1.在javax.servlet.Filter中直接獲取

ServletContext context = config.getServletContext();

2.在HttpServlet中直接獲取

this.getServletContext()

3.在其他方法中，通過HttpRequest獲得

request.getSession().getServletContext();



當然struts2中還有常見的兩種方法獲得
獲取HttpServletRequest / HttpSession / ServletContext / HttpServletResponse物件

方法一，通過ServletActionContext.類直接獲取：
public String rsa() throws Exception{
HttpServletRequest request = ServletActionContext.getRequest();
ServletContext servletContext = ServletActionContext.getServletContext();
request.getSession()
HttpServletResponse response = ServletActionContext.getResponse();
return "scope";
}
方法二，實現指定介面，由struts框架執行時注入：
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;
}
}