component依賴注射組件允許和集中化你程序?qū)ο髽?gòu)造方式

TheDependencyInjectionTheDependencyInjectioncomponentallowsyoutostandardizeandcentralizethewayobjectsareconstructedinyourapplication.ForanintroductiontoDependencyInjectionandservicecontainersseeService更多關(guān)于依賴注射和服務(wù)容器的介紹請看ServiceInstallationYoucaninstallthecomponentin2differentInstallitviaComposer(onUsetheofficialGitrepository 通過Composer安裝(on使用Git倉庫 BasicUsageYoumighthaveasimpleclasslikethe thatyouwanttomakeavailableasaYoucanregisterthisinthecontainerasaAnimprovementtotheclasstomakeitmoreflexiblewouldbetoallowthecontainertoset used.Ifyouchangetheclasssothisispassedintotheconstructor:ThenyoucansetthechoiceoftransportintheThisclassisnowmuchmoreflexibleasyouhaveseparatedthechoiceoftransportoutoftheimplementationandintothecontainer.Whichmailtransportyouhavechosenmaybesomethingotherservicesneedtoknowabout.Youcanavoidhavingtochangeitinmultiplecesbymakingitaparameterinthecontainerandthenreferringtothisparameterforthe service'sconstructorargument:你所選擇的郵件transport，或許其他服務(wù)也需要知道。你可以避免多次設(shè)置這個容器的參數(shù)，而通過這個Nowthatthe serviceisinthecontaineryoucaninjectitasadependencyofotherclasses.Ifyouhaveaclasslikethis:Thenyoucanregisterthisasaserviceaswellandpass serviceintoIfthedidnotrequirethe andinjectingitwasonlyoptionalthenyoucouldusesetterinjectioninstead:Youcannowchoosenottoinjecta intothe.Ifyoudowanttothoughthenthecontainercancallthesettermethod:YoucouldthengetyourservicefromthecontainerlikeAvoidingyour ingDependentontheContainerWhilstyoucanretrieveservicesfromthecontainerdirectlyitisbesttominimizethis.Forexample,theyouinjectedthe serviceinratherthanaskingforitfromthecontainer.Youcouldhaveinjectedthecontainerinandretrievedthe servicefromitbutitwouldthenbetiedtothisparticularcontainermakingitdifficulttoreusetheclasselsewhere.Youwillneedtogetaservicefromthecontaineratsomepointbutthisshouldbeasfewtimesaspossibleattheentrypointtoyourapplication.盡管你可以從容器直接取回服務(wù)，最好還是最小化它。例如，在NewsletterManager里你注射mailer通過從容器調(diào)用它強(qiáng)。你可以注射進(jìn)容器，并且從其中返回這個mae服務(wù)，但它被綁定到這個特定的容器里，使得很難在別處重復(fù)利用它。SettinguptheContainerwithConfigurationFilesAswellassettinguptheservicesusingPHPasaboveyoucanalsouseconfigurationfiles.ThisallowsyoutouseXMLorYAMLtowritethedefinitionsfortheservicesratherthanusingPHPtodefinetheservicesasintheaboveexamples.Inanythingbutthesmallestapplicationsitmakessensetoorganizetheservicedefinitionsbymovingthemintooneormoreconfigurationfiles.TodothisyoualsoneedtoinstalltheConfigLoadinganXMLconfig同上用PP建立服務(wù)一樣，你也可以使用配置文件。這里允許你使用XL或者AL來寫服務(wù)定義，而不是通過同上使用PP的方法定義服務(wù)。在任意很小的程序里，這給人一種感覺，通過移動它們到一個或更多配置文件里來管理服務(wù)定義。這樣做你需要安裝theonfgcompnet.LoadingaYAMLconfigIfyouwanttoloadYAMLconfigfilesthenyouwillalsoneedtoinstalltheYaml如果你想要加載YAML配置文件，你需要安裝theYa