在Flex中访问JSP的session、application属性值

      在开发web程序的过程中，我们经常要从session、application等JSP内置对象中获取变量值，在jsp页面、servlet中我们很容易就能办到，但是在Flex中就比较麻烦。不过，通过变通的方法我们还是可以从session、application对象中获取变量值的，其思路就是：通过HttpService组件访问一个通用的HttpServlet类，在HttpServlet类中根据不同的条件从不同的JSP内置对象中获取变量值。

      下面给出主要的代码供参考：

 

一、HttpServlet类的源码：

public class JspServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        response.setContentType("text/html");

        String scope = request.getParameter("scope");
        String param = request.getParameter("param");
        String result = null;

        if(scope.equals("session")){
            result = (String)request.getSession().getAttribute(param);
        }else if(scope.equals("application")){
            result = (String)getServletContext().getAttribute(param);
        }

        PrintWriter out = response.getWriter();
        out.print(result);
        out.flush();
        out.close();
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        doGet(request, response);
    }
}

public class JspServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {

		response.setContentType("text/html");

		

		String scope = request.getParameter("scope");

		String param = request.getParameter("param");

		String result = null;

		

		if(scope.equals("session")){

			result = (String)request.getSession().getAttribute(param);

		}else if(scope.equals("application")){

			result = (String)getServletContext().getAttribute(param);

		}

		

		PrintWriter out = response.getWriter();

		out.print(result);

		out.flush();

		out.close();

	}



	public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {

		doGet(request, response);

	}

}

 

二、mxml文件的源码：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" initialize="init()">
    <mx:Script>
        <![CDATA[
            import mx.controls.Alert;
            import mx.rpc.Fault;
            import mx.rpc.events.FaultEvent;
            import mx.rpc.events.ResultEvent;

            private function call():void{
                jspServlet.request.scope = "application"; //表示要从application对象获取变量值
                jspServlet.request.param = "username"; //变量名
                jspServlet.send();
            }

            private function resultHandler(event:ResultEvent):void{
                txt1.text = event.result as String;
            }

            private function faultHandler(event:FaultEvent):void{
                var fault:Fault = event.fault;
                var s:String = (fault.faultDetail!=null) ? fault.faultDetail : fault.faultString;
                Alert.show(s);
            }

        ]]>
    </mx:Script>

    <mx:HTTPService id="jspServlet" url="../jspServlet"
        result="resultHandler(event)"
        fault="faultHandler(event)"
        resultFormat="text"
        method="POST"
        useProxy="false"
        showBusyCursor="true"/>

    <mx:Button x="27" y="28" label="Load" click="call()"/>
    <mx:TextArea x="27" y="58" width="450" height="143" id="txt1"/>

</mx:Application>