STRUTS2零配置

1、簡述STRUTS2Convention零酉己置從 struts2.1 開始，struts2 不再推薦使用 Codebehind 作為零配置插件，而是改為使用 Convention 插件來支持零配置，和 Codebehind 相比，Convention 插件更徹底，該插件完全拋棄配置信息，不僅不需要是使用 struts.xml 文件進行配置，甚至不需要使用 Annotation 進行配置，而是由 struts2 根據(jù)約定自動配置。如何使用 Convention1.將 struts-Convention-plugin-2.1.6.jar 文件復制到 WEB-INF/lib 路徑下2.對于 Conv

2、ention 插件而言，它會自動搜索位于 action,actions,struts,struts2 包下的所有 java 類，Convention 插件會把如下兩種 java 類當成 Action 處理：1)所有實現(xiàn)了 com.opensymphony.xwork2.Action 的 java 類2)所有類名以 Action 結尾的 java 類3.Convention 插件還允許設置如下三個常量：1)struts.Convention.exclude.packges:指定不掃描哪些包下的 java 類，位于這些包結構下的java 類將不會自動映射成 Action；2)struts.conv

3、ention.package.locators:Convention 插件使用該常量指定的包作為搜尋 Action的根包。對于 actions.fore.LoginAction 類，按約定原本應映射到/fore/login;如果將該常量設為 fore,則該 Action 將會映射到/login3)struts.convention.action.packages:Convention 插件以該常量指定包作為根包來搜索 Action類。Convention 插件除了掃描 action,actions,struts,struts2 四個包的類以外，還會掃描該常量指定的一個或多個包，Conventi

4、on 會視圖從中發(fā)現(xiàn) Action 類。注意：struts.convention.package.locators 和 struts.convention.action.packages 兩個常量的作用比較微妙，開發(fā)者在利用這兩個常量時務必小心。如：下面 Action 所在包被映射的命名空間如下：com.fun.actions.LoginAction 映射至 U/com.fun.actions.myoffice.CarInfoAction 映射至 U/myofficecom.fun.struts.myoffice.EntINfoAction 映射至 U/myofiice4.映射 Action

5、的 name 時，遵循如下兩步規(guī)則：1)如果該 Action 類名包含 Action 后綴，將該 Action 類名的 Action 后綴去掉。否則不做任何處理。2)將 Action 類名的駝峰寫法(每個單詞首字母大寫、其他字母小寫的寫法)轉成中畫線寫法(所有字母小寫，單詞與單詞之間以中畫線隔開)如 ： LoginAction 映 射 的 Acion 的 name 屬 性 為 login,GetBooks 映 射 的 Action 的 name 的 屬 性 為get-books,AddEmployeeAction 映射的 Action 的 name 屬性為 add-employee5.默認情況

6、下。Convention 總會到 WE 無用的 WEB-INF/content 路徑下定位物理資源，定位資源的約定是：actionRUL+resultCODE+suffix。當某個邏輯視圖找不到對應的視圖資源時，Convention會自動視圖使用 ActionURL+suffix 作為物理視圖資源。如：actions.fore.LoginAction 返回 success 字符串時，Convention 優(yōu)先考慮使用 WEB-INF/content/fore 目錄下的 login-success.jsp 作為視圖資源。如果找不到該文件，login.jsp 也可作為對應的視圖資源。如果返回 in

7、put 字符串，Convention 會將 WEB-INF/content/fore 里面查找login-input.jsp6.為了看到 struts2 應用里的 Action 等各種資源的影射情況，struts2 提供了 ConfigBrowser 插件。使用方法，將 struts2-config-browser-plugin-2.1.6.jar 文件復制到 struts2 應用的 WEB-INFlib目錄中。打開首頁地址：http:/localhost:8080/應用名字/config-browser/actionNames.action 這里可以看到 ConfigBrowser 插件的首

8、頁。注意：這里不管開發(fā)者是否使用 struts.xml 文件進行配置，一樣可以看到 struts 的配置信息。7.Action 鏈的約定如果希望一個 Action 處理結束后不是進入一個視圖頁面，而是進行另一個 Action 形成的 Action 鏈,通過 Convention 插件則只需遵守如下三個約定即可。1)第一個 Action 返回的邏輯視圖字符串沒有對應的視圖資源2)第二個 Action 與第一個 Action 處在同一個包下3)第二個 Action 影射的 URL 為：firstActionURL+resultCODE如，第一個 Action 為 OneAction,里面有個方法返

9、回為two,那么就得保證，WEB-INF/content/下沒有 one.jsp 或 one-two.jsp 對于第二個 action 它的名字應該是 OneTwoAction,而對應的 url應該是：“one-two.action”注意：由于 Convention 插件根據(jù) Action 和 jsp 頁面來動態(tài)生成映射的，因此不管是 Acion 的改變,還是 JSP 頁面的改變都需要 Convention 插件重新加載映射。那么只要我們?yōu)?struts2 應用配置如下兩個常量就可以了。屬性值3)Action 中還可以指定一個 params 屬性， 該屬性是一個字符串數(shù)組， 用于該 Acion

10、 指定的參數(shù)名和參數(shù)值。params 屬性應遵守如下格式：namel,valuel,name2,value24)Actions 也用于修飾 Action 類里的方法，用于將該方法映射到多個 URL.Actions 用于組織多個Action,因此它可將一個方法映射成多個邏輯 Action。如:packagecom.fun.actions;importorg.apache.struts2.convention.annotation.Action;importorg.apache.struts2.convention.annotation.Actions;importcom.fun.service.

11、LoginService;importcom.opensymphony.xwork2.ActionSupport;”value=”true”/是否從包中搜索 Action插件以該常量指定包作為根包publicclassLoginActionextendsActionSupportprivateStringstr;Actions(Action(value=login1,params=str,這是已經(jīng)注入的了！),Action(value=login2)publicStringlogin()returnstr;Action(value=ggg)publicStringabc()returnabc;

12、publicStringgetStr()returnstr;publicvoidsetStr(Stringstr)this.str=str;我們可以通過/login1.action 訪問，而在訪問時，str 這個屬性已經(jīng)有值，為 str=這是已經(jīng)注入的！”返回的視圖是 login1-str.jsp當我們用/login2.action 訪問時， str 的值為 null。 返回的視圖為 login2-str.jsp 而我們通過/ggg.action 調用的是 abc()方法，返回的視圖為/ggg-abc.jsp8.與 Result 配置相關的 Annotation1) ResultPathRes

13、ult 和 Results2) Results用于組織多個Result因此它只需指定一個value屬性值， 該value屬性值為多個Result3)Result相當于 struts.xml 文件中的result/元素的做喲歐諾個。使用Result 必須指定一個 name 屬性，相當于resultname=/另外，它還有幾個可選的屬性。type 相當于resulttype=/指定返回視圖資源的類型location 相當于result,./result中間部分，用于指定實際視圖位置params：該屬性相當于result/元素里多個param./子元素的作用， 用于為該 Result 指定參數(shù)值。該

14、屬性應滿足name1,value1,name2,value2格式 4)Result 有以下兩種用法1Action 級的 Result 映射：以Actions 組合多個Action 后修飾的 Action 類。這種 Result 映射對該 Action 里的所有方法都有效。2 方法級 Result 映射：將多個Result 組成數(shù)組后作為Action 的 results 屬性值。這種 Result 映射僅對被修飾的方法有效。5)ResultPath 則用于修飾包和 Action 類，用于改變被修飾 Action 所對應的物理視圖資源的根路徑。舉例說：默認情況下，Convention 都會到 WE

15、B-INF/content 路徑下找物理視圖資源，一旦我們使用ResultPath(/abc)修飾 t裝Action,系統(tǒng)將回到 abc 目錄下尋找物理視圖資源。舉例：在默認情況下，Convention 都會到 WEB-INF/content 路徑下需找物理視圖資源，一旦我們使用Res3tPath(/abc)修飾亥Action,系統(tǒng)會到 abc 目錄下尋找物理視圖資源。9 與包和命名空間相關的 Annotation:Namespace：修夕 AAction 類或其所在的包。該 Annotation 中指定一個 value 屬性值，用于指定被修飾的 Action 所在的命名空間Namespace

16、s：修飾 Action 類或其所在的包，用于組合多個NamespaceParentPackage:用于指定被修飾的 Action 所在包的父包。10 異常處理相關的 AnnotationExceptionMappings 用于組織多個ExceptionMapping,因此它只需指定一個 value 屬性值，該value 屬性值為多個ExceptionMapping。ExceptionMapping 用于定義異常類和物理視圖之間的對應關系，也相當于 struts.xml 文件里元素的作用使用時，必須注意以下兩個屬性：exception:用于指定異常類result:用于指定邏輯視圖Exceptio

17、nMpping 有如下兩種用法Action 級的異常定義：以ExceptionMappings 組合多個ExceptionMapping 后修 1的 Action 類。這種異常定義對 Action 中的所有方法有效方法級的異常定義：將多個ExceptionMapping 組成數(shù)組后作為Action 的 exceptionMappings 屬性值，這種異常定義僅對被修飾的方法有效。11.攔截器配置相關的 Annotation與攔截器配置的 Annotation 有InterceptorRef、InterceptorRefs 和DefaultInterceptorRefInterceptorRef

18、s 用于組織多個InterceptorRef,因此它只需要指定一個 value 屬性值，該 value屬性值為多個InterceptorRefInterceptorRef 用于為指定 Action 引用 lanjieq 或者是攔截器棧。也就相當于 strut.xml 中位于元素內部的子元素的作用。使用InterceptorRefAnnotation 時，必須制定一個 value 屬性，用于指定所引用的攔截器或攔截器棧的名字。相當于子元素里 name 屬性的作用。IntroductionTheConventionPluginisbundledwithStrutssince2.1andreplac

19、estheZeroConfigplugins.Itprovidesthefollowingfeatures:ActionlocationbypackagenamingconventionsResult(JSP,FreeMarker,etc)locationbynamingconventionsClassnametoURLnamingconventionPackagenametonamespaceconventionSEOcompliantURLs(i.e.my-actionratherthanMyAction)ActionnameoverridesusingannotationsInterce

20、ptoroverridesusingannotationsNamespaceoverridesusingannotationsXWorkpackageoverridesusingannotationsDefaultactionandresulthandling(i.e./productswilltrycom.example.actions.Pducts.Index)TheConventionPluginshouldrequirenoconfigurationtouse.Manyoftheconventionscanbe

21、controlledusingconfigurationpropertiesandmanyoftheclassescanbeextendedoroverridden.CodebehindPluginandSetupInordertousetheConventionplugin,youfirstneedtoaddtheJARfiletotheWEB-INF/libdirectoryofyourapplication(ifyoupackageyouractionsinjarfiles,makesurethatstruts.convention.action.disableJarScanningis

22、settotrue).HelloworldNowthattheConventionpluginhasbeenaddedtoyourapplication,letsstartwithaverysimpleexample.ThisexamplewilluseanactionlessresultthatisidentifiedbytheURL.Bydefault,theConventionpluginassumesthatalloftheresultsarestoredinWEB-INF/content.Thiscanbechangedbysettingthepropertystruts.conve

23、ntion.result.pathintheStrutspropertiesfiletothenewlocation.Dontworryabouttrailingslashes,theConventionpluginhandlesthisforyou.HereisourhelloworldJSP:WEB-INF/content/hello-world.jspHelloworld!IfyoustartTomcat(orwhicheverJ2EEcontaineryouareusing)andtypeinhttp:/localhost:8080/hello-worldintoyourbrowser

24、youshouldgetthisresult:WEB-INF/content/hello-world.jspHelloworld!ThisillustratesthattheConventionpluginwillfindresultsevenwhennoactionexistsanditisallbasedontheURLpassedtoStruts.CodebehindhelloworldLetsexpandonthisexampleandaddacodebehindclass.InordertodothisweneedtoensurethattheConventionpluginisab

25、letofindouractionclasses.Bydefault,theConventionpluginwillfindallactionclassesthatimplementcom.opensymphony.xwork2.ActionorwhosenameendswiththewordActioninspecificpackages.ThesepackagesarelocatedbytheConventionpluginusingasearchmethodology.FirsttheConventionpluginfindspackagesnamedstruts,struts2,act

26、ionoractions.AnypackagesthatmatchthosenamesareconsideredtherootpackagesfortheConventionplugin.Next,thepluginlooksatalloftheclassesinthosepackagesaswellassub-packagesanddeterminesiftheclassesimplementcom.opensymphony.xwork2.ActionoriftheirnameendswithAction(i.e.FooAction).Heresanexampleofafewclassest

27、hattheConventionpluginwillfind:Classescom.example.actions.MainAducts.Display(implementscom.opensymphony.xwork2.Action)pany.details.ShowCompanyDetailsActionEachoftheactionclassesthatthepluginfindswillbeconfiguredtorespondtospecificURLs.TheURLisbasedonthepackagenamethatthec

28、lassisdefinedinandtheclassnameitself.FirsttheplugindeterminesthenamespaceoftheURLusingthepackagenamesbetweentherootpackageandthepackagetheclassisdefinedin.Forourexamplesabove,thenamespaceswouldbe:Namespacescom.example.actions.MainAction-/ducts.Display-/pany.details.ShowCompany

29、DetailsAction-/company/detailsNext,theplugindeterminestheURLoftheresourceusingtheclassname.ItfirstremovesthewordActionfromtheendoftheclassnameandthenconvertscamelcasenamestodashes.InourexamplethefullURLswouldbe:FullURLscom.example.actions.MainAction-/ducts.Display-/product

30、s/pany.details.ShowCompanyDetailsAction-/company/details/show-company-detailsYoucantelltheConventionplugintoignorecertainpackagesusingthepropertystruts.convention.exclude.packages.Youcanalsotelltheplugintousedifferentstringstolocaterootpackagesusingthepropertystruts.convention.package.locators.Final

31、ly,youcantelltheplugintosearchspecificrootpackagesusingthepropertystruts.convention.action.packages.Hereisourcodebehindactionclass:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;publicclassHelloWorldextendsActionSupportprivateStringmessage;public

32、StringgetMessage()returnmessage;publicStringexecute()message=HelloWorld!;returnSUCCESS;IfyoucompilethisclassandplaceitintoyourapplicationintheWEB-INF/classes,theConventionpluginwillfindtheclassandmaptheURL/hello-worldtoit.Next,weneedtoupdateourJSPtoprintoutthemessagewesetupintheactionclass.Hereisthe

33、newJSP:WEB-INF/content/hello-world.jspThemessageis$messageIfstartuptheapplicationserverandopenuphttp:/localhost:8080/hello-worldinourbrowser,weshouldgetthisresult:ResultThemessageisHelloWorld!ResultsandresultcodesTheConventionPluginwillpre-configureallofyouactionclasseswhenStrutsisstarted.Bydefault,

34、thisconfigurationwillalsocontainresultsforanyJSPsthatitcanfindwithintheapplication.TheJSPshaveanadditionalfeaturethatallowsdifferentJSPstobeusedbasedontheresultcodeoftheaction.SinceactionmethodsreturnStringsandtheseStringsaretraditionallyusedtolocateresultsfortheaction,theConventionpluginallowsyouto

35、definedifferentresultsbasedontheresultcode.Buildingonourexamplefromabove,letssaywewanttoprovideadifferentresultiftheresultcodefromouractionistheStringzeroratherthansuccess.First,weupdatetheactionclasstoreturndifferentresultcodes:com.example.actions.HelloWorldpackagecom.example.actions;importcom.open

36、symphony.xwork2.ActionSupport;publicclassHelloWorldextendsActionSupportprivateStringmessage;publicStringgetMessage()returnmessage;publicStringexecute()if(System.currentTimeMillis()%2=0)message=Its0;returnzero;message=Its1;returnSUCCESS;Next,weaddanewJSPtotheapplicationnamedWEB-INF/content/hello-worl

37、d-zero.jspNoticethatthefirstpartofthefilenameisthesameastheURLoftheactionandthelastpartofthenameistheresultcode.Thisistheconventionthatthepluginusestodeterminewhichresultstorender.HereisournewJSP:WEB-INF/content/hello-world.jspTheerrormessageis$messageNow,ifyoucompiletheactionandrestarttheapplicatio

38、n,basedonthecurrenttime,youlleitherseetheresultfromWEB-INF/content/hello-world.jsporWEB-INF/content/hello-world-zero.jsp.Theresulttypeisbasedontheextensionofthefile.Thesupportedextensionsare:jsp,ftl,vm,html,html.ExamplesofActionandResulttoTemplatemapping:URLResultFilethatcouldmatchResultType/hellosu

39、ccess/WEB-INF/content/hello.jspDispatcher/hellosuccess/WEB-INF/content/hello-success.htmDispatcher/hellosuccess/WEB-INF/content/hello.ftlFreeMarker/hello-worldinput/WEB-INF/content/hello-world-input.vmVelocity/test1/test2/helloerror/WEB-INF/content/test/test2/hello-error.htmlDispatcherChainingIfonea

40、ctionreturnsthenameofanotheractioninthesamepackage,theywillbechainedtogether,ifthefirstactiondoesnthaveanyresultdefinedforthatcode.Inthefollowingexample:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.Action;importcom.opensymphony.xwork2.ActionSupport;publiccla

41、ssHelloActionextendsActionSupportAction(foo)publicStringfoo()returnbar;)Action(foo-bar)publicStringbar()returnSUCCESS;)Thefooactionwillbeexecuted,becausenoresultisfound,theConventionplugintriestofindanactionnamedfoo-baronthesamepackagewherefooisdefined.Ifsuchanactionisfound,itwillbeinvokedusingthech

42、ainresult.XWorkpackagesActionsareplacedonacustomXWorkpackagewhichpreventsconflicts.ThenameofthispackageisbasedontheJavapackagetheactionisdefinedin,thenamespacepartoftheURLfortheactionandtheparentXWorkpackagefortheaction.TheparentXWorkpackageisdeterminedbasedonthepropertynamedstruts.convention.defaul

43、t.parent.package(defaultstoconventionDefault),whichisacustomXWorkpackagethatextendsstrutsDefaultThereforethenamingforXWorkpackagesusedbytheConventionpluginareintheform:XWorkpackagenaming#Usingourexamplefromabove,theXWorkpackageforouractionwouldbe:XWorkpackagenamingcom.example.actions#/#conventionDef

44、aultAnnotationreferenceTheConventionpluginusesanumberofdifferentannotationstooverridethedefaultconventionsthatareusedtomapactionstoURLsandlocateresults.Inaddition,youcanmodifytheparentXWorkpackagethatactionsareconfiguredwith.ActionannotationTheConventionpluginallowsactionclassestochangetheURLthatthe

45、yaremappedtousingtheActionannotation.ThisannotationcanalsobeusedinsidetheActionsannotationtoallowmultipleURLstomaptoasingleactionclass.Thisannotationmustbedefinedonactionmethodslikethis:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;importorg.apa

46、che.struts2.convention.annotation.Action;publicclassHelloWorldextendsActionSupportAction(/different/url)publicStringexecute()returnSUCCESS;OuractionclasswillnowmaptotheURL/different/urlratherthan/hello-world.IfnoResult(seenextsection)isspecified,thenthenamespaceoftheactionwillbeusedasthepathtotheres

47、ult,onourlastexampleitwouldbe/WEB-INF/content/different/url.jsp”.AsinglemethodwithinanactionclasscanalsomaptomultipleURLsusingthelikethis:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;importorg.apache.struts2.convention.annotation.Action;importo

48、rg.apache.struts2.convention.annotation.Actions;Actions(ActionsannotationpublicclassHelloWorldextendsActionSupportAction(/different/url),Action(/another/url)publicStringexecute()returnSUCCESS;)AnotherusageoftheActionorActionsannotationistodefinemultipleactionmethodswithinasingleactionclass,eachofwhi

49、chrespondtoadifferentURL.Hereisanexampleofmultipleactionmethods:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;importorg.apache.struts2.convention.annotation.Action;importorg.apache.struts2.convention.annotation.Actions;publicclassHelloWorldexten

50、dsActionSupportAction(/different/url)publicStringexecute()returnSUCCESS;)Action(url)publicStringdoSomething()returnSUCCESS;)ThepreviousexampledefinesasecondURLthatisnotfullyqualified.ThismeansthatthenamespacefortheURLisdeterminedusingtheJavapackagenameratherthantheActionannotation.Interceptorandinte

51、rceptorstackscanbespecifiedusingtheinterceptorRefsattribute.ThefollowingexampleappliesthevalidationinterceptorandthedefaultStackinterceptorstacktotheaction:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;importorg.apache.struts2.convention.annotat

52、ion.Action;importorg.apache.struts2.convention.annotation.Actions;publicclassHelloWorldextendsActionSupportAction(interceptorRefs=InterceptorRef(validation),InterceptorRef(defaultStack)publicStringexecute()returnSUCCESS;Action(url)publicStringdoSomething()returnSUCCESS;Parameterscanbepassedtoresults

53、usingtheparamsattribute.Thevalueofthisattributeisastringarraywithanevennumberofelementsintheformkey0,value0,key1,value1.keyN,valueN.Forexample:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;importorg.apache.struts2.convention.annotation.Action;im

54、portorg.apache.struts2.convention.annotation.Actions;publicclassHelloWorldextendsActionSupportAction(interceptorRefs=InterceptorRef(value=validation,params=programmatic,false,declarative,true)publicStringexecute()returnSUCCESS;Action(url)publicStringdoSomething()returnSUCCESS;Ifinterceptorsarenotspe

55、cified,thedefaultstackisapplied.InterceptorRefannotationInterceptorscanbespecifiedatthemethodlevel,usingtheActionannotationorattheclasslevelusingtheInterceptorRefsannotation.Interceptorsspecifiedattheclasslevelwillbeappliedtoallactionsdefinedonthatclass.Inthefollowingexample:com.example.actions.Hell

56、oWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;importorg.apache.struts2.convention.annotation.Action;importorg.apache.struts2.convention.annotation.Actions;InterceptorRefs(InterceptorRef(interceptor-1InterceptorRef(defaultStack)publicclassHelloWorldextendsAction(value=a

57、ction1,interceptorRefs=InterceptorRef(publicStringexecute()returnSUCCESS;Action(value=action2)publicStringdoSomething()returnSUCCESS;Thefollowinginterceptorswillbeappliedtoactionl:interceptor-1”,allinterceptorsfromdefaultstack,validation.Allinterceptorsfromdefaultstackwillbeappliedtoaction2.),)Actio

58、nSupportvalidation)ResultannotationTheConventionpluginallowsactionclassestodefinedifferentresultsforanaction.Resultsfallintotwocategories,globalandlocal.Globalresultsaresharedacrossallactionsdefinedwithintheactionclass.Theseresultsaredefinedasannotationsontheactionclass.Localresultsapplyonlytotheact

59、ionmethodtheyaredefinedon.Hereisanexampleofthedifferenttypesofresultannotations:com.example.actions.HelloWorldpackagecom.example.actions;importcom.opensymphony.xwork2.ActionSupport;importorg.apache.struts2.convention.annotation.Action;importorg.apache.struts2.convention.annotation.Actions;importorg.

60、apache.struts2.convention.annotation.Result;importorg.apache.struts2.convention.annotation.Results;Results(Result(name=failure,location=fail.jsp)publicclassHelloWorldextendsActionSupportAction(value=/different/url,results=Result(name=success,location=,type=redirect)publicStrin