通过ActionContext类访问Servlet对象
?ActionContext类位于com.opensymphony.xwork2中，提供一系列相关方法用于访问保存在ServletContext、HttpSession、HttpServletRequest中的信息，并且存储在Map中。需要注意的是，该类并没有提供获取ServletContext、HttpSession、HttpServletRequest等对象的方法。ActionContext类的常用方法见下表：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head>??? <title>My JSP 'session.jsp' starting page</title></head><body>??? ${id }<br>??? ${name }</body></html>??? 请求参数通过表单页面idname.jsp提供。代码清单34：idname.jsp<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head>??? <title>My JSP 'idname.jsp' starting page</title></head><body>??? <form action="servletAction.action" method="post">??? ??? ID:<input name="id"><br>??? ??? Name:<input name="name"><br>??? ??? <input type="submit" value="提交">??? </form></body></html>??? 通过http://localhost:8081/Struts2Demo/idname.jsp地址访问即可，图24是表单输入效果，图25是表单提交后将请求发送给Action，最后显示在session.jsp中的效果：
??? （图24）
??? （图25）??? ActionContext类是xwork提供的，struts2定义了一个新类org.apache.struts2. ServletActionContext，该类继承自ActionContext：代码清单35：ServletActionContext.java的定义public class ServletActionContext extends ActionContext implements StrutsStatics {}??? ServletActionContext类和ActionContext相比扩展了更多的方法，主要是一些静态方法，该类的源代码如下：代码清单36：ServletActionContext.java的完整定义public class ServletActionContext extends ActionContext implements StrutsStatics {??? private static final long serialVersionUID = -666854718275106687L;??? public static final String STRUTS_VALUESTACK_KEY = "struts.valueStack";??? public static final String ACTION_MAPPING = "struts.actionMapping";??? @SuppressWarnings("unused")??? private ServletActionContext(Map context) {??????? super(context);??? }??? public static ActionContext getActionContext(HttpServletRequest req) {??????? ValueStack vs = getValueStack(req);??????? if (vs != null) {??????????? return new ActionContext(vs.getContext());??????? } else {??????????? return null;??????? }??? }??? public static ValueStack getValueStack(HttpServletRequest req) {??????? return (ValueStack) req.getAttribute(STRUTS_VALUESTACK_KEY);??? }??? public static ActionMapping getActionMapping() {??????? return (ActionMapping) ActionContext.getContext().get(ACTION_MAPPING);??? }??? public static PageContext getPageContext() {??????? return (PageContext) ActionContext.getContext().get(PAGE_CONTEXT);??? }??? public static void setRequest(HttpServletRequest request) {??????? ActionContext.getContext().put(HTTP_REQUEST, request);??? }??? public static HttpServletRequest getRequest() {??????? return (HttpServletRequest) ActionContext.getContext().get(HTTP_REQUEST);??? }??? public static void setResponse(HttpServletResponse response) {??????? ActionContext.getContext().put(HTTP_RESPONSE, response);??? }??? public static HttpServletResponse getResponse() {?? ?????return (HttpServletResponse) ActionContext.getContext().get(HTTP_RESPONSE);??? }??? public static ServletContext getServletContext() {??????? return (ServletContext) ActionContext.getContext().get(SERVLET_CONTEXT);??? }??? public static void setServletContext(ServletContext servletContext) {??????? ActionContext.getContext().put(SERVLET_CONTEXT, servletContext);??? }}??? 注意粗体部分，getPageContext()方法返回PageContext的引用，getRequest()方法返回HttpServletRequest的引用，getResponse()方法返回HttpServletResponse的引用，getServletContext()方法返回ServletContext的引用。我们将代码清单31修改成代码清单37所示：代码清单37：ServletAction.java的修改版public class ServletAction {??? public String execute(){?????? String id = ServletActionContext.getRequest().getParameter("id");?????? String name = ServletActionContext.getRequest().getParameter("name");???????????? Map sessionMap = ServletActionContext.getContext().getSession();?????? sessionMap.put("id", id);?????? sessionMap.put("name", name);???????????? System.out.println("id=" + sessionMap.get("id"));?????? System.out.println("name=" + sessionMap.get("name"));?????? return "toSession";??? }}3.3.2 通过IOC访问Servlet对象??? 在Struts2中，可以通过IOC（依赖注入）将Servlet对象注入到Action中，这一切都是由一组接口决定的，这一组接口有一个共同点，名称都由Aware结尾。以下是这些接口的解释说明：?????? <result name="toSession">/session.jsp</result></action>??? 可以看出，不需要做其他额外的配置。
转http://hi.baidu.com/%C6%C6%D4%C6%B5%B6/blog/item/93be0c2240178cf6d6cae26f.html