ServletContextServletContext从他的package信息可以看出,它是标准的JavaEE WebApplication类库javax.servlet.ServletContextServletContext提供了标准的Servlet运行环境,其实就是一些servlet和web container进行通信的方法public interface ServletContext { // Returns the URL prefix for the ServletContext. public String getServletContextName(); //Returns the ServletContext for the uri. public ServletContext getContext(String uri); //Returns the context-path for the web-application. public String getContextPath(); //Returns the real file path for the given uri. public String getRealPath(String uri); public RequestDispatcher getRequestDispatcher(String uri); public RequestDispatcher getNamedDispatcher(String servletName);public Object getAttribute(String name);public Enumeration getAttributeNames();public void setAttribute(String name, Object value);public void removeAttribute(String name);注意:一个ServletContext对应一个命名空间的servlet( 比如/struts下的所有servlet),是被所有servlet共享的.There is one context per "web application" per Java Virtual Machine.(A "web application" is a collection of servlets and content installed under a specific subset of the server's URL namespace such as /catalog and possibly installed via a .war file.)ServletContext被包含在ServletConfig对象中,ServletConfig对象通常被servlet或filter的init()方法读取ServletConfig.getServletContext()filterconfig.getServletContext()ActionContext来源于Struts2 与 Struts1的本质不同.struts1时，由一个servlet (servlet org.apache.struts.action.ActionServlet)处理所有的*.dostruts2时，由一个filter(org.apache.struts2.dispatcher.FilterDispatcher)处理所有的请求struts1 仍旧属于servlet范畴,struts1 action 其本质仍是servlet.struts2 action 已经是普通的Java bean了,已经跳出了servlet 框架ActionContext就是为了弥补strtus2 action跳出标准servlet框架而造成的和WEB环境失去联系的缺陷ActionContext的主要作用:提供Web环境Context解决线程安全问题解决一些和其他框架或容器(siteMesh,webLogic)的兼容问题分析ActionContext源码 public class ActionContext implements Serializable { //ThreadLocal模式下的ActionContext实例,实现多线程下的线程安全/// static ThreadLocal actionContext = new ThreadLocal(); //Sets the action context for the current thread. public static void setContext(ActionContext context) { actionContext.set(context); } //Returns the ActionContext specific to the current thread. public static ActionContext getContext() { return (ActionContext) actionContext.get(); } ///定义放置"名/值对"的Map容器,这是ActionContext的主要功能/// Map context; // constractor // Creates a new ActionContext initialized with another context. public ActionContext(Map context) { this.context = context; } public void setContextMap(Map contextMap) { getContext().context = contextMap; } public Map getContextMap() { return context; }//Returns a value that is stored in the current ActionContext by doing a lookup using the value's key. public Object get(String key) { return context.get(key); } //Stores a value in the current ActionContext. The value can be looked up using the key. public void put(String key, Object value) { context.put(key, value); }///将各种功能属性放置入Map容器中/ //action name, Constant for the name of the action being executed. public static final String ACTION_NAME = "com.opensymphony.xwork2.ActionContext.name"; // ognl value stack public static final String VALUE_STACK = ValueStack.VALUE_STACK; public static final String SESSION = "com.opensymphony.xwork2.ActionContext.session"; public static final String APPLICATION = "com.opensymphony.xwork2.ActionContext.application"; public static final String PARAMETERS = "com.opensymphony.xwork2.ActionContext.parameters"; public static final String LOCALE = "com.opensymphony.xwork2.ActionContext.locale"; public static final String TYPE_CONVERTER = "com.opensymphony.xwork2.ActionContext.typeConverter"; public static final String ACTION_INVOCATION = "com.opensymphony.xwork2.ActionContext.actionInvocation"; public static final String CONVERSION_ERRORS = "com.opensymphony.xwork2.ActionContext.conversionErrors"; public static final String CONTAINER = "com.opensymphony.xwork2.ActionContext.container"; // 各种Action主属性:ActionName, ActionInvocation(调用action的相关信息), ognl value stack/// //Gets the name of the current Action. public String getName() { return (String) get(ACTION_NAME); } //Sets the name of the current Action in the ActionContext. public void setName(String name) { put(ACTION_NAME, name); } //Sets the action invocation (the execution state). public void setActionInvocation(ActionInvocation actionInvocation) { put(ACTION_INVOCATION, actionInvocation); } public ActionInvocation getActionInvocation() { return (ActionInvocation) get(ACTION_INVOCATION); } // Sets the OGNL value stack. public void setValueStack(ValueStack stack) { put(VALUE_STACK, stack); } //Gets the OGNL value stack. public ValueStack getValueStack() { return (ValueStack) get(VALUE_STACK); }各种 request请求包含的内容 //Returns a Map of the HttpServletRequest parameters public Map getParameters() { return (Map ) get(PARAMETERS); } public void setParameters(Map parameters) { put(PARAMETERS, parameters); } public void setSession(Map session) { put(SESSION, session); } public Map getSession() { return (Map ) get(SESSION); } public void setApplication(Map application) { put(APPLICATION, application); } public Map getApplication() { return (Map ) get(APPLICATION); } public void setConversionErrors(Map conversionErrors) { put(CONVERSION_ERRORS, conversionErrors); } public Map getConversionErrors() { Map errors = (Map) get(CONVERSION_ERRORS); if (errors == null) { errors = new HashMap (); setConversionErrors(errors); } return errors; } //Sets the Locale for the current action. public void setLocale(Locale locale) { put(LOCALE, locale); } public Locale getLocale() { Locale locale = (Locale) get(LOCALE); if (locale == null) { locale = Locale.getDefault(); setLocale(locale); } return locale; } public void setContainer(Container cont) { put(CONTAINER, cont); } public Container getContainer() { return (Container) get(CONTAINER); } public T getInstance(Class type) { Container cont = getContainer(); if (cont != null) { return cont.getInstance(type); } else { throw new XWorkException("Cannot find an initialized container for this request."); } } }ServletActionContext 其实是ActionContext的子类,其功能脱胎于ActionContext,对ActionContext的方法做了一定的包装,提供了更简便直观的方法 public class ServletActionContext extends ActionContext implements StrutsStatics {/Servlet Context 提供了多种操作ActionContext的静态方法,使获得Web对象更方便 //HTTP servlet request public static void setRequest(HttpServletRequest request) { ActionContext.getContext().put(HTTP_REQUEST, request); } public static HttpServletRequest getRequest() { return (HttpServletRequest) ActionContext.getContext().get(HTTP_REQUEST); } //HTTP servlet response public static void setResponse(HttpServletResponse response) { ActionContext.getContext().put(HTTP_RESPONSE, response); } public static HttpServletResponse getResponse() { return (HttpServletResponse) ActionContext.getContext().get(HTTP_RESPONSE); } //servlet context. public static ServletContext getServletContext() { return (ServletContext) ActionContext.getContext().get(SERVLET_CONTEXT); } public static void setServletContext(ServletContext servletContext) { ActionContext.getContext().put(SERVLET_CONTEXT, servletContext); } posted on 2016-12-19 22:42 阅读( ...) 评论( ...)