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);
}