使用struts2实现文件下载

<action name="downloadAction" class="">
<result type="stream">
<param name="contentDispositon">attachment;filename=${filename}</param><!--attachment表示不打开下载，设置文件的名字-->
<param name="inputName">downloadFile</param><!-- 设置读取的方法(在action中的方法对应的getDownloadFile(){}) -->
</result>
</action>

public InputStream getDownloadFile(){
        try{
            if(1==number){
                this.filename=new String(this.filename.getBytes("gbk"),"8859_1");
                return ServletActionContext.getServletContext().getResourceAsStream("/upload/java.txt");
            }else{
                return ServletActionContext.getServletContext().getResourceAsStream("/upload/....");
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }
        
        return null;        
    }