stapler HTTP请求处理引擎开源项目

Staplerisalibrarythat"staples"yourapplicatioobjectstoURLs,makigiteasiertowritewebapplicatios.ThecoreideaofStapleristoautomaticallyassigURLsforyourobjects,creatigaituitiveURLhierarchy.

Normally,mostofyourJSPadservletgoeslikethis;first,youuseparametersadextrapathifotolocatetheobjecttoworkwith,theusesomemoreparametersadsuchtoperformsomeoperatiosagaistit(orperhapsrederHTML).Staplertakescareofthisfirstportiobydispatchigrequeststothatobjectyou'llbeworkigwith.

Supposeyouarebuildigawebapplicatiolikethesystemofjava.et,whereyougotprojects,mailiglists,documetsadfilessectio,adetc.ThefollowigfigureshowshowStaplerworks.

Thelefthalfshowsyourcode.OOPletsyoumodelthosecoceptsstraight-forwardlyitoclassesthatrefertoeachother.Throughreflectio,StaplerassigsURLstoyourapplicatioobjects.TherootofyourapplicatioobjectgetstherootURL /.Theobjectyoucaaccesswith root.getProject("stapler") wouldbeassigedtotheURL /project/stapler.Ithisway,yourobjectmodeldirectlytursitotheURLhierarchy,aspartiallyshowipurplearrows.

MostofthetimesJSPsareusedtoshowaobjectiyourapplicatio.StaplerallowsyoutoassociateJSPstoyourapplicatioclasses,asshowigreecirclesitheabovefigure.StaplerweavesthoseJSPsitotheURLhierarchy,adwhetheygetrequested,Staplersetsuptheevirometsuchthattheycaaccessthecorrespodigapplicatioobjectveryeasily,bythe"it"variable(like${it.ame}).

Similarly,ofteyouwattorusomeJavacodewheacertaiURLisrequested,asshowiredcirclesitheabovefigure.Forexample,whe /project/stapler/delete isrequested,you'dliketodeletetheprojectadredirecttheuserto /.WithStapler,thisisaseasyasdefiigamethodoyourapplicatioobjects.Staplerivokesthemethodotherightobject.

Servlet(adtechologieslikeJSP/JSFthatbuildsotopofit)caolybidrequestURLsitoyourstaticresources,JSPs,ad/orservletsiaverylimitedway.Youcaevetellthatfromthejava.etsystem.Forexample,theURLtoviewthearchiveofamailiglistis /servlets/SummarizeList?listName=aouce,theURLtosearchthearchiveif /servlets/SearchList?listName=aouce,adtheURLtomaageitis /servlets/MailigListEdit?list=aouce.

Thishassomeproblems.

Ordiaryservlet/JSPprevetsyoufromusigtheURLhierarchytoorgaizeyourapplicatio.Ithejava.etsystem,ifyouwattogeeratealikfromthearchivetothesearchpage,youhavetoputthewholeURLicludigalltheparameters.You'llbewritigsomethiglike /servlets/SearchList?list=${listName}.Asyourapplicatiogetsmorecomplicated,theumberofparameterswillicrease,makigyourapplicatioharderadhardertomaitai.

StaplerallowsyoutouseURLslike list/aouce/summarize, list/aouce/search,ad list/aouce/edit.Thusalikfromthesummarypagetothesearchissimply search.

Mostofthetimes,thefirstthigyourJSPsadservletseedtodoistolocatetheobjectthatyou'llbeworkigwith.Thisistedious.Eveworse,iteedstoberepeatedimayplaces.

Staplertakescareofthisforyou.WheyourJSPisivoked,youcaaccessthetargetobjectbythevariable"it".Orwheyouractiomethod(theequivaletoftheservlet)isivoked,itisivokedothetargetobject.Thiscutsdowalotofborigboiler-platecodeiyourapplicatio.

Servletsca'thadlerecursivedirectorystructureverywell.Itheabovefigure,Ihaverecursive Folder classthathastwoJSPseach.TheolywaytomakethisworkiservletistoassiguiqueIDstoeachfolderaddefiethoseJSPsatthetop-level.TheactualURLswillbeverydifferetfromtheaturaltreestructure.

StaplermapsthisveryaturallytoURLs.