JSF 源代码赏析之Lifecycle

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JSF SUN

   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：

// Relationship Instance Variables
private ResponseStream responseStream = null;
private ResponseWriter responseWriter = null;
private ExternalContext externalContext = null;
private Application application = null;
private UIViewRoot viewRoot = null;
private ELContext elContext = null;
private RenderKitFactory rkFactory;
private RenderKit lastRk;
private String lastRkId;
/**
* Store mapping of clientId to ArrayList of FacesMessage
* instances. The null key is used to represent FacesMessage instances
* that are not associated with a clientId instance.
*/
private Map<String,List<FacesMessage>> componentMessageLists;
// Attribute Instance Variables
private boolean renderResponse = false;
private boolean responseComplete = 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:

public abstract class ExternalContext {
public static final String BASIC_AUTH = "BASIC";
public static final String CLIENT_CERT_AUTH = "CLIENT_CERT";
public static final String DIGEST_AUTH = "DIGEST";
public static final String FORM_AUTH = "FORM";
// ---------------------------------------------------------- Public Methods
public abstract void dispatch(String path)
throws IOException;
public abstract String encodeActionURL(String url);
public abstract String encodeNamespace(String name);
public abstract String encodeResourceURL(String url);
public abstract String getAuthType();
public abstract Object getContext();
public abstract String getInitParameter(String name);
public abstract Map getInitParameterMap();
public abstract String getRemoteUser();
public abstract Object getRequest();
public void setRequest(Object request) {
ExternalContext impl;
if (null != (impl = (ExternalContext) this.getRequestMap().
get("com.sun.faces.ExternalContextImpl"))) {
impl.setRequest(request);
return;
}
throw new UnsupportedOperationException();
}
public void setRequestCharacterEncoding(String encoding) throws UnsupportedEncodingException {
ExternalContext impl;
if (null != (impl = (ExternalContext) this.getRequestMap().
get("com.sun.faces.ExternalContextImpl"))) {
impl.setRequestCharacterEncoding(encoding);
return;
}
throw new UnsupportedOperationException();
}
public abstract String getRequestContextPath();
public abstract Locale getRequestLocale();
public abstract Iterator<locale></locale> getRequestLocales();
public abstract Iterator<string></string> getRequestParameterNames();
public abstract String getRequestPathInfo();
public abstract String getRequestServletPath();
public String getRequestCharacterEncoding() {
ExternalContext impl;
if (null != (impl = (ExternalContext) this.getRequestMap().
get("com.sun.faces.ExternalContextImpl"))) {
//noinspection TailRecursion
return impl.getRequestCharacterEncoding();
}
throw new UnsupportedOperationException();
}
public String getRequestContentType() {
ExternalContext impl;
if (null != (impl = (ExternalContext) this.getRequestMap().
get("com.sun.faces.ExternalContextImpl"))) {
//noinspection TailRecursion
return impl.getRequestContentType();
}
throw new UnsupportedOperationException();
}
public String getResponseCharacterEncoding() {
ExternalContext impl;
if (null != (impl = (ExternalContext) this.getRequestMap().
get("com.sun.faces.ExternalContextImpl"))) {
//noinspection TailRecursion
return impl.getResponseCharacterEncoding();
}
throw new UnsupportedOperationException();
}
public String getResponseContentType() {
ExternalContext impl;
if (null != (impl = (ExternalContext) this.getRequestMap().
get("com.sun.faces.ExternalContextImpl"))) {
//noinspection TailRecursion
return impl.getResponseContentType();
}
throw new UnsupportedOperationException();
}
public abstract URL getResource(String path) throws MalformedURLException;
public abstract InputStream getResourceAsStream(String path);
public abstract Set<string></string> getResourcePaths(String path);
public abstract Object getResponse();
public abstract Object getSession(boolean create);
public abstract Principal getUserPrincipal();
public abstract boolean isUserInRole(String role);
public abstract void log(String message, Throwable exception);
public abstract void redirect(String url) throws IOException;
}

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
public abstract ActionListener getActionListener();
public abstract void setActionListener(ActionListener listener);
public abstract void setDefaultLocale(Locale locale);
public abstract String getDefaultRenderKitId();
public abstract void setDefaultRenderKitId(String renderKitId);
public abstract String getMessageBundle();
public abstract void setMessageBundle(String bundle);
public abstract NavigationHandler getNavigationHandler();
public abstract void setNavigationHandler(NavigationHandler handler);
public abstract PropertyResolver getPropertyResolver();
public ResourceBundle getResourceBundle(FacesContext ctx, String name) {
Application app = getRIApplicationImpl(ctx);
if (app != null) {
//noinspection TailRecursion
return app.getResourceBundle(ctx, name);
}
throw new UnsupportedOperationException();
}
public abstract VariableResolver getVariableResolver();
public abstract void setVariableResolver(VariableResolver resolver);
public void addELResolver(ELResolver resolver) {
Application app = getRIApplicationImpl();
if (app != null) {
app.addELResolver(resolver);
} else {
throw new UnsupportedOperationException();
}
}
public ELResolver getELResolver() {
Application app = getRIApplicationImpl();
if (app != null) {
//noinspection TailRecursion
return app.getELResolver();
}
throw new UnsupportedOperationException();
}
public abstract ViewHandler getViewHandler();
public abstract void setViewHandler(ViewHandler handler);
public abstract StateManager getStateManager();
public abstract void setStateManager(StateManager manager);
// ------------------------------------------------------- Object Factories
public abstract void addComponent(String componentType,
String componentClass);
public abstract UIComponent createComponent(String componentType)
throws FacesException;
public abstract UIComponent createComponent(ValueBinding componentBinding,
FacesContext context,
String componentType)
rows FacesException;
public UIComponent createComponent(ValueExpression componentExpression,
FacesContext context,
String componentType)
rows FacesException {
if (null == componentExpression || null == context ||
null == componentType) {
// PENDING - i18n
StringBuilder builder = new StringBuilder(64);
builder.append("null parameters - ");
builder.append("componentExpression: ").append(componentExpression);
builder.append(", context: ").append(context);
builder.append(", componentType: ").append(componentType);
throw new NullPointerException(builder.toString());
}
Object result;
boolean createOne = false;
try {
if (null != (result =
componentExpression.getValue(context.getELContext()))) {
// if the result is not an instance of UIComponent
createOne = (!(result instanceof UIComponent));
// we have to create one.
}
if (null == result || createOne) {
result = this.createComponent(componentType);
componentExpression.setValue((context.getELContext()), result);
}
} catch (ELException elex) {
throw new FacesException(elex);
}
return (UIComponent) result;
}
public abstract Iterator<String> getComponentTypes();
public abstract void addConverter(String converterId,
public abstract void addConverter(Class targetClass,
String converterClass);
public abstract Converter createConverter(String converterId);
public abstract Converter createConverter(Class targetClass);
public abstract Iterator<String> getConverterIds();
public ExpressionFactory getExpressionFactory() {
Application app = getRIApplicationImpl();
if (app != null) {
//noinspection TailRecursion
return app.getExpressionFactory();
}
throw new UnsupportedOperationException();
}
public Object evaluateExpressionGet(FacesContext context,
String expression,
Class expectedType) throws ELException {
Application app = getRIApplicationImpl(context);
if (app != null) {
//noinspection TailRecursion
return app.evaluateExpressionGet(context, expression, expectedType);
}
throw new UnsupportedOperationException();
}
public abstract MethodBinding createMethodBinding(String ref,
Class params[])
throws ReferenceSyntaxException;
public abstract Iterator<Locale> getSupportedLocales();
public abstract void setSupportedLocales(Collection<Locale> locales);
public void addELContextListener(ELContextListener listener) {
Application app = getRIApplicationImpl();
if (app != null) {
app.addELContextListener(listener);
} else {
throw new UnsupportedOperationException();
}
}
public void removeELContextListener(ELContextListener listener) {
Application app = getRIApplicationImpl();
if (app != null) {
app.removeELContextListener(listener);
} else {
throw new UnsupportedOperationException();
}
}
public ELContextListener [] getELContextListeners() {
Application app = getRIApplicationImpl();
if (app != null) {
//noinspection TailRecursion
return app.getELContextListeners();
} else {
throw new UnsupportedOperationException();
}
}
public abstract void addValidator(String validatorId,
String validatorClass);
public abstract Validator createValidator(String validatorId)
throws FacesException;
public abstract Iterator<String> getValidatorIds();
public abstract ValueBinding createValueBinding(String ref)
throws ReferenceSyntaxException;
// --------------------------------------------------------- Private Methods
private static Application getRIApplicationImpl(FacesContext context) {
ExternalContext extContext;
if (context != null) {
extContext = context.getExternalContext();
} else {
extContext =
FacesContext.getCurrentInstance().getExternalContext();
}
if (extContext != null) {
return ((Application) extContext.getApplicationMap().
get("com.sun.faces.ApplicationImpl"));
}
return null;
}
private static Application getRIApplicationImpl() {
return getRIApplicationImpl(null);
}

未完待续。

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源码讲解renderResponse和responseComplete ... | 在JSF中取得当前行序号的方法

2007-11-15 23:41
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评论(3)
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3 楼 wst0350 2011-09-05

2 楼 haiyupeter 2009-05-13

首先我觉得你的写的对这些源码的分析还是不错的..希望以后再多写一些出来..

不过在本文中你不多讲一下生命周期里每一阶段主要是做什么的吗?
待续了那么久了..
比如第一阶段:恢复视图
第二阶段:应用请求值
第三阶段:验证请救值
第四阶段:绑定模型域
第五阶段:调用应用程序
第六阶段:渲染

然后每一阶段都挺重要的..

1 楼 chen.fa 2007-12-13

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