转自：http://chen106106.iteye.com/blog/1318596

1.在javax.servlet.Filter中直接获取

ServletContext context = config.getServletContext();

2.在HttpServlet中直接获取

this.getServletContext()

3.在其他方法中，通过HttpRequest获得

request.getSession().getServletContext();

当然struts2中还有常见的两种方法获得:

　　获取HttpServletRequest / HttpSession / ServletContext / HttpServletResponse对象

方法一，通过ServletActionContext.类直接获取：

public String rsa() throws Exception{　　HttpServletRequest request = ServletActionContext.getRequest();　　ServletContext servletContext = ServletActionContext.getServletContext();　　request.getSession()　　HttpServletResponse response = ServletActionContext.getResponse();　　return "scope";}

方法二，实现指定接口，由struts框架运行时注入：

public class HelloWorldAction implements ServletRequestAware, ServletResponseAware, ServletContextAware{　　private HttpServletRequest request;　　private ServletContext servletContext;　　private HttpServletResponse response;　　public void setServletRequest(HttpServletRequest req) {　　　　this.request=req;　　}　　public void setServletResponse(HttpServletResponse res) {　　　　this.response=res;　　}　　public void setServletContext(ServletContext ser) {　　　　this.servletContext=ser;　　}}