普通的单图头像上传预览效果，比较轻巧

视图的显示，用透明度来隐藏原本点击的input=file，展示自己想要的样式

                <div style="margin-top:10px;"><button>选择图片</button> 建议尺寸：640*320，支持jpg/png/gif格式，大小不超过200K
                    <div id="repeat_file" style="width:60px;height:25px;overflow:hidden;position:relative;top:-20px;opacity:0;filter: Alpha(Opacity=0);">
                       <input type="file" style="" class="absmiddle" name="uploadedfile" id="uploadedfile"><input type=hidden name=Maxsize value=16384000>
                    </div>
                </div>

    $(function(){
        var count = -1;
        $("#repeat_file").on("change","#uploadedfile",function (){
            count++;  
//            $("#upload_status").html("图片上传中....");
            ajaxFileUpload();
            $("#uploadedfile").replaceWith("<input type='file' id='uploadedfile' class='absmiddle' name='uploadedfile' title=" + count + "' />");//重新生成新的
        });

        function ajaxFileUpload(){
            $.ajaxFileUpload({
                url:'<?= Yii::app()->createUrl("user/dealerUser/loadImage");?>',//处理上传文件的程序文件，见下面的PHP文件代码
                secureuri:false,fileElementId:'uploadedfile',dataType:'json',success:function(data){
                    if(data.msg)
                    {
                        alert(data.msg);
                    }
                    else
                    {
                        $('#mimg').attr('src','dealer/uploads/'+data.file_url).show();
                        $("#uimg").attr('value',data.file_url);
//                        $("#upload_status").html(data.file_url);
                    }
                }
            });
            return false;
        }

    })

    public function actionLoadImage()
    {
        $res["msg"] = "";//提示信息
        if(empty($_FILES) || $_FILES['uploadedfile']['error'] == 1)
        {
            $res['msg'] = "图片大小不能超过35K，请重新上传";
        }
        else
        {
            if(file_exists($_FILES['uploadedfile']['tmp_name']))
            {
                $imageName = $_FILES['uploadedfile']['name'];
                $ext = substr($imageName,strrpos($imageName,'.')+1);
//                $saveName = time() . ".".$ext;
                if(in_array(strtolower($ext),array('jpg','jpeg')))
                {
                    if($_FILES["uploadedfile"]["size"] / 1024 <= 35)
                    {
                        if(move_uploaded_file($_FILES['uploadedfile']['tmp_name'],'dealer/uploads/'.$imageName)){
                            $res['file_url'] = $imageName;
                        }
                        else
                        {
                            $res["msg"] = "文件上传失败，请重试";
                        }
                    }
                    else
                    {
                        $res['msg'] = "图片大小不能超过35K，请重新上传";
                    }
                }
                else
                {
                    $res["msg"] = "图片格式不对，请上传jpg/jpeg格式";
                }
            }
            else
            {
                $res["msg"] = "请选择要上传的文件";
            }
        }
        $res['msg'] = iconv('GB2312','UTF-8',$res['msg']);
        echo json_encode($res);
        exit();
    }