A Stripes 15 Test Drive.docx

A Stripes 15 Test Drive.docx

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AStripes15TestDrive

AStripes1.5TestDrive

By FredericDaoud

01Dec2008|TheServerS

Stripesisasimpleandpowerfulaction-basedJavawebapplicationframework.Version1.5hasrecentlybeenreleasedwithlotsofcoolfeatures,sowhydon'twetakeitoutforatestdrive?

We'llgetatasteofhoweasyitistodevelopawebapplicationwithStripesbywritingasimpleexample,whereauserfillsoutaformtoregisterandthenlogsintoaccesstheapplication.

ActionBeans

ThefirstthingtoknowaboutStripesisthatyouwriteactionbeanstorespondtorequests.Actionbeansareso-calledbecausetheyencapsulatebothanaction（arequestthatoccurred）andoneormorebeans（referencestoyourmodeldata）.Intermsofcode,anactionbeanisaclassthatimplementstheActionBeaninterface:

publicinterfaceActionBean

{

publicActionBeanContextgetContext（）;

publicvoidsetContext（ActionBeanContextcontext）;

}

Justagetterandasetterfortheactionbeancontext,whichStripesautomaticallyprovidestoactionbeans.TheactionbeancontextcontainssuchinformationastheHttpServletRequestandHttpServletResponseobjects,theServletContext,theLocaleassociatedtothecurrentrequest,andsoon.WhileStripesdoesnotrequireyoutoworkdirectlywiththeseobjects,it'snicetoknowthattheyarethereforeasyaccessifyoudoneedthem.

Usually,you'llwanttoimplementtheActionBeaninterfaceonceandforallinabaseclass:

BaseActionBean.java

publicabstractclassBaseActionBeanimplementsActionBean

{

privateActionBeanContextcontext;

publicActionBeanContextgetContext（）

{

returncontext;

}

publicvoidsetContext（ActionBeanContextcontext）

{

this.context=context;

}

}

AllyourconcreteactionbeanscannowextendBaseActionBean.Thisalsogivesyouaplaceforcodethatyouwanttomakeavailabletoallyouractionbeans.

EventHandlers

Next,aneventhandlerisamethodinanactionbeanthatgetsinvokedbyStripestorespondtoarequest.Youcanhaveoneormoreeventhandlersinanactionbean.Therearenorestrictionsonthemethodnamenortheexceptionsthatitmaythrow.What'simportantisthatthemethodhavenoparametersandreturnaResolution（moreonresolutionsinaminute）,asin:

publicResolutiondoSomething（）{//...}

Eventhandlershaveaname,whichisthenameofthemethodbydefault（doSomethingintheexampleabove）.Youcanoverridethenamewiththe@HandlesEventannotation,asintheexamplebelowwheretheeventwillbenamedanotherName:

@HandlesEvent（"anotherName"）

publicResolutiondoSomething（）{//...}

Youuseeventhandlernamesinrequest-triggeringelementssuchaslinksandformsubmitbuttons.Forexample,youcancreatealinkthatinvokesthedoSomethingeventdefinedintheorg.stripesbook.article.action.SomeActionBeanclasswiththiscodeinyourJSP:

linkbeanclass="org.stripesbook.article.action.SomeActionBean"event="doSomething">Clickme

link>

Here'stheequivalentforaformsubmitbutton:

formbeanclass="org.stripesbook.article.action.SomeActionBean"><%--forminputcontrols...--%>

submitname="doSomething"value="Pressme"/>

form>

Noticehowclearandsimplethatis.Thefullyqualifiedclassnameoftheactionbeanandthenameoftheeventhandlermethodarerightthere.Noguesswork,andnoconfigurationfiles.

Resolutions

AresolutionisreturnedbyaneventhandlertotellStripeswheretogonexttoproducearesponsetotheclient.Resolutionisasimpleinterface:

publicinterfaceResolution

{

voidexecute（HttpServletRequestrequest,HttpServletResponseresponse）throwsException;

}

Stripesprovidesafewready-to-useimplementations.ThemostcommonlyusedisprobablytheForwardResolution,whichforwardstherequesttoaviewtemplate,suchasaJSP:

returnnewForwardResolution（"/path/to/your.jsp"）;

（Note:

I'musingJSPinthisarticle,butStripesworksequallywellwithFreeMarker.）

Youcanalsoforwardtoanotheractionbeanandevent:

returnnewForwardResolution（SomeActionBean.class,"doSomething"）;

Again,youcanseehowclearitistohavethepathtotheJSPortheactionbeanclassandmethodnamerightthereinsteadofburiedinaconfigurationfile.

StripesalsoincludesRedirectResolutiontoredirecttherequest,StreamingResolutiontostreamdatabacktotheclient,JavaScriptResolutiontoreturndataasaJavaScriptobject,andErrorResolutiontoreturnanHTTPerrorcode.

ATypicalRegister-Activate-LoginExample

That'senoughtheory.Let'stakeStripesoutforatestdrivebybuildingasimpleregister-activate-loginexample.Ausermustfirstregister,thenactivatetheaccountwithanactivationcode（normallysentbyemailtoconfirmthattheaddressisvalid,butwe'lljustuseahardcodedactivationcodeforthisexample）,andfinallylogintoenterthesecuredareaoftheapplication,asillustratedbelow.

We'llstartwithasimplemodel,theUserclass:

User.java

packageorg.stripesbook.article.model;

publicclassUser{

privateStringemail;

privateStringusername;

privateStringpassword;

privateStringactivationCode;

privatebooleanactivated;

/*Gettersandsetters...*/

}

Next,let'sbuildtheregistrationpage.

TheRegistrationPage

Theregistrationpageiswheretheusercreatesanaccount.Here'sascreenshotofthepage:

We'llstartbywritingtheactionbeanformanagingregistration,RegisterActionBean.java:

RegisterActionBean.java

packageorg.stripesbook.article.action;

@UrlBinding（"/register"）

publicclassRegisterActionBeanextendsBaseActionBean

{

privateUseruser;

privateStringconfirmPassword;

/*GettersandsettersforuserandconfirmPassword*/

@DefaultHandler

publicResolutionview（）

{

returnnewForwardResolution（"/WEB-INF/jsp/register.jsp"）;

}

publicResolutionregister（）

{

//Setrandomactivationcode;we'lljusthardcodeavalueforthisexampleuser.setActivationCode（"A1B2"）;//Savetheusertothe"database"Database.addUser（user）;

returnnewRedirectResolution（ActivateActionBean.class）.addParameter（"user.username",user.getUsername（））;}

publicUsergetUser（）{

returnuser;

}

publicvoidsetUser（Useruser）{

this.user=user;}

publicStringgetConfirmPassword（）

{returnconfirmPassword;}

publicvoidsetConfirmPassword（StringconfirmPassword）{this.confirmPassword=confirmPassword;}

Withthe@UrlBindingthatwedefined,wecanaccesstheregistrationpagewith[http:

//localhost:

8080/stripes-article/register].Thattargetstheactionbean'sdefaulteventhandler,whichisviewbecauseitisannotatedwith@DefaultHandler.Themethodforwardstoregister.jsp,whichdisplaystheregistrationform.

Here'swhattheinterestingpartoftheJSPfortheregistrationpagelookslike:

register.jsp

<%@taglibprefix="s"uri="%>

formbeanclass="org.stripesbook.article.action.RegisterActionBean">

Email:

textname="user.email"/>

Username:

textname="user.username"/>

Password:

passwordname="user.password"/>

Confirmpassword:

passwordname="confirmPassword"/>

submitname="register"value="Register"/>

form>

Ifyou'veregisteredbuthaven'tactivatedyouraccount,

linkbeanclass="org.stripesbook.article.action.ActivateActionBean">clickhere

link>

Ifyouraccountisalreadyactive,youcanproceedto

linkbeanclass="org.stripesbook.article.action.LoginActionBean">login

link>

NoticethedeclarationoftheStripestaglibraryatthetop.Next,wehaveaformwiththefourtextfieldsforenteringtheemail,username,password,andpasswordconfirmation.Thevaluesenteredbytheuserareboundtothecorrespondingpropertiesintheactionbean,accordingtoeachfield'sname=attribute.Thisworksevenfornestedproperties,suchasuser.email.StripeswillbindthevaluebycallinggetUser（）.setEmail（value）ontheactionbeanandwillevencreateanewUserobjectautomatically.YoujustdeclarethepropertiesintheactionbeanwithoutworryingaboutdreadedNullPointerExceptions.

Sincethename=ofthe

submit>buttonisregister,Stripesinvokesregister（）whentheuserpressestheRegisterbutton.Thatcreatestheuserinthedatabaseandredirectstotheactivationpage.

Beforegoinganyfurther,let'sdiscusshowweaddsomevalidationtotheregistrationpage.

Validation

Let'saddthesevalidationstotheregistrationform:

∙Allfieldsarerequired

∙Theemailmustbeinvalidemailaddressformat

∙Thepasswordandconfirmpasswordmustmatch.

Wecanachievethisquiteeasilywithvalidationannotationsontheuserfield:

RegisterActionBean.java

@ValidateNestedProperties（

{@Validate（field="email",required=true,converter=EmailTypeConverter.class）,

@Validate（field="username",required=true）,

@Validate（field="password",required=true,expression="${thiseqconfirmPassword}"）}）

privateUseruser;

Validationannotationsmustbeinanactionbean,butwecanstillvalidatefieldswithinamodelobjectbyusing@ValidateNestedPropertiesasinthecodeabove.Next,@Validatevalidatesafieldandhasbuilt-inelementsforcommontypesofvalidation.Hereweareusingrequired=truetomakeafieldrequired,andconverter=EmailTypeConverter.classtovalidatetheformatoftheemailaddress.Wecanvalidatethatthepasswordsmatchwith``expression="${thiseqconfirmPassword}",where``thisautomaticallyreferstothefieldbeingvalidated,andconfirmPasswordisthecorrespondingpropertyintheactionbean.ThesyntaxoftheexpressionisthesameasaregularJSPELexpression.

Notethatyoudon'thavetoworryaboutextraspacesatthebeginningorattheendofthein