struts2 获得request session application的四种方式

（一）Map（在web.xml中必须使用2.1以上的配置）

public class LoginAction1 extends ActionSupport {

private Map request;

private Map session;

private Map application;

public LoginAction1() {

request = (Map)ActionContext.getContext().get("request");

session = ActionContext.getContext().getSession();

application = ActionContext.getContext().getApplication();

}

public String execute() {

request.put("r1", "r1");

session.put("s1", "s1");

application.put("a1", "a1");

return SUCCESS;

}

}

（二）继承并实现RequestAware,SessionAware, ApplicationAware 接口（依赖注入，强烈推荐使用）

public class LoginAction2 extends ActionSupport implements RequestAware,SessionAware, ApplicationAware {

private Map<String, Object> request;

private Map<String, Object> session;

private Map<String, Object> application;

//DI dependency injection

//IoC inverse of control

public String execute() {

request.put("r1", "r1");

session.put("s1", "s1");

application.put("a1", "a1");

return SUCCESS;

}

@Override

public void setRequest(Map<String, Object> request) {

this.request = request;

}

@Override

public void setSession(Map<String, Object> session) {

this.session = session;

}

@Override

public void setApplication(Map<String, Object> application) {

this.application = application;

}

}

（三）获得真实对象

public class LoginAction3 extends ActionSupport {

private HttpServletRequest request;

private HttpSession session;

private ServletContext application;

public LoginAction3() {

request = ServletActionContext.getRequest();

session = request.getSession();

application = session.getServletContext();

}

public String execute() {

request.setAttribute("r1", "r1");

session.setAttribute("s1", "s1");

application.setAttribute("a1", "a1");

return SUCCESS;

}

}

（四）依赖注入+获得真是对象

public class LoginAction4 extends ActionSupport implements ServletRequestAware {

private HttpServletRequest request;

private HttpSession session;

private ServletContext application;

public String execute() {

request.setAttribute("r1", "r1");

session.setAttribute("s1", "s1");

application.setAttribute("a1", "a1");

return SUCCESS;

}

@Override

public void setServletRequest(HttpServletRequest request) {

this.request = request;

this.session = request.getSession();

this.application = session.getServletContext();

}

}