html代码如下

<img class="sss" src="" style="border-radius:50%;width:150px;height: 150px; display: none"/>

<input name="image2" type="file" value="" />

<input type="hidden" value="" name="image"  />
jq代码如下

<script>
    $("input[type=‘file‘]").change(function () {
        if(typeof this.files == "undefined"){
            return "";
        }
        var img=this.files[0];
        var type=img.type;
        var url=getObjectURL(img);
        if(type.substr(0,5) != ‘image‘ ){
            alert("非图片");
            return;
        }
        function getObjectURL(file) {
            var url = null;
            if (window.createObjectURL != undefined) {
                url = window.createObjectURL(file)
            } else if (window.URL != undefined) {
                url = window.URL.createObjectURL(file)
            } else if (window.webkitURL != undefined) {
                url = window.webkitURL.createObjectURL(file)
            }
            return url
        };

        var reader = new FileReader();
        reader.onload = function(e) { //编码文件
            var  head = e.currentTarget.result;
            $("input[name=‘image‘]").val(head);
            $(".sss").show();
        };
        reader.readAsDataURL(this.files[0]);

        $(".sss").attr("src",url);
    });
</script>

将图片以二进制的方式上传上去，减少了服务器的内存

关于jq上传头像二进制的形式上传