1、引入必要的css，js

<link rel="stylesheet" th:href="@{/resources/bootstrap/css/bootstrap.min.css}">
    <link rel="stylesheet" th:href="@{/resources/awi/plugins/bootstrapvalidator/css/bootstrapValidator.min.css}">
    <script th:src="@{/resources/awi/plugins/jQuery/jquery-2.2.3.min.js}"></script>
    <script th:src="@{/resources/awi/plugins/bootstrapvalidator/js/bootstrapValidator.js}"></script>

2、对应的html

<div class="form-group">
        <label class="col-xs-2 control-label">提交凭证</label>
        <div class="col-xs-8">
            <input type="file"  class="hidden" name="voucherFile" id="voucherFile" οnchange="changepic('voucherFile')">
            <img src="/front/img/head.jpg" style="width: 20%;height: 20%;" id="img" οnclick="getPicture('voucherFile')">
        </div>
    </div>

3、对应的js

initValidator();

    function add() {

        var bootstrapValidator = $('#reportForm').data('bootstrapValidator').validate();

        if (bootstrapValidator.isValid()) {
            var formdata = new FormData($("#reportForm")[0]);
            form("/index/reportrecord/add",formdata,function (data) {

                if (data.code == 0){
                    layer.msg("举报成功！",{time:2000},function () {
                        parent.layer.closeAll();
                    });
                }else{
                    layer.msg("系统错误！",{time:2000},function () {

                    });
                }

            })
        }
    }
    function initValidator() {
        $('#reportForm').bootstrapValidator({
            message: '输入值不满足要求',
            excluded : [':disabled'],
            verbose:false,//verbose为false表示一个字段的多个验证规则中，如果有一个验证不通过则继续去验证其他的字段 在0.5.2版本生效
            fields: {
                content: {
                    validators: {
                        notEmpty: {
                            message: '必填'
                        },
                        stringLength: {
                            max: 255,
                            message: '不能超过50位'
                        }
                    }
                },
                voucherFile: {
                    // group: '.col-xs-12',
                    trigger:"change",
                    validators: {
                        notEmpty: {
                            message: '凭证不能为空！'
                        },
                        file: {
                            extension: 'jpeg,jpg,png',
                            type: 'image/jpg,image/jpeg,image/png,',
                            maxSize: 2*1024*1024,
                            message: '允许上传的jpg、png且大小不能超过2M'
                        }
                    }
                },
            }
        });
    }

    function changepic(voucherFile) {

        $('#reportForm').data('bootstrapValidator').updateStatus("voucherFile",  "NOT_VALIDATED",  null );

        $("#reportForm").data('bootstrapValidator').validateField('voucherFile');
        if ($("#reportForm").data('bootstrapValidator').isValidField("voucherFile")){

            var reads = new FileReader();
            f = document.getElementById(voucherFile).files[0];
            reads.readAsDataURL(f);
            reads.onload = function (e) {
                document.getElementById('img').src = this.result;
            }
        }

    }

    function getPicture(id) {
        document.getElementById(id).click();
    }