Question

SSM框架的form表单提交

//这是form表单里的input file，用c标签做了一些限制，但是为什么不传文件（就是不选文件）到后台，后台显示文件长度为1？
<div class="weui-uploader__input-box" id="test2">
<c:if test="${not empty contract}">
<c:if test="${not empty contract.atta}">
<input id="attaPath" name="attaPath" hidden="hidden" type="text" value="${contract.atta}"/>
<input id="atta" name="atta" class="weui-uploader__input" type="file" multiple>
</c:if>
<c:if test="${empty contract.atta}">
<input id="attaPath" hidden="hidden" type="text" value=""/>
<input id="atta" name="atta" class="weui-uploader__input" type="file" multiple>
</c:if>
</c:if>
<c:if test="${empty contract}">
<input id="atta" name="atta" class="weui-uploader__input" type="file" multiple>
</c:if>
</div>

//用以下js清空div里面内容可以后台得到文件长度为0
function reset(){
$("#test2").html("");
itemHtml = '<input id="attaPath" hidden="hidden" type="text" value=""/><input id="atta" class="weui-uploader__input" type="file" multiple />';
$("#test2").append(itemHtml);
$("#attrfile").html("");
//需要重新加载js文件，要不然ul那里没显示
var tmpl2 = '<li class="weui-uploader__file" ><a href="#">#url#</a></li>';
$atta = $("#atta");
$attrfile = $("#attrfile");
$atta.on("change", function(e){
var src, url = window.URL || window.webkitURL || window.mozURL, files = e.target.files;
var attafiles = document.getElementById('atta').files;
for (var i = 0, len = files.length; i < len; ++i) {
var file = files[i];
var attafile = attafiles[i];
formData.append("attafile["+(formData.attalength+1)+"]", attafile);
if (url) {
src = url.createObjectURL(file);
} else {
src = e.target.result;
}
formData.attalength = formData.attalength+1;
$attrfile.append($(tmpl2.replace('#url#', files[i].name)));
}
});

/* document.write("<script src='/js/upload.js'><\/script>"); */
}

Answer 1

正确的例子：
<label for="itemKind" class="control-label col-xs-4 col-sm-3">物品种类：</label>
<div class="col-xs-4 col-sm-3">
<select class="form-control m-bot15" id="itemKind"name="itemKind"
value="${itemKind}" type="text">
<option value="0">固定资产</option>
<option value="1">低值易耗品</option>