隐藏文件域，通过变相的方式提交文件。

<script type="text/javascript">
Object.reEvent = function () {
 //获取Event
 return window.event ? window.event : (function (o) {
  do {
   o = o.caller;
  } while (o && !/^\[object[ A-Za-z]*Event\]$/.test(o.arguments[0]));
  return o.arguments[0];
 })(this.reEvent);
};

var $P = {

 reMouse : function () {
 //获取鼠标绝对位置
  var e = Object.reEvent();
  return {
   x : (document.documentElement.scrollLeft || document.body.scrollLeft) + e.clientX,
   y : (document.documentElement.scrollTop || document.body.scrollTop) + e.clientY
  };
 }
};

function submit() {
 document.form1.submit();
}

var show = function () {

 var mos = $P.reMouse(), wc = document.getElementById("wc");
 
 with (wc.style) {
  left = mos.x - 200 + "px";
  top = mos.y - 10 + "px";
 }
};
</script>
先添加一个附件,然后提交,这时提示拒绝访问错误!
<form id="form1">
 
 <div>
 <input type="file" name="file" id="wc" style="top:0px;height:20px;position:absolute;opacity:0;filter:alpha(opacity=50);" onchange="abc.click();">
 </div>
 <input type="button" value="增加" onmousemove="show()">
 <input type="button" value="提交" id="abc" onclick="submit()">
</form>

 

我改写后JS的代码，只是参照，要根据需求来做的。。
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<script type="text/javascript">
var fileObject = {
    move: function(fileId) {
        var posX = (document.documentElement.scrollLeft || document.body.scrollLeft) + event.clientX;
        var posY = (document.documentElement.scrollTop || document.body.scrollTop) + event.clientY;
        with (document.getElementById(fileId).style) {
            left = posX - 200 + "px";
            top = posY - 10 + "px";
        }
    },
    click: function(tableId, raiseEventId) {
        var raiseEventObject = document.getElementById(raiseEventId);
        var table = document.getElementById(tableId);
        var rows = table.rows;
        var currentRow = null;
        for (var i = 0; i < rows.length; i++) {
            var inputs = rows[i].cells[0].all.tags("INPUT");
            if (inputs != null) {
                for (var j = 0; j < inputs.length; j++) {
                    if (inputs[j].type == "checkbox") {
                        if (inputs[j].checked) currentRow = rows[i];
                        break;
                    }
                }
            }
            if (currentRow != null) break;
        }
        if (currentRow == null) {
            raiseEventObject.click();
            return false;
        } else {
            var inputs = currentRow.cells[currentRow.cells.length - 1].all.tags("INPUT");
            if (inputs.length > 0) {
                return confirm("File already exist, are you sure?");
            }
            return true;
        }       
    },
    change: function(raiseEventId) {
        var raiseEventObject = document.getElementById(raiseEventId);
        if (raiseEventObject != null && raiseEventObject.click()) {
            raiseEventObject.click();
        }
    }
};
</script>