效果图：

vue组件

var setFirmLogoVue=Vue.extend({

    template: `
    <div style="height:800px;width:80%" class="text-center">
        <img :src="picUrl" alt="..." class="img-circle " style="width: 169px;height: 169px" ref='img0'>
        <p style="color:#777;margin-bottom: 30px">头像预览</p>
        <h4 style="margin-bottom: 20px">自定义头像： 选择本地照片，上传编辑自己头像</h4>
        <form id="fileForm2" enctype="multipart/form-data" class="form-horizontal row" style="margin 0 auto;">
        <div class="form-group">
            <div  class="col-md-4 col-md-offset-4 "  >
                <input  type="file"  name="file"  @change="handleFileChange" class="form-control">
            </div>
        </div>
        </form>
            <div style="color:#777;width:400px;margin: 20px auto 50px;">
                <p>
                格式： jpg、png格式
            </p>

                <p>
            大小：不超过100KB
            </p>
            </div>
        <button class="btn btn-primary" @click="uploadFirmLogo">上传头像</button>
    </div>
    `
    ,components:{

    }
    ,
    data(){
        return{
            picUrl:getCookie("firmLogo")||"/img/head.png"
        }
    },
    mounted:function(){
        var fields={};
        var ss={
            validators: {
                notEmpty: {
                    message: '请选择图片'
                },
                file: {
                    extension: 'jpeg,jpg,png',
                    type: 'image/jpeg,image/png',
                    maxSize: 10000,
                    message: '所选文件无效'
                }


            }
        }
        fields.file=ss
        formValid("fileForm2",fields)
//        $('#fileForm2').formValidation('addField', 'file', ss)//必填

    },
    methods:{

        //选择改变图片
        handleFileChange(e){
            var vm=this;
            let file = e.target.files[0];

            let supportedTypes = ['image/jpg', 'image/jpeg', 'image/png'];
            if(supportedTypes.indexOf(file.type)<0){
                layer.msg('文件格式只支持：jpg、jpeg 和 png');
                return
            }
            if(file.size>10000){
                layer.msg("大小不得超过100KB")
                return;
            }
            if (file) {
//                  this.queryFirmInfo["idPicUrl"]=URL.createObjectURL(file);
                baseFileAjax(new FormData($( "#fileForm2" )[0]),function(result){
                    if(result.ret==0){
//                          alert(result.url);
                        vm.picUrl=result.url;

                    }else{
                        layer.msg("修改图片失败！")
                    }
                })
            }
        },

        //上传地址
        uploadFirmLogo(){
            layerAjax("uploadFirmLogo",{imgFile:this.picUrl},function(result){
                $.cookie("firmLogo",this.picUrl);
            },true)
        },

formValidation的例子：
以下格式允许上传尺寸小于2 MB的JPEG，PNG图像。
编程代码

<form id="fileForm" class="form-horizontal" enctype="multipart/form-data">
    <div class="form-group">
        <label class="col-xs-3 control-label">Avatar</label>
        <div class="col-xs-6">
            <input type="file" class="form-control" name="avatar" />
        </div>
    </div>
</form>

<script>
$(document).ready(function() {
    $('#fileForm').formValidation({
        framework: 'bootstrap',
        icon: {
            valid: 'glyphicon glyphicon-ok',
            invalid: 'glyphicon glyphicon-remove',
            validating: 'glyphicon glyphicon-refresh'
        },
        fields: {
            avatar: {
                validators: {
                    notEmpty: {
                        message: 'Please select an image'
                    },
                    file: {
                        extension: 'jpeg,jpg,png',
                        type: 'image/jpeg,image/png',
                        maxSize: 2097152,   // 2048 * 1024
                        message: 'The selected file is not valid'
                    }
                }
            }
        }
    });
});
</script>

声明代码

<form id="fileForm" class="form-horizontal" enctype="multipart/form-data"
    data-fv-framework="bootstrap"
    data-fv-icon-valid="glyphicon glyphicon-ok"
    data-fv-icon-invalid="glyphicon glyphicon-remove"
    data-fv-icon-validating="glyphicon glyphicon-refresh">

    <div class="form-group">
        <label class="col-xs-3 control-label">Avatar</label>
        <div class="col-xs-6">
            <input type="file" class="form-control" name="avatar"
                data-fv-notempty="true"
                data-fv-notempty-message="Please select an image"

                data-fv-file="true"
                data-fv-file-extension="jpeg,jpg,png"
                data-fv-file-type="image/jpeg,image/png"
                data-fv-file-maxsize="2097152"
                data-fv-file-message="The selected file is not valid" />
        </div>
    </div>
</form>

<script>
$(document).ready(function() {
    $('#fileForm').formValidation();
});
</script>

formValidation官网：http://formvalidation.io/validators/file/#mime-types