webwork对象的引用

问题描述：

       webwork的视图显示时，可以.jsp文件中直接使用格式<%  String ret = (String)request.getAttribute("test1"); %>获取request中的对象数值，如果test1在request请求中不存在，它的值应是多少呢？

 

问题验证：

       第一步：创建test.java文件，主要是通过request设置对象的值。

内容：

import com.opensymphony.webwork.ServletActionContext;
import com.opensymphony.xwork.Action;
import java.util.*;
import javax.servlet.http.HttpServletRequest;
import java.math.BigDecimal;
import com.opensymphony.webwork.ServletActionContext;
import org.apache.commons.io.FileUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.util.Map;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.opensymphony.xwork.ActionContext;

public class HelloWorldAction implements Action
{
    protected HttpServletResponse response;
    protected HttpServletRequest request;
    protected Map session;
    private static final long serialVersionUID = 7228637992665838810L; 
    private static String chmod = "chmod 775 ";
    private static Log LOG = LogFactory.getLog(HelloWorldAction.class);
    public String execute()
        throws Exception
    {
        return SUCCESS;
    }
     
    public String  test()
    {     
     try{
           ActionContext ctx = ActionContext.getContext();
           request = (HttpServletRequest)ctx.get(ServletActionContext.HTTP_REQUEST);
           String s = request.getParameter("test");
           request.setAttribute("test", "1");
     }catch (Exception e) {
           LOG.error(e);
     }
     return SUCCESS;
    }
 public void setServletRequest(HttpServletRequest request) {
  this.request = request;
 }

 public void setServletResponse(HttpServletResponse response) {
  this.response = response;
 }

 public void setSession(Map session) {
  this.session = session;
 }

 public HttpServletRequest getRequest() {
  return request;
 }

 public void setRequest(HttpServletRequest request) {
  this.request = request;
 }

 public HttpServletResponse getResponse() {
  return response;
 }

 public void setResponse(HttpServletResponse response) {
  this.response = response;
 }
 public Map getSession() {
  return session;
 }
}

       第二步：创建test.ftl文件（点击next按钮跳转至test1.jsp，这样才能有request请求），test1.jsp文件，主要是获取对象的值。

test.jsp内容：

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<%
    //String ret = (String)request.getAttribute("test1"); the object doesn't exist  and return null

      String ret = (String)request.getAttribute("test");  //the object exist and return 1;

%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>my test</title>
</head>
<body>
<table><tr><td><%=ret%></td></tr><table>
</body>
</html>

       第三步：创建修改xwork.xml。

内容：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xwork PUBLIC
 "-//OpenSymphony Group//XWork 1.1.1//EN"
 "http://www.opensymphony.com/xwork/xwork-1.1.1.dtd">
<xwork>
 <include file="webwork-default.xml"/>
 <package name="default" extends="webwork-default">
  <action name="hello" class="HelloWorldAction" method="test">
   <result name="success" type="dispatcher">
         <param name="location">test1.jsp</param>
   </result>
  </action>
 </package>
</xwork>

结果：

   >1. 如果对象在request中存在，则显示值 1

   >2. 如果对象在request中不存在，则显示值 null

问题结论：