1 通过接口进行对象注入，action必须是实现相应的接口，struts就可以将指定的对象传递给action类 ServletContextAware接口：可以获得ServletContext对象 ServletResponseAware接口：可以获得ServletResponse对象 ServletRequestAware接口：可以获得ServletRequest对象 request.getSession获得session对象
public class ServletAction extends ActionSupport implements ServletRequestAware{ private HttpServletRequest request; @Override public void setServletRequest(HttpServletRequest request) { this.request = request; } @Override public String execute() throws Exception { System.out.println(request.getContextPath()); return SUCCESS; } }执行结果：
2 ServletActionContext 工具类，struts 的action类中获得servlet的api 获得servlet 对象，可以操作域数据，可以调用其他api HttpServletRequest ServletActionContext.getRequest(); HttpSession ServletActionContext.getRequest().getSession(); ServletContext ServletActionContext.getServletContext();
public class ServletAction extends ActionSupport { @Override public String execute() throws Exception { ServletActionContext.getResponse(); ServletActionContext.getRequest().setAttribute("sac", "ServletActionContext_request"); ServletActionContext.getRequest().getSession().setAttribute("sac", "ServletActionContext_session"); ServletActionContext.getServletContext().setAttribute("sac", "ServletActionContext_application"); return SUCCESS; } }jsp代码：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <body> <h3>获得3作用域内容 -- ServletActionContext</h3> ${requestScope.sac} <br/> ${sessionScope.sac} <br/> ${applicationScope.sac} <br/> </body> </html>执行结果：
3 通过Action上下文对象ActionContext，可以间接对servlet 域数据进行操作，实现了解耦，不依赖于servlet api 获得ActionContext实例：ActionContext.getContext() 间接操作域数据
public class ServletAction extends ActionSupport { @Override public String execute() throws Exception { ActionContext.getContext().put("ac", "ActionContext_request"); ActionContext.getContext().getSession().put("ac", "ActionContext_session"); ActionContext.getContext().getApplication().put("ac", "ActionContext_application"); return SUCCESS; } }jsp代码：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <body> <h3>获得3作用域内容-- ActionContext</h3> ${requestScope.ac} <br/> ${sessionScope.ac} <br/> ${applicationScope.ac} <br/> </body> </html>执行结果：
