的關系，因此不能使用 stub 代替作上下文綁定。
但是另一方面：
public function testContextualBindingWorksOnBoundAlias()
{
$container = new Container;
$container->alias("IlluminateTestsContainerIContainerContractStub", "stub");
$container->bind("stub", ContainerImplementationStub::class);
$container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("stub")->give("IlluminateTestsContainerContainerImplementationStubTwo");
$this->assertInstanceOf(
"IlluminateTestsContainerContainerImplementationStubTwo",
$container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
);
}
代碼只是從 instance 綁定改為 bind 綁定，由于 bind 綁定只切斷了別名中的 alias 數組的聯系，并沒有斷絕abstractAlias數組的聯系，因此這段代碼卻可以通過，很讓人難以理解。本人在給 Taylor Otwell 提出 PR 時，作者原話為“I"m not making any of these changes to the container on a patch release.”。也許，在以后(5.5或以后)版本作者會更新這里的邏輯，我們就可以看看服務容器對別名綁定的態度了，大家也最好不要這樣用。
服務容器中的閉包函數參數服務容器中很多函數都有閉包函數，這些閉包函數可以放入特定的參數，在綁定或者解析過程中，這些參數會被服務容器自動帶入各種類對象或者服務容器實例。
bind 閉包參數public function testAliasesWithArrayOfParameters()
{
$container = new Container;
$container->bind("foo", function ($app, $config) {
return $config;
});
$container->alias("foo", "baz");
$this->assertEquals([1, 2, 3], $container->makeWith("baz", [1, 2, 3]));
}
extend 閉包參數
public function testExtendedBindings()
{
$container = new Container;
$container["foo"] = "foo’;
$container->extend("foo", function ($old, $container) {
return $old."bar’;
});
$this->assertEquals("foobar", $container->make("foo"));
$container = new Container;
$container->singleton("foo", function () {
return (object) ["name" => "taylor"];
});
$container->extend("foo", function ($old, $container) {
$old->age = 26;
return $old;
});
$result = $container->make("foo");
$this->assertEquals("taylor", $result->name);
$this->assertEquals(26, $result->age);
$this->assertSame($result, $container->make("foo"));
}
bindmethod 閉包參數
public function testCallWithBoundMethod()
{
$container = new Container;
$container->bindMethod("IlluminateTestsContainerContainerTestCallStub@unresolvable", function ($stub,$container) {
$container["foo"] = "foo";
return $stub->unresolvable("foo", "bar");
});
$result = $container->call("IlluminateTestsContainerContainerTestCallStub@unresolvable");
$this->assertEquals(["foo", "bar"], $result);
$this->assertEquals("foo",$container["foo"]);
}
resolve 閉包參數
public function testResolvingCallbacksAreCalledForSpecificAbstracts()
{
$container = new Container;
$container->resolving("foo", function ($object，$container) {
return $object->name = "taylor";
});
$container->bind("foo", function () {
return new StdClass;
});
$instance = $container->make("foo");
$this->assertEquals("taylor", $instance->name);
}
rebinding 閉包參數
public function testReboundListeners()
{
$container = new Container;
$container->bind("foo", function () {
return "foo";
});
$container->rebinding("foo", function ($container,$object) {
$container["bar"] = $object."bar";
});
$container->bind("foo", function () {
});
$this->assertEquals("bar",$container["foobar"]);
}
文章版權歸作者所有，未經允許請勿轉載,若此文章存在違規行為，您可以聯系管理員刪除。
轉載請注明本文地址：http://specialneedsforspecialkids.com/yun/23012.html
摘要：劃下重點，服務容器是用于管理類的依賴和執行依賴注入的工具。類的實例化及其依賴的注入，完全由服務容器自動的去完成。 本文首發于 深入剖析 Laravel 服務容器，轉載請注明出處。喜歡的朋友不要吝嗇你們的贊同，謝謝。 之前在 深度挖掘 Laravel 生命周期 一文中，我們有去探究 Laravel 究竟是如何接收 HTTP 請求，又是如何生成響應并最終呈現給用戶的工作原理。 本章將帶領大...
摘要：哲學的一個重要組成部分就是容器，也可以稱為服務容器。那我們要怎么做呢請看下面的例子數據庫連接通過上面的代碼，如果我們想把改成，根本不需要去修改類構造函數里的依賴。現在我要講下容器里到底發生了什么。 showImg(https://segmentfault.com/img/remote/1460000018868909); IOC 容器是一個實現依賴注入的便利機制 - Taylor?Ot...
摘要：前言年底了不太忙，最近一段時間也一直在研究，就想寫篇關于比較深一點的教程系列啥的，于是就找到站長給開了寫教程的渠道。優點的就是為藝術家創造的框架，它也是工程化的趨勢。項目維護方便也是事實。如果有遇到問題可以直接在教程下面留言。 前言 年底了不太忙，最近一段時間也一直在研究laravel，就想寫篇關于laravel比較深一點的教程系列啥的，于是就找到站長給開了寫教程的渠道。由于第一次寫，...
摘要：如何實現持久化持久化，將在內存中的的狀態保存到硬盤中，相當于備份數據庫狀態。相當于備份數據庫接收到的命令，所有被寫入的命令都是以的協議格式來保存的。 最近社區里面有一篇文章引起了最多程序猿的關注，Laravel、PHPer 面試可能會遇到的問題，看評論區不少小伙伴們被難倒，對于一些問題同樣難倒了我（其實有很多啦），趁著周末有空，又總結梳理了一遍，順便來答一波題。由于個人技術水平有限，答...
閱讀 1293·2021-11-16 11:44
閱讀 3759·2021-10-09 10:01
閱讀 1745·2021-09-24 10:31
閱讀 3833·2021-09-04 16:41
閱讀 2510·2021-08-09 13:45
閱讀 1210·2019-08-30 14:08
閱讀 1776·2019-08-29 18:32
閱讀 1640·2019-08-26 12:12
