spring与其它框架集成

1. Chapter14.Integratingwithotherwebframeworks
2. 14.1.Introduction
3. SpringcanbeeasilyintegratedintoanyJava-basedwebframework.AllyouneedtodoistodeclaretheContextLoaderListenerinyourweb.xmlanduseacontextConfigLocation<context-param>tosetwhichcontextfilestoload.
5. The<context-param>:
7. <context-param>
8. <param-name>contextConfigLocation</param-name>
9. <param-value>/WEB-INF/applicationContext*.xml</param-value>
10. </context-param>
11. The<listener>:
13. <listener>
14. <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
15. </listener>
16. NOTE:ListenerswereaddedtotheServletAPIinversion2.3.IfyouhaveaServlet2.2container,youcanusetheContextLoaderServlettoachievethissamefunctionality.
18. Ifyoudon'tspecifythecontextConfigLocationcontextparameter,theContextLoaderListenerwilllookfora/WEB-INF/applicationContext.xmlfiletoload.Oncethecontextfilesareloaded,SpringcreatesaWebApplicationContextobjectbasedonthebeandefinitionsandputsitintotheServletContext.
20. AllJavawebframeworksarebuiltontopoftheServletAPI,soyoucanusethefollowingcodetogettheApplicationContextthatSpringcreated.
22. WebApplicationContextctx=WebApplicationContextUtils.getWebApplicationContext(servletContext);
23. TheWebApplicationContextUtilsclassisforconvenience,soyoudon'thavetorememberthenameoftheServletContextattribute.ItsgetWebApplicationContext()methodwillreturnnullifanobjectdoesn'texistundertheWebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTEkey.RatherthanriskgettingNullPointerExceptionsinyourapplication,it'sbettertousethegetRequiredWebApplicationContext()method.ThismethodthrowsanExceptionwhentheApplicationContextismissing.
25. OnceyouhaveareferencetotheWebApplicationContext,youcanretrievebeansbytheirnameortype.Mostdevelopersretrievebeansbyname,thencastthemtooneoftheirimplementedinterfaces.
27. Fortunately,mostoftheframeworksinthissectionhavesimplerwaysoflookingupbeans.NotonlydotheymakeiteasytogetbeansfromtheBeanFactory,buttheyalsoallowyoutousedependencyinjectionontheircontrollers.Eachframeworksectionhasmoredetailonitsspecificintegrationstrategies.
29. 14.2.JavaServerFaces
30. JavaServerFaces(JSF)isacomponent-based,event-drivenwebframework.AccordingtoSunMicrosystem'sJSFOverview,JSFtechnologyincludes:
32. AsetofAPIsforrepresentingUIcomponentsandmanagingtheirstate,handlingeventsandinputvalidation,definingpagenavigation,andsupportinginternationalizationandaccessibility.
34. AJavaServerPages(JSP)customtaglibraryforexpressingaJavaServerFacesinterfacewithinaJSPpage.
36. 14.2.1.DelegatingVariableResolver
37. TheeasiestwaytointegrateyourSpringmiddle-tierwithyourJSFweblayeristousetheDelegatingVariableResolverclass.Toconfigurethisvariableresolverinyourapplication,you'llneedtoedityourfaces-context.xml.Aftertheopening<faces-config>element,addan<application>elementanda<variable-resolver>elementwithinit.ThevalueofthevariableresolvershouldreferenceSpring'sDelegatingVariableResolver:
39. <faces-config>
40. <application>
41. <variable-resolver>org.springframework.web.jsf.DelegatingVariableResolver</variable-resolver>
42. <locale-config>
43. <default-locale>en</default-locale>
44. <supported-locale>en</supported-locale>
45. <supported-locale>es</supported-locale>
46. </locale-config>
47. <message-bundle>messages</message-bundle>
48. </application>
49. ByspecifyingSpring'svariableresolver,youcanconfigureSpringbeansasmanagedpropertiesofyourmanagedbeans.TheDelegatingVariableResolverwillfirstdelegatevaluelookupstothedefaultresolveroftheunderlyingJSFimplementation,andthentoSpring'srootWebApplicationContext.ThisallowsyoutoeasilyinjectdependenciesintoyourJSF-managedbeans.
51. Managedbeansaredefinedinyourfaces-config.xmlfile.Belowisanexamplewhere#{userManager}isabeanthat'sretrievedfromSpring'sBeanFactory.
53. <managed-bean>
54. <managed-bean-name>userList</managed-bean-name>
55. <managed-bean-class>com.whatever.jsf.UserList</managed-bean-class>
56. <managed-bean-scope>request</managed-bean-scope>
57. <managed-property>
58. <property-name>userManager</property-name>
59. <value>#{userManager}</value>
60. </managed-property>
61. </managed-bean>
62. TheDelegatingVariableResolveristherecommendedstrategyforintegratingJSFandSpring.Ifyou'relookingformorerobustintegrationfeatures,youmighttakealookattheJSF-Springproject.
64. 14.2.2.FacesContextUtils
65. AcustomVariableResolverworkswellwhenmappingyourpropertiestobeansinfaces-config.xml,butattimesyoumayneedtogrababeanexplicitly.TheFacesContextUtilsclassmakesthiseasy.It'ssimilartoWebApplicationContextUtils,exceptthatittakesaFacesContextparameterratherthanaServletContextparameter.
67. ApplicationContextctx=FacesContextUtils.getWebApplicationContext(FacesContext.getCurrentInstance());
72. 14.3.Struts
73. StrutsisthedefactowebframeworkforJavaapplications,mainlybecauseitwasoneofthefirsttobereleased(June2001).InventedbyCraigMcClanahan,StrutsisanopensourceprojecthostedbytheApacheSoftwareFoundation.Atthetime,itgreatlysimplifiedtheJSP/Servletprogrammingparadigmandwonovermanydeveloperswhowereusingproprietaryframeworks.Itsimplifiedtheprogrammingmodel,itwasopensource,andithadalargecommunity,whichallowedtheprojecttogrowandbecomepopularamongJavawebdevelopers.
75. TointegrateyourStrutsapplicationwithSpring,youhavetwooptions:
77. ConfigureSpringtomanageyourActionsasbeans,usingtheContextLoaderPlugin,andsettheirdependenciesinaSpringcontextfile.
79. SubclassSpring'sActionSupportclassesandgrabyourSpring-managedbeansexplicitlyusingagetWebApplicationContext()method.
81. 14.3.1.ContextLoaderPlugin
82. TheContextLoaderPluginisaStruts1.1+plug-inthatloadsaSpringcontextfilefortheStrutsActionServlet.ThiscontextreferstotherootWebApplicationContext(loadedbytheContextLoaderListener)asitsparent.Thedefaultnameofthecontextfileisthenameofthemappedservlet,plus-servlet.xml.IfActionServletisdefinedinweb.xmlas<servlet-name>action</servlet-name>,thedefaultis/WEB-INF/action-servlet.xml.
84. Toconfigurethisplug-in,addthefollowingXMLtotheplug-inssectionnearthebottomofyourstruts-config.xmlfile:
86. <plug-inclassName="org.springframework.web.struts.ContextLoaderPlugIn"/>
87. Thelocationofthecontextconfigurationfilescanbecustomizedusingthe"contextConfigLocation"property.
91. <plug-inclassName="org.springframework.web.struts.ContextLoaderPlugIn">
92. <set-propertyproperty="contextConfigLocation"
93. value="/WEB-INF/action-servlet.xml.xml,/WEB-INF/applicationContext.xml"/>
94. </plug-in>
97. Itispossibletousethisplugintoloadallyourcontextfiles,whichcanbeusefulwhenusingtestingtoolslikeStrutsTestCase.StrutsTestCase'sMockStrutsTestCasewon'tinitializeListenersonstartupsoputtingallyourcontextfilesinthepluginisaworkaround.Abughasbeenfiledforthisissue.
99. Afterconfiguringthisplug-ininstruts-config.xml,youcanconfigureyourActiontobemanagedbySpring.Spring1.1.3providestwowaystodothis:
101. OverrideStruts'defaultRequestProcessorwithSpring'sDelegatingRequestProcessor.
103. UsetheDelegatingActionProxyclassinthetypeattributeofyour<action-mapping>.
105. BothofthesemethodsallowyoutomanageyourActionsandtheirdependenciesintheaction-context.xmlfile.ThebridgebetweentheActioninstruts-config.xmlandaction-servlet.xmlisbuiltwiththeaction-mapping's"path"andthebean's"name".Ifyouhavethefollowinginyourstruts-config.xmlfile:
107. <actionpath="/users".../>
108. YoumustdefinethatAction'sbeanwiththe"/users"nameinaction-servlet.xml:
110. <beanname="/users".../>
111. 14.3.1.1.DelegatingRequestProcessor
112. ToconfiguretheDelegatingRequestProcessorinyourstruts-config.xmlfile,overridethe"processorClass"propertyinthe<controller>element.Theselinesfollowthe<action-mapping>element.
114. <controller>
115. <set-propertyproperty="processorClass"
116. value="org.springframework.web.struts.DelegatingRequestProcessor"/>
117. </controller>
119. Afteraddingthissetting,yourActionwillautomaticallybelookedupinSpring'scontextfile,nomatterwhatthetype.Infact,youdon'tevenneedtospecifyatype.Bothofthefollowingsnippetswillwork:
121. <actionpath="/user"type="com.whatever.struts.UserAction"/>
122. <actionpath="/user"/>
123. Ifyou'reusingStruts'modulesfeature,yourbeannamesmustcontainthemoduleprefix.Forexample,anactiondefinedas<actionpath="/user"/>withmoduleprefix"admin"requiresabeannamewith<beanname="/admin/user"/>.
125. NOTE:Ifyou'reusingTilesinyourStrutsapplication,youmustconfigureyour<controller>withtheDelegatingTilesRequestProcessor.
127. 14.3.1.2.DelegatingActionProxy
128. IfyouhaveacustomRequestProcessorandcan'tusetheDelegatingTilesRequestProcessor,youcanusetheDelegatingActionProxyasthetypeinyouraction-mapping.
130. <actionpath="/user"type="org.springframework.web.struts.DelegatingActionProxy"
131. name="userForm"scope="request"validate="false"parameter="method">
132. <forwardname="list"path="/userList.jsp"/>
133. <forwardname="edit"path="/userForm.jsp"/>
134. </action>
136. Thebeandefinitioninaction-servlet.xmlremainsthesame,whetheryouuseacustomRequestProcessorortheDelegatingActionProxy.
138. IfyoudefineyourActioninacontextfile,thefullfeaturesetofSpring'sbeancontainerwillbeavailableforit:dependencyinjectionaswellastheoptiontoinstantiateanewActioninstanceforeachrequest.Toactivatethelatter,addsingleton="false"toyourAction'sbeandefinition.
140. <beanname="/user"singleton="false"autowire="byName"
141. class="org.example.web.UserAction"/>
142. 14.3.2.ActionSupportClasses
143. Aspreviouslymentioned,youcanretrievetheWebApplicationContextfromtheServletContextusingtheWebApplicationContextUtilsclass.AneasierwayistoextendSpring'sActionclassesforStruts.Forexample,insteadofsubclassingStruts'Actionclass,youcansubclassSpring'sActionSupportclass.
145. TheActionSupportclassprovidesadditionalconveniencemethods,likegetWebApplicationContext().BelowisanexampleofhowyoumightusethisinanAction:
147. publicclassUserActionextendsDispatchActionSupport{
149. publicActionForwardexecute(ActionMappingmapping,
150. ActionFormform,
151. HttpServletRequestrequest,
152. HttpServletResponseresponse)
153. throwsException{
154. if(log.isDebugEnabled()){
155. log.debug("entering'delete'method...");
156. }
158. WebApplicationContextctx=getWebApplicationContext();
159. UserManagermgr=(UserManager)ctx.getBean("userManager");
161. //talktomanagerforbusinesslogic
163. returnmapping.findForward("success");
164. }
165. }
166. SpringincludessubclassesforallofthestandardStrutsActions-theSpringversionsmerelyhaveSupportappendedtothename:
168. ActionSupport,
170. DispatchActionSupport,
172. LookupDispatchActionSupportand
174. MappingDispatchActionSupport.
177. Therecommendedstrategyistousetheapproachthatbestsuitsyourproject.Subclassingmakesyourcodemorereadable,andyouknowexactlyhowyourdependenciesareresolved.However,usingtheContextLoaderPluginallowyoutoeasilyaddnewdependenciesinyourcontextXMLfile.Eitherway,Springprovidessomeniceoptionsforintegratingthetwoframeworks.
179. 14.4.Tapestry
180. Tapestryisapowerful,component-orientedwebapplicationframeworkfromApache'sJakartaproject(http://jakarta.apache.org/tapestry).WhileSpringhasitsownpowerfulwebuilayer,thereareanumberofuniqueadvantagestobuildingaJ2EEapplicationusingacombinationofTapestryforthewebui,andtheSpringcontainerforthelowerlayers.Thisdocumentattemptstodetailafewbestpracticesforcombiningthesetwoframeworks.ItisexpectedthatyouarerelativelyfamiliarwithbothTapestryandSpringFrameworkbasics,sotheywillnotbeexplainedhere.GeneralintroductorydocumentationforbothTapestryandSpringFrameworkareavailableontheirrespectivewebsites.
182. 14.4.1.Architecture
183. AtypicallayeredJ2EEapplicationbuiltwithTapestryandSpringwillconsistofatopUIlayerbuiltwithTapestry,andanumberoflowerlayers,hostedoutofoneormoreSpringApplicationContexts.
185. UserInterfaceLayer:
187. -concernedwiththeuserinterface
189. -containssomeapplicationlogic
191. -providedbyTapestry
193. -asidefromprovidingUIviaTapestry,codeinthislayerdoesitsworkviaobjectswhichimplementinterfacesfromtheServiceLayer.TheactualobjectswhichimplementtheseservicelayerinterfacesareobtainedfromaSpringApplicationContext.
195. ServiceLayer:
197. -applicationspecific'service'code
199. -workswithdomainobjects,andusestheMapperAPItogetthosedomainobjectsintoandoutofsomesortofrepository(database)
201. -hostedinoneormoreSpringcontexts
203. -codeinthislayermanipulatesobjectsinthedomainmodel,inanapplicationspecificfashion.Itdoesitsworkviaothercodeinthislayer,andviatheMapperAPI.Anobjectinthislayerisgiventhespecificmapperimplementationsitneedstoworkwith,viatheSpringcontext.
205. -sincecodeinthislayerishostedintheSpringcontext,itmaybetransactionallywrappedbytheSpringcontext,asopposedtomanagingitsowntransactions
207. DomainModel:
209. -domainspecificobjecthierarchy,whichdealswithdataandlogicspecifictothisdomain
211. -althoughthedomainobjecthierarchyisbuiltwiththeideathatitispersistedsomehowandmakessomegeneralconcessionstothis(forexample,bidirectionalrelationships),itgenerallyhasnoknowledgeofotherlayers.Assuch,itmaybetestedinisolation,andusedwithdifferentmappingimplementationsforproductionvs.testing.
213. -theseobjectsmaybestandalone,orusedinconjunctionwithaSpringapplicationcontexttotakeadvantageofsomeofthebenefitsofthecontext,e.g.,isolation,inversionofcontrol,differentstrategyimplementations,etc.
215. DataSourceLayer:
217. -MapperAPI(alsocalledDataAccessObjects):anAPIusedtopersistthedomainmodeltoarepositoryofsomesort(generallyaDB,butcouldbethefilesystem,memory,etc.)
219. -MapperAPIimplementations:oneormorespecificimplementationsoftheMapperAPI,forexample,aHibernate-specificmapper,aJDO-specificmapper,JDBC-specificmapper,oramemorymapper.
221. -mapperimplementationsliveinoneormoreSpringApplicationContexts.Aservicelayerobjectisgiventhemapperobjectsitneedstoworkwithviathecontext.
223. Database,filesystem,orotherrepositories:
225. -objectsinthedomainmodelarestoredintooneormorerepositoriesviaoneormoremapperimplementations
227. -arepositorymaybeverysimple(e.g.filesystem),ormayhaveitsownrepresentationofthedatafromthedomainmodel(i.e.aschemainadb).Itdoesnotknowaboutotherlayershowerver.
229. 14.4.2.Implementation
230. Theonlyrealquestion(whichneedstobeaddressedbythisdocument),ishowTapestrypagesgetaccesstoserviceimplementations,whicharesimplybeansdefinedinaninstanceoftheSpringApplicationContext.
232. 14.4.2.1.Sampleapplicationcontext
233. AssumewehavethefollowingsimpleApplicationContextdefinition,inxmlform:
235. <?xmlversion="1.0"encoding="UTF-8"?>
236. <!DOCTYPEbeansPUBLIC"-//SPRING//DTDBEAN//EN"
237. "http://www.springframework.org/dtd/spring-beans.dtd">
239. <beans>
241. <!--=========================GENERALDEFINITIONS=========================-->
243. <!--=========================PERSISTENCEDEFINITIONS=========================-->
245. <!--theDataSource-->
246. <beanid="dataSource"class="org.springframework.jndi.JndiObjectFactoryBean">
247. <propertyname="jndiName"><value>java:DefaultDS</value></property>
248. <propertyname="resourceRef"><value>false</value></property>
249. </bean>
251. <!--defineaHibernateSessionfactoryviaaSpringLocalSessionFactoryBean-->
252. <beanid="hibSessionFactory"
253. class="org.springframework.orm.hibernate.LocalSessionFactoryBean">
254. <propertyname="dataSource"><refbean="dataSource"/></property>
255. </bean>
257. <!--
258. -Definesatransactionmanagerforusageinbusinessordataaccessobjects.
259. -Nospecialtreatmentbythecontext,justabeaninstanceavailableasreference
260. -forbusinessobjectsthatwanttohandletransactions,e.g.viaTransactionTemplate.
261. -->
262. <beanid="transactionManager"
263. class="org.springframework.transaction.jta.JtaTransactionManager">
264. </bean>
266. <beanid="mapper"
267. class="com.whatever.dataaccess.mapper.hibernate.MapperImpl">
268. <propertyname="sessionFactory"><refbean="hibSessionFactory"/></property>
269. </bean>
271. <!--=========================BUSINESSDEFINITIONS=========================-->
273. <!--AuthenticationService,includingtxinterceptor-->
274. <beanid="authenticationServiceTarget"
275. class="com.whatever.services.service.user.AuthenticationServiceImpl">
276. <propertyname="mapper"><refbean="mapper"/></property>
277. </bean>
278. <beanid="authenticationService"
279. class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
280. <propertyname="transactionManager"><refbean="transactionManager"/></property>
281. <propertyname="target"><refbean="authenticationServiceTarget"/></property>
282. <propertyname="proxyInterfacesOnly"><value>true</value></property>
283. <propertyname="transactionAttributes">
284. <props>
285. <propkey="*">PROPAGATION_REQUIRED</prop>
286. </props>
287. </property>
288. </bean>
290. <!--UserService,includingtxinterceptor-->
291. <beanid="userServiceTarget"
292. class="com.whatever.services.service.user.UserServiceImpl">
293. <propertyname="mapper"><refbean="mapper"/></property>
294. </bean>
295. <beanid="userService"
296. class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
297. <propertyname="transactionManager"><refbean="transactionManager"/></property>
298. <propertyname="target"><refbean="userServiceTarget"/></property>
299. <propertyname="proxyInterfacesOnly"><value>true</value></property>
300. <propertyname="transactionAttributes">
301. <props>
302. <propkey="*">PROPAGATION_REQUIRED</prop>
303. </props>
304. </property>
305. </bean>
307. </beans>
308. InsidetheTapestryapplication,weneedtoloadthisapplicationcontext,andallowTapestrypagestogettheauthenticationServiceanduserServicebeans,whichimplementtheAuthenticationServiceandUserServiceinterfaces,respectively.
310. 14.4.2.2.ObtainingbeansinTapestrypages
311. Atthispoint,theapplicationcontextisavailabletoawebapplicationbycallingSpring'sstaticutilityfunctionWebApplicationContextUtils.getApplicationContext(servletContext),whereservletContextisthestandardServletContextfromtheJ2EEServletspecification.Assuch,onesimplemechanismforapagetogetaninstanceoftheUserService,forexample,wouldbewithcodesuchas:
313. WebApplicationContextappContext=WebApplicationContextUtils.getApplicationContext(
314. getRequestCycle().getRequestContext().getServlet().getServletContext());
315. UserServiceuserService=(UserService)appContext.getBean("userService");
316. ...somecodewhichusesUserService
317. Thismechanismdoeswork.Itcanbemadealotlessverbosebyencapsulatingmostofthefunctionalityinamethodinthebaseclassforthepageorcomponent.However,insomerespectsitgoesagainsttheInversionofControlapproachwhichSpringencourages,whichisbeingusedinotherlayersofthisapp,inthatideallyyouwouldlikethepagetonothavetoaskthecontextforaspecificbeanbyname,andinfact,thepagewouldideallynotknowaboutthecontextatall.
319. Luckily,thereisamechanismtoallowthis.WerelyuponthefactthatTapestryalreadyhasamechanismtodeclarativelyaddpropertiestoapage,anditisinfactthepreferredapproachtomanageallpropertiesonapageinthisdeclarativefashion,sothatTapestrycanproperlymanagetheirlifecycleaspartofthepageandcomponentlifecycle.
321. 14.4.2.3.ExposingtheapplicationcontexttoTapestry
322. FirstweneedtomaketheApplicationContextavailabletotheTapestrypageorComponentwithouthavingtohavetheServletContext;thisisbecauseatthestageinthepage's/component'slifecyclewhenweneedtoaccesstheApplicationContext,theServletContextwon'tbeeasilyavailabletothepage,sowecan'tuseWebApplicationContextUtils.getApplicationContext(servletContext)directly.OnewayisbydefiningacustomversionoftheTapestryIEnginewhichexposesthisforus:
324. packagecom.whatever.web.xportal;
325. ...
326. import...
327. ...
328. publicclassMyEngineextendsorg.apache.tapestry.engine.BaseEngine{
330. publicstaticfinalStringAPPLICATION_CONTEXT_KEY="appContext";
332. /**
333. *@seeorg.apache.tapestry.engine.AbstractEngine#setupForRequest(org.apache.tapestry.request.RequestContext)
334. */
335. protectedvoidsetupForRequest(RequestContextcontext){
336. super.setupForRequest(context);
338. //insertApplicationContextinglobal,ifnotthere
339. Mapglobal=(Map)getGlobal();
340. ApplicationContextac=(ApplicationContext)global.get(APPLICATION_CONTEXT_KEY);
341. if(ac==null){
342. ac=WebApplicationContextUtils.getWebApplicationContext(
343. context.getServlet().getServletContext()
344. );
345. global.put(APPLICATION_CONTEXT_KEY,ac);
346. }
347. }
348. }
349. ThisengineclassplacestheSpringApplicationContextasanattributecalled"appContext"inthisTapestryapp's'Global'object.MakesuretoregisterthefactthatthisspecialIEngineinstanceshouldbeusedforthisTapestryapplication,withanentryintheTapestryapplicationdefinitionfile.Forexample:
351. file:xportal.application:
353. <?xmlversion="1.0"encoding="UTF-8"?>
354. <!DOCTYPEapplicationPUBLIC
355. "-//ApacheSoftwareFoundation//TapestrySpecification3.0//EN"
356. "http://jakarta.apache.org/tapestry/dtd/Tapestry_3_0.dtd">
357. <application
358. name="WhateverxPortal"
359. engine-class="com.whatever.web.xportal.MyEngine">
360. </application>
362. 14.4.2.4.Componentdefinitionfiles
363. Nowinourpageorcomponentdefinitionfile(*.pageor*.jwc),wesimplyaddproperty-specificationelementstograbthebeansweneedoutoftheApplicationContext,andcreatepageorcomponentpropertiesforthem.Forexample:
365. <property-specificationname="userService"
366. type="com.whatever.services.service.user.UserService">
367. global.appContext.getBean("userService")
368. </property-specification>
369. <property-specificationname="authenticationService"
370. type="com.whatever.services.service.user.AuthenticationService">
371. global.appContext.getBean("authenticationService")
372. </property-specification>
373. TheOGNLexpressioninsidetheproperty-specificationspecifiestheinitialvaluefortheproperty,asabeanobtainedfromthecontext.Theentirepagedefinitionmightlooklikethis:
375. <?xmlversion="1.0"encoding="UTF-8"?>
376. <!DOCTYPEpage-specificationPUBLIC
377. "-//ApacheSoftwareFoundation//TapestrySpecification3.0//EN"
378. "http://jakarta.apache.org/tapestry/dtd/Tapestry_3_0.dtd">
380. <page-specificationclass="com.whatever.web.xportal.pages.Login">
382. <property-specificationname="username"type="java.lang.String"/>
383. <property-specificationname="password"type="java.lang.String"/>
384. <property-specificationname="error"type="java.lang.String"/>
385. <property-specificationname="callback"type="org.apache.tapestry.callback.ICallback"persistent="yes"/>
386. <property-specificationname="userService"
387. type="com.whatever.services.service.user.UserService">
388. global.appContext.getBean("userService")
389. </property-specification>
390. <property-specificationname="authenticationService"
391. type="com.whatever.services.service.user.AuthenticationService">
392. global.appContext.getBean("authenticationService")
393. </property-specification>
395. <beanname="delegate"class="com.whatever.web.xportal.PortalValidationDelegate"/>
397. <beanname="validator"class="org.apache.tapestry.valid.StringValidator"lifecycle="page">
398. <set-propertyname="required"expression="true"/>
399. <set-propertyname="clientScriptingEnabled"expression="true"/>
400. </bean>
402. <componentid="inputUsername"type="ValidField">
403. <static-bindingname="displayName"value="Username"/>
404. <bindingname="value"expression="username"/>
405. <bindingname="validator"expression="beans.validator"/>
406. </component>
408. <componentid="inputPassword"type="ValidField">
409. <bindingname="value"expression="password"/>
410. <bindingname="validator"expression="beans.validator"/>
411. <static-bindingname="displayName"value="Password"/>
412. <bindingname="hidden"expression="true"/>
413. </component>
415. </page-specification>
417. 14.4.2.5.Addingabstractaccessors
418. NowintheJavaclassdefinitionforthepageorcomponentitself,allweneedtodoisaddanabstractgettermethodforthepropertieswehavedefined,toaccessthem.WhenthepageorcomponentisactuallyloadedbyTapestry,itperformsruntimecodeinstrumentationontheclassfiletoaddthepropertieswhichhavebeendefined,andhookuptheabstractgettermethodstothenewlycreatedfields.Forexample:
420. //ourUserServiceimplementation;willcomefrompagedefinition
421. publicabstractUserServicegetUserService();
422. //ourAuthenticationServiceimplementation;willcomefrompagedefinition
423. publicabstractAuthenticationServicegetAuthenticationService();
424. Forcompleteness,theentireJavaclass,foraloginpageinthisexample,mightlooklikethis:
426. packagecom.whatever.web.xportal.pages;
428. /**
429. *Allowstheusertologin,byprovidingusernameandpassword.
430. *Aftersuccessfullyloggingin,acookieisplacedontheclientbrowser
431. *thatprovidesthedefaultusernameforfuturelogins(thecookie
432. *persistsforaweek).
433. */
434. publicabstractclassLoginextendsBasePageimplementsErrorProperty,PageRenderListener{
436. /**thekeyunderwhichtheauthenticateduserobjectisstoredinthevisitas*/
437. publicstaticfinalStringUSER_KEY="user";
439. /**
440. *Thenameofacookietostoreontheuser'smachinethatwillidentify
441. *themnexttimetheylogin.
442. **/
443. privatestaticfinalStringCOOKIE_NAME=Login.class.getName()+".username";
444. privatefinalstaticintONE_WEEK=7*24*60*60;
446. //---attributes
448. publicabstractStringgetUsername();
449. publicabstractvoidsetUsername(Stringusername);
451. publicabstractStringgetPassword();
452. publicabstractvoidsetPassword(Stringpassword);
454. publicabstractICallbackgetCallback();
455. publicabstractvoidsetCallback(ICallbackvalue);
457. publicabstractUserServicegetUserService();
459. publicabstractAuthenticationServicegetAuthenticationService();
461. //---methods
463. protectedIValidationDelegategetValidationDelegate(){
464. return(IValidationDelegate)getBeans().getBean("delegate");
465. }
467. protectedvoidsetErrorField(StringcomponentId,Stringmessage){
468. IFormComponentfield=(IFormComponent)getComponent(componentId);
469. IValidationDelegatedelegate=getValidationDelegate();
470. delegate.setFormComponent(field);
471. delegate.record(newValidatorException(message));
472. }
474. /**
475. *Attemptstologin.
476. *
477. *<p>Iftheusernameisnotknown,orthepasswordisinvalid,thenanerror
478. *messageisdisplayed.
479. *
480. **/
481. publicvoidattemptLogin(IRequestCyclecycle){
483. Stringpassword=getPassword();
485. //Doalittleextraworktoclearoutthepassword.
487. setPassword(null);
488. IValidationDelegatedelegate=getValidationDelegate();
490. delegate.setFormComponent((IFormComponent)getComponent("inputPassword"));
491. delegate.recordFieldInputValue(null);
493. //Anerror,fromavalidationfield,mayalreadyhaveoccurred.
495. if(delegate.getHasErrors())
496. return;
498. try{
499. Useruser=getAuthenticationService().login(getUsername(),getPassword());
500. loginUser(user,cycle);
501. }
502. catch(FailedLoginExceptionex){
503. this.setError("Loginfailed:"+ex.getMessage());
504. return;
505. }
506. }
508. /**
509. *Setsupthe{@linkUser}astheloggedinuser,creates
510. *acookiefortheirusername(forsubsequentlogins),
511. *andredirectstotheappropriatepage,or
512. *aspecifiedpage).
513. *
514. **/
515. publicvoidloginUser(Useruser,IRequestCyclecycle){
517. Stringusername=user.getUsername();
519. //Getthevisitobject;thiswilllikelyforcethe
520. //creationofthevisitobjectandanHttpSession.
522. Mapvisit=(Map)getVisit();
523. visit.put(USER_KEY,user);
525. //Afterloggingin,gototheMyLibrarypage,unlessotherwise
526. //specified.
528. ICallbackcallback=getCallback();
530. if(callback==null)
531. cycle.activate("Home");
532. else
533. callback.performCallback(cycle);
535. //I'vefoundthatfailingtosetamaximumageandapathmeansthat
536. //thebrowser(IE5.0anyway)quietlydropsthecookie.
538. IEngineengine=getEngine();
539. Cookiecookie=newCookie(COOKIE_NAME,username);
540. cookie.setPath(engine.getServletPath());
541. cookie.setMaxAge(ONE_WEEK);
543. //Recordtheuser'susernameinacookie
545. cycle.getRequestContext().addCookie(cookie);
547. engine.forgetPage(getPageName());
548. }
550. publicvoidpageBeginRender(PageEventevent){
551. if(getUsername()==null)
552. setUsername(getRequestCycle().getRequestContext().getCookieValue(COOKIE_NAME));
553. }
554. }
556. 14.4.3.Summary
557. Inthisexample,we'vemanagedtoallowservicebeansdefinedintheSpringApplicationContexttobeprovidedtothepageinadeclarativefashion.Thepageclassdoesnotknowwheretheserviceimplementationsarecomingfrom,andinfactitiseasytoslipinanotherimplementation,forexample,duringtesting.ThisinversionofcontrolisoneoftheprimegoalsandbenefitsoftheSpringFramework,andwehavemanagedtoextenditallthewayuptheJ2EEstackinthisTapestryapplication.
559. 14.5.WebWork
560. WebWorkisawebframeworkdesignedwithsimplicityinmind.It'sbuiltontopofXWork,whichisagenericcommandframework.XWorkalsohasanIoCcontainer,butitisn'tasfull-featuredasSpringandwon'tbecoveredinthissection.WebWorkcontrollersarecalledActions,mainlybecausetheymustimplementtheActioninterface.TheActionSupportclassimplementsthisinterface,anditismostcommonparentclassforWebWorkactions.
562. WebWorkmaintainsitsownSpringintegrationproject,locatedonjava.netinthexwork-optionalproject.Currently,threeoptionsareavailableforintegratingWebWorkwithSpring:
564. SpringObjectFactory:overrideXWork'sdefaultObjectFactorysoXWorkwilllookforSpringbeansintherootWebApplicationContext.
566. ActionAutowiringInterceptor:useaninterceptortoautomaticallywireanAction'sdependenciesasthey'recreated.
568. SpringExternalReferenceResolver:lookupSpringbeansbasedonthenamedefinedinan<external-ref>elementofan<action>element.
570. AllofthesestrategiesareexplainedinfurtherdetailinWebWork'sDocumentation.
573. --------------------------------------------------------------------------------
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