JSF 源代码赏析之Lifecycle

JSF 源代码赏析之Lifecycle

关键字: jsf sourcecode lifecycle

JSF的生命周期在JSF应用中起着至关重要的作用，每一个JSF请求的处理都需要经过一次生命周期，本文从源码的角度分析JSF的生命周期。
在讨论生命周期之前，我们先要讨论FacesContext的一些元素，他们在整个生命周期中扮演了非常重要的角色。么个JSF应用必须保存它所处理的请求信息，FacesContext为处理请求和生成响应保存了所有必需的上下文信息，具体而言，它包括：
1.信息队列，MessageQueue，保存所有的消息
2.当前的组件树，ViewRoot，
3.外部上下文，ExternalContext
4.Application。
下面就是Sun的FacesContextImpl中的变量：

com.sun.faces.context.FacesContextImpl：

 //RelationshipInstanceVariables
 privateResponseStreamresponseStream=null;
 privateResponseWriterresponseWriter=null;
 privateExternalContextexternalContext=null;
 privateApplicationapplication=null;
 privateUIViewRootviewRoot=null;
 privateELContextelContext=null;
 privateRenderKitFactoryrkFactory;
 privateRenderKitlastRk;
 privateStringlastRkId;

 /**
 *StoremappingofclientIdtoArrayListofFacesMessage
 *instances.ThenullkeyisusedtorepresentFacesMessageinstances
 *thatarenotassociatedwithaclientIdinstance.
 */
 privateMap<String,List<FacesMessage>>componentMessageLists;
 //AttributeInstanceVariables

 privatebooleanrenderResponse=false;
 privatebooleanresponseComplete=false;

这里面有很多重要的对象值得我们去研究，按照从上到下的顺序，我们先来看看ExternalContext。
ExternalContext其实是对ServletContext（或PortletContext）的封装，提供了访问外部容器资源的各种方法，ExternalContext基类定义如下：

javax.faces.context.ExternalContext:

 publicabstractclassExternalContext{


 publicstaticfinalStringBASIC_AUTH="BASIC";
 publicstaticfinalStringCLIENT_CERT_AUTH="CLIENT_CERT";
 publicstaticfinalStringDIGEST_AUTH="DIGEST";
 publicstaticfinalStringFORM_AUTH="FORM";

 //----------------------------------------------------------PublicMethods
 publicabstractvoiddispatch(Stringpath)
 throwsIOException;
 publicabstractStringencodeActionURL(Stringurl);

 publicabstractStringencodeNamespace(Stringname);
 publicabstractStringencodeResourceURL(Stringurl);
 publicabstractStringgetAuthType();
  publicabstractObjectgetContext();
 publicabstractStringgetInitParameter(Stringname);
 publicabstractMapgetInitParameterMap();
 publicabstractStringgetRemoteUser();
 publicabstractObjectgetRequest();
 publicvoidsetRequest(Objectrequest){
 ExternalContextimpl;
 if(null!=(impl=(ExternalContext)this.getRequestMap().
 get("com.sun.faces.ExternalContextImpl"))){
 impl.setRequest(request);
 return;
 }

 thrownewUnsupportedOperationException();
 }
 publicvoidsetRequestCharacterEncoding(Stringencoding)throwsUnsupportedEncodingException{
 ExternalContextimpl;
 if(null!=(impl=(ExternalContext)this.getRequestMap().
 get("com.sun.faces.ExternalContextImpl"))){
 impl.setRequestCharacterEncoding(encoding);
 return;
 }
  thrownewUnsupportedOperationException();
 }
 publicabstractStringgetRequestContextPath();
 publicabstractLocalegetRequestLocale();
 publicabstractIterator<locale></locale>getRequestLocales();
 publicabstractIterator<string></string>getRequestParameterNames();
 publicabstractStringgetRequestPathInfo();
 publicabstractStringgetRequestServletPath();

 publicStringgetRequestCharacterEncoding(){
 ExternalContextimpl;
 if(null!=(impl=(ExternalContext)this.getRequestMap().
 get("com.sun.faces.ExternalContextImpl"))){
 //noinspectionTailRecursion
 returnimpl.getRequestCharacterEncoding();
 }
 thrownewUnsupportedOperationException();
 }

 publicStringgetRequestContentType(){
 ExternalContextimpl;
 if(null!=(impl=(ExternalContext)this.getRequestMap().
 get("com.sun.faces.ExternalContextImpl"))){
 //noinspectionTailRecursion
 returnimpl.getRequestContentType();
 }

 thrownewUnsupportedOperationException();
 }

 publicStringgetResponseCharacterEncoding(){
 ExternalContextimpl;
 if(null!=(impl=(ExternalContext)this.getRequestMap().
 get("com.sun.faces.ExternalContextImpl"))){
 //noinspectionTailRecursion
 returnimpl.getResponseCharacterEncoding();
 }
  thrownewUnsupportedOperationException();
 }

 publicStringgetResponseContentType(){
 ExternalContextimpl;
 if(null!=(impl=(ExternalContext)this.getRequestMap().
 get("com.sun.faces.ExternalContextImpl"))){
 //noinspectionTailRecursion
 returnimpl.getResponseContentType();
 }
 thrownewUnsupportedOperationException();
 }
 publicabstractURLgetResource(Stringpath)throwsMalformedURLException;
 publicabstractInputStreamgetResourceAsStream(Stringpath);
 publicabstractSet<string></string>getResourcePaths(Stringpath);
 publicabstractObjectgetResponse();
 publicabstractObjectgetSession(booleancreate);
 publicabstractPrincipalgetUserPrincipal();
 publicabstractbooleanisUserInRole(Stringrole);
 publicabstractvoidlog(Stringmessage,Throwableexception);
  publicabstractvoidredirect(Stringurl)throwsIOException;
 }

这个抽象类共有1000多行，提供了访问外部资源的各种方法，主要是对ServletContext或是PortletContext中方法的封装，比如getRemoteUser、getRequest、getSession等方法都是很常用的，但是在运用时也要注意，如果在程序中写死是ServletContext或HttpServletRequest，那么以后对于更换到Portal环境中是不利的，这个如果需要转换的话需要注意了。
下面来看看Application对象。Application对象是应用系统范围内的单例类，提供了对FacesContext文件的对象封装，从这个对象中可以得到很多FacesContext文件中的配置，还是来看看定义吧.

 //-------------------------------------------------------------Properties

 publicabstractActionListenergetActionListener();


 publicabstractvoidsetActionListener(ActionListenerlistener);


 publicabstractvoidsetDefaultLocale(Localelocale);

 publicabstractStringgetDefaultRenderKitId();


 publicabstractvoidsetDefaultRenderKitId(StringrenderKitId);

 publicabstractStringgetMessageBundle();


 publicabstractvoidsetMessageBundle(Stringbundle);


 publicabstractNavigationHandlergetNavigationHandler();


 publicabstractvoidsetNavigationHandler(NavigationHandlerhandler);


 publicabstractPropertyResolvergetPropertyResolver();



 publicResourceBundlegetResourceBundle(FacesContextctx,Stringname){
 Applicationapp=getRIApplicationImpl(ctx);
 if(app!=null){
 //noinspectionTailRecursion
 returnapp.getResourceBundle(ctx,name);
 }

 thrownewUnsupportedOperationException();
 }

 publicabstractVariableResolvergetVariableResolver();


 publicabstractvoidsetVariableResolver(VariableResolverresolver);


 publicvoidaddELResolver(ELResolverresolver){
 Applicationapp=getRIApplicationImpl();
 if(app!=null){
 app.addELResolver(resolver);
 }else{
 thrownewUnsupportedOperationException();
 }
 }

 publicELResolvergetELResolver(){
 Applicationapp=getRIApplicationImpl();
 if(app!=null){
 //noinspectionTailRecursion
 returnapp.getELResolver();
 }
 thrownewUnsupportedOperationException();
 }


 publicabstractViewHandlergetViewHandler();

 publicabstractvoidsetViewHandler(ViewHandlerhandler);

 publicabstractStateManagergetStateManager();

 publicabstractvoidsetStateManager(StateManagermanager);


 //-------------------------------------------------------ObjectFactories

 publicabstractvoidaddComponent(StringcomponentType,
 StringcomponentClass);


 publicabstractUIComponentcreateComponent(StringcomponentType)
 throwsFacesException;


 publicabstractUIComponentcreateComponent(ValueBindingcomponentBinding,
 FacesContextcontext,
 StringcomponentType)
 rowsFacesException;

 publicUIComponentcreateComponent(ValueExpressioncomponentExpression,
 FacesContextcontext,
 StringcomponentType)
 rowsFacesException{
 if(null==componentExpression||null==context||
 null==componentType){
 //PENDING-i18n
 StringBuilderbuilder=newStringBuilder(64);
 builder.append("nullparameters-");
 builder.append("componentExpression:").append(componentExpression);
 builder.append(",context:").append(context);
 builder.append(",componentType:").append(componentType);
 thrownewNullPointerException(builder.toString());
 }

 Objectresult;
 booleancreateOne=false;

 try{
 if(null!=(result=
 componentExpression.getValue(context.getELContext()))){
 //iftheresultisnotaninstanceofUIComponent
 createOne=(!(resultinstanceofUIComponent));
 //wehavetocreateone.
 }
 if(null==result||createOne){
 result=this.createComponent(componentType);
 componentExpression.setValue((context.getELContext()),result);
 }
 }catch(ELExceptionelex){
 thrownewFacesException(elex);
 }

 return(UIComponent)result;
 }


 publicabstractIterator<String>getComponentTypes();


 publicabstractvoidaddConverter(StringconverterId,

 publicabstractvoidaddConverter(ClasstargetClass,
 StringconverterClass);

 publicabstractConvertercreateConverter(StringconverterId);


 publicabstractConvertercreateConverter(ClasstargetClass);


 publicabstractIterator<String>getConverterIds();



 publicExpressionFactorygetExpressionFactory(){
 Applicationapp=getRIApplicationImpl();
 if(app!=null){
 //noinspectionTailRecursion
 returnapp.getExpressionFactory();
 }

 thrownewUnsupportedOperationException();
 }



 publicObjectevaluateExpressionGet(FacesContextcontext,
 Stringexpression,
 ClassexpectedType)throwsELException{
 Applicationapp=getRIApplicationImpl(context);
 if(app!=null){
 //noinspectionTailRecursion
 returnapp.evaluateExpressionGet(context,expression,expectedType);
 }
 thrownewUnsupportedOperationException();
 }

 publicabstractMethodBindingcreateMethodBinding(Stringref,
 Classparams[])
 throwsReferenceSyntaxException;

 publicabstractIterator<Locale>getSupportedLocales();


 publicabstractvoidsetSupportedLocales(Collection<Locale>locales);


 publicvoidaddELContextListener(ELContextListenerlistener){
 Applicationapp=getRIApplicationImpl();
 if(app!=null){
 app.addELContextListener(listener);
 }else{
 thrownewUnsupportedOperationException();
 }
 }

 publicvoidremoveELContextListener(ELContextListenerlistener){
 Applicationapp=getRIApplicationImpl();
 if(app!=null){
 app.removeELContextListener(listener);
 }else{
 thrownewUnsupportedOperationException();
 }

 }

 publicELContextListener[]getELContextListeners(){
 Applicationapp=getRIApplicationImpl();
 if(app!=null){
 //noinspectionTailRecursion
 returnapp.getELContextListeners();
 }else{
 thrownewUnsupportedOperationException();
 }
 }

publicabstractvoidaddValidator(StringvalidatorId,
 StringvalidatorClass);

publicabstractValidatorcreateValidator(StringvalidatorId)
 throwsFacesException;

publicabstractIterator<String>getValidatorIds();
publicabstractValueBindingcreateValueBinding(Stringref)
 throwsReferenceSyntaxException;


 //---------------------------------------------------------PrivateMethods


 privatestaticApplicationgetRIApplicationImpl(FacesContextcontext){
 ExternalContextextContext;
 if(context!=null){
 extContext=context.getExternalContext();
 }else{
 extContext=
 FacesContext.getCurrentInstance().getExternalContext();
 }
 if(extContext!=null){
 return((Application)extContext.getApplicationMap().
 get("com.sun.faces.ApplicationImpl"));
 }
 returnnull;
 }

 privatestaticApplicationgetRIApplicationImpl(){
 returngetRIApplicationImpl(null);
}