struts2获取session与request对象

小鱼儿 2022-09-28 01:23 156阅读 0赞

非IoC方式

要获得上述对象，关键Struts 2.0中com.opensymphony.xwork2.ActionContext类。我们可以通过它的静态方法getContext()获取当前 Action的上下文对象。 另外，org.apache.struts2.ServletActionContext作为辅助类（Helper Class），可以帮助您快捷地获得这几个对象。

HttpServletRequest request = ServletActionContext.getRequest();  
HttpServletResponse response = ServletActionContext.getResponse();  
HttpSession session = request.getSession();

如果你只是想访问session的属性（Attribute），你也可以通过ActionContext.getContext().getSession()获取或添加session范围（Scoped）的对象。

IoC方式

要使用IoC方式，我们首先要告诉IoC容器（Container）想取得某个对象的意愿，通过实现相应的接口做到这点。具体实现，请参考例6 IocServlet.java。

*例6 classes/tutorial/NonIoCServlet.java*  
package tutorial;

import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import javax.servlet.http.HttpSession;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionContext;  
import com.opensymphony.xwork2.ActionSupport;

publicclass NonIoCServlet extends ActionSupport \{  
    private String message;  
     
    public String getMessage() \{  
        return message;         
    \}  
     
    @Override  
    public String execute() \{     
        ActionContext.getContext().getSession().put("msg", "Hello World from Session!");  
         
        HttpServletRequest request = ServletActionContext.getRequest();  
        HttpServletResponse response = ServletActionContext.getResponse();         
        HttpSession session = request.getSession();  
         
        StringBuffer sb =new StringBuffer("Message from request: ");  
        sb.append(request.getParameter("msg"));  
        sb.append("<br>Response Buffer Size: ");  
        sb.append(response.getBufferSize());  
        sb.append("<br>Session ID: ");  
        sb.append(session.getId());  
         
        message = sb.toString();  
        return SUCCESS;  
    \}  
\}

*例6 classes/tutorial/IoCServlet.java*  
package tutorial;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import javax.servlet.http.HttpSession;

import org.apache.struts2.interceptor.ServletRequestAware;  
import org.apache.struts2.interceptor.ServletResponseAware;  
import org.apache.struts2.interceptor.SessionAware;

import com.opensymphony.xwork2.ActionContext;  
import com.opensymphony.xwork2.ActionSupport;

publicclass IoCServlet extends ActionSupport implements SessionAware, ServletRequestAware, ServletResponseAware \{  
    private String message;  
    private Map att;  
    private HttpServletRequest request;  
    private HttpServletResponse response;     
     
    public String getMessage() \{  
        return message;         
    \}  
     
    publicvoid setSession(Map att) \{  
        this.att = att;  
    \}  
     
    publicvoid setServletRequest(HttpServletRequest request) \{  
        this.request = request;  
    \}  
     
    publicvoid setServletResponse(HttpServletResponse response) \{  
        this.response = response;  
    \}  
     
    @Override  
    public String execute() \{         
        att.put("msg", "Hello World from Session!");  
         
        HttpSession session = request.getSession();  
         
        StringBuffer sb =new StringBuffer("Message from request: ");  
        sb.append(request.getParameter("msg"));  
        sb.append("<br>Response Buffer Size: ");  
        sb.append(response.getBufferSize());  
        sb.append("<br>Session ID: ");  
        sb.append(session.getId());  
         
        message = sb.toString();  
        return SUCCESS;  
    \}  
\}

*例6 Servlet.jsp*  
<%@ page contentType="text/html; charset=UTF-8" %>  
<%@ taglib prefix="s" uri="/struts-tags"%>  
<html>  
<head>  
    <title>Hello World!</title>  
</head>  
<body>  
    <h2>  
        <s:property value="message" escape="false"/>  
        <br>Message from session: <s:property value="\#session.msg"/>  
    </h2>  
</body>  
</html>

*例6 classes/struts.xml中NonIocServlet和IoCServlet Action的配置*  
<action name="NonIoCServlet" class="tutorial.NonIoCServlet">  
<result>/Servlet.jsp</result>  
</action>  
<action name="IoCServlet" class="tutorial.IoCServlet">  
<result>/Servlet.jsp</result>  
</action>

运行Tomcat，在浏览器地址栏中键入[http://localhost:8080/Struts2\_Action/NonIoCServlet.action?msg=Hello%20World][http_localhost_8080_Struts2_Action_NonIoCServlet.action_msg_Hello_20World]! 或[http://localhost:8080/Struts2\_Action/IoCServlet.action?msg=Hello%20World][http_localhost_8080_Struts2_Action_IoCServlet.action_msg_Hello_20World]!，出现如图7所示页面。

![图7 Servlet.jsp的输出页面][7 Servlet.jsp]

在Servlet.jsp中，我用了两次property标志，第一次将escape设为false为了在JSP中输出<br>转行，第二次的value中的OGNL为“\#session.msg”，它的作用与session.getAttribute("msg")等同。

[http_localhost_8080_Struts2_Action_NonIoCServlet.action_msg_Hello_20World]: http://localhost:8080/Struts2_Act%3Cwbr%3Eion/NonIoCServlet.act%3Cwbr%3Eion?msg=Hello%20World
[http_localhost_8080_Struts2_Action_IoCServlet.action_msg_Hello_20World]: http://localhost:8080/Struts2_Act%3Cwbr%3Eion/IoCServlet.act%3Cwbr%3Eion?msg=Hello%20World
[7 Servlet.jsp]: /images/20220708/a256f7a2314a455097311ee0f0b2afa0.png