strtus2上传文件的问题

前台代码<form action="addSchedul"  enctype="multipart/form-data" method="post" id="orderfrm">
<input id="compLog" class="InputFile" type="file" size="40" name="compLog">
</form>
后台代码
private File compLog;
    private String comLogFileName;
    private String comLogContentType;
InputStream in;
                OutputStream out;
                try {
                    in=new BufferedInputStream(new FileInputStream(compLog));
                    String root= ServletActionContext.getServletContext().getRealPath("/company/comlog");
                    long time = System.currentTimeMillis();
                    
                    String tfileName=root+time+comLogContentType;
                    out =new BufferedOutputStream(new FileOutputStream(tfileName));
                    byte[] buffer = new byte[4096];
                    int lenght=0;
                    while((lenght=in.read(buffer))>0)
                    {
                        out.write(buffer,0,lenght);
                    }
                    if ( null != in)  {in.close(); } 
                    if ( null != out)  {out.close();}
                    comSceneSchedul.setCompImage(comLogFileName);
                    errMsg="上传成功";
                    System.out.println(tfileName);
                } catch (Exception e) {
                    // TODO: handle exception
                    errMsg="上传失败";
                    e.printStackTrace();
                }
东西已经可以上传了，可是为什么comLogFileName和comLogContentType这两个值一直为Nullstrtus2 jsp