<form id="myForm" action="${pageContext.request.contextPath}/uploadPicture.action" enctype="multipart/form-data" method="post">
          <input type="file" id="file1" name="image" style="display: none"/>
      </form>

    $(document).ready(function() {
         //$("#file1").hide();//隐藏
        $("#kuang").focus(function() {
            //alert("123");
            $("#file1").click();   // 选择需要上传的图片
            $("#kuang").val($("#file1").val());  // 显示出来吧
        });
        
        $("#shangchuan").bind("click", function() {
            alert("23432");
            if($("#kuang").val() == null || $("#kuang").val() == "")  {
                alert("请先点击输入框选择需要上传的图片！");    
            }else {
                // 进行提交form
                //alert("进行提交form");
                
                //$.post(url);
                $.ajax({
                    type: "post",
                    url:  "${pageContext.request.contextPath}/uploadPicture.action",
                    contentType: "multipart/form-data"
                });
                //$("#myForm").submit();
                //alert("ddd");
            }
        });
    });