主要代码

        // base64转blob
           function base64ToBlob(code) {
                let parts = code.split(';base64,');
                let contentType = parts[0].split(':')[1];
                let raw = window.atob(parts[1]);
                let rawLength = raw.length;
                let uInt8Array = new Uint8Array(rawLength);
                for(let i = 0; i < rawLength; ++i) {
                    uInt8Array[i] = raw.charCodeAt(i);
                }
                return new Blob([uInt8Array], {type: contentType});
            }

完整代码

<?xml version="1.0" encoding="UTF-8"?>
<a:screen xmlns:a="http://www.aurora-framework.org/application">
    <a:view>
        <script><![CDATA[
            function query(){
                $('query_cosoc_credit_data_result_ds').query();
            }
            function export_excel(){
                $('query_cosoc_credit_data_result_ds_grid')._export();
            }
           function formatNumber(value){
                if(value==0)
                    return '纸质';
                else
                    return '电子';
            }


            // 征信授权书下载
            function downLoadTorenderercredit_auth_power(value, record, name){
                if (value){
                    if (value.length > 20){
                         return '<a href="javascript:downLoadTo(\'征信授权书\',\'' + value + '\')">征信授权书下载</a>';
                    }

                }

            }

            // 面签照下载
            function downLoadTorendererinterview(value, record, name){
                if (value){
                    if (value.length > 20){
                                        return '<a href="javascript:downLoadTo(\'面签照\',\'' + value + '\')">面签照下载</a>';
                    }
                }
            }
            function downLoadTo(name,value) {
                if(!!value) {
                    let imgData = value;
                    var fileName = name+'.jpg';
                    if (value.indexOf("data:application/pdf") != -1){
                        fileName = name+'.pdf';
                    }
                    this.downloadFile(fileName, imgData);
                }
            }

            // 下载
            function downloadFile(fileName, content) {
                let aLink = document.createElement('a');
                let blob = base64ToBlob(content); // new Blob([content]);
                let evt = document.createEvent('HTMLEvents');
                evt.initEvent('click', true, true);// initEvent 不加后两个参数在FF下会报错  事件类型，是否冒泡，是否阻止浏览器的默认行为
                aLink.download = fileName;
                aLink.href = URL.createObjectURL(blob);
                aLink.dispatchEvent(new MouseEvent('click', {bubbles: true, cancelable: true, view: window}));// 兼容火狐
            }

            // base64转blob
           function base64ToBlob(code) {
                let parts = code.split(';base64,');
                let contentType = parts[0].split(':')[1];
                let raw = window.atob(parts[1]);
                let rawLength = raw.length;

                let uInt8Array = new Uint8Array(rawLength);

                for(let i = 0; i < rawLength; ++i) {
                    uInt8Array[i] = raw.charCodeAt(i);
                }
                return new Blob([uInt8Array], {type: contentType});
            }
        ]]></script>
        <a:dataSets>
            <a:dataSet id="query_ds">
                <a:fields>
                    <a:field name="custname"/>
                    <a:field name="business_no"/>
                    <a:field name="loan_stat_des" displayField="code" options="loan_stat_ds" returnField="loan_stat" valueField="value"/>
                    <a:field name="loan_stat"/>
                </a:fields>
            </a:dataSet>
            <a:dataSet id="query_cosoc_credit_data_result_ds" autoQuery="true" model="crdt.CRDTZYH.query_cosoc_credit_data" pageSize="15" queryDataSet="query_ds" selectable="true" selectionModel="single"><![CDATA[
            ]]></a:dataSet>
        </a:dataSets>
        <a:screenBody>
            <a:screenTopToolbar>
                <a:screenTitle/>
                <a:gridButton click="query" text="HLS.QUERY"/>
                <a:gridButton click="export_excel" text="导出"/>
            </a:screenTopToolbar>
            <a:form column="4" labelWidth="100" marginWidth="30" title="查询条件">
                <a:textField name="name" bindTarget="query_ds" prompt="姓名"/>
                <a:textField name="id_card" bindTarget="query_ds" prompt="身份证号"/>
            </a:form>
            <a:grid id="query_cosoc_credit_data_result_ds_grid" bindTarget="query_cosoc_credit_data_result_ds" marginHeight="180" marginWidth="30" navBar="true">
                <a:toolBar>
                    <a:button  text="下载征信授权书" />
                    <a:button text="下载面签照" />
                </a:toolBar>
                <a:columns>
                    <a:column name="name" prompt="姓名"/>
                    <a:column name="id_card_no" prompt="身份证号"/>
                    <a:column name="bank_card_no" prompt="银行卡号"/>
                    <a:column name="sign_type" prompt="签约类型" renderer="formatNumber" />
                    <a:column name="query_id" prompt="查询id"/>
                    <a:column name="creation_date" prompt="查询时间" renderer="Aurora.formatDate"/>
                    <a:column name="credit_auth_power" prompt="征信授权书" renderer="downLoadTorenderercredit_auth_power" />
                    <a:column name="interview" prompt="面签照" renderer="downLoadTorendererinterview" />

                </a:columns>
            </a:grid>
        </a:screenBody>
    </a:view>
</a:screen>