由于iframe导致的问题

我在一个jsp表单中有两个单选按钮（遍历和直接）。traverse用于正常提交表单，direct用于使用iframe汇总表单。使用iframe提交表单后，如果我尝试正常提交，则应用程序将在新窗口中打开。如何防止表单在新窗口中打开。

function submitAction() {       
        var fileValue = document.getElementById("file1").value;     
        if (fileValue == "") {
            alert("Please uploaded file type of .war or .html type");
            return false;
        }           
        var valuePassed = getCheckedRadio();
        var url="uploadfile.do?rad=" + valuePassed;     
        if (valuePassed == "traverse") {                    
            document.EntryForm.action = url; 
            document.EntryForm.submit();    //Normal way of submitting.                         
        }else if (valuePassed == "direct") {
            alert("direct");    
            url=url+"&fileName="+fileValue;             
            directConvert(document.EntryForm,url,'downloaddiv');                }
    }

function directConvert(form, action_url, div_id){               
        // Create the iframe...
        var iframe = document.createElement("iframe");
        iframe.setAttribute("id", "upload_iframe");     
        iframe.setAttribute("name", "upload_iframe");
        iframe.setAttribute("width", "0");
        iframe.setAttribute("height", "0");
        iframe.setAttribute("border", "0");
        iframe.setAttribute("style", "width: 0; height: 0; border: none;");
        // Add to document...
        form.parentNode.appendChild(iframe);
        //window.frames['upload_iframe'].name = "upload_iframe";     
        iframeId = document.getElementById("upload_iframe");     
        // Add event...
        var eventHandler = function () {     
                if (iframeId.detachEvent) iframeId.detachEvent("onload", eventHandler);
                else iframeId.removeEventListener("load", eventHandler, false);             
                // Message from server...    
                if (iframeId.contentDocument) {                
                    content = iframeId.contentDocument.body.innerHTML;
                } else if (iframeId.contentWindow) {                    
                    content = iframeId.contentWindow.document.body.innerHTML;
                } else if (iframeId.document) {                 
                    content = iframeId.document.body.innerHTML;
                }               
                document.getElementById(div_id).innerHTML = content;     
                // Del the iframe...
                setTimeout('iframeId.parentNode.removeChild(iframeId)',50);
            }
        if (iframeId.addEventListener) iframeId.addEventListener("load", eventHandler, true);
        if (iframeId.attachEvent) iframeId.attachEvent("onload", eventHandler);  
        // Set properties of form...
        form.setAttribute("target", "upload_iframe");
        form.setAttribute("action", action_url);
        form.setAttribute("method", "post");
        form.setAttribute("enctype", "multipart/form-data");
        form.setAttribute("encoding", "multipart/form-data");  
        form.submit();              
    }

当我第一次尝试遍历时，它工作正常，但在通过iframe提交后，如果我尝试遍历，它将在新窗口中打开。如何防止它在新窗口中打开。