使用axios获取并下载文件

/**
 * 导出文件方法
 * @param {String} method [请求方式]
 * @param {String} url [请求的url地址]
 * @param {Object} params [请求时携带的参数]
 * @param {String} fileName [导出的文件名，例：test.xlsx]
 */
function DOWNLOAD(method="post",url, params, fileName) {
    return new Promise((resolve, reject) => {
        axios({
            method: method,
            url: url,
            params: params,
            responseType: 'blob'
        })
        .then(res => {
            let reader = new FileReader();
            let data = res.data;
            reader.onload = e => {
                if (e.target.result.indexOf('Result') != -1 && JSON.parse(e.target.result).Result == false) {
                    // 进行错误处理
                } else {
                    if (!fileName) {
                        let contentDisposition = res.headers['content-disposition'];
                        if (contentDisposition) {
                            fileName = window.decodeURI(res.headers['content-disposition'].split('=')[2].split("''")[1], "UTF-8");
                        }
                    }
                    executeDownload(data, fileName);
                }
            };
            reader.readAsText(data);
            resolve(res.data);
        })
    });
}
//  模拟点击a 标签进行下载
function executeDownload(data, fileName) {
    if (!data) {
        return
    }
    let url = window.URL.createObjectURL(new Blob([data]));
    let link = document.createElement('a');
    link.style.display = 'none';
    link.href = url;
    link.setAttribute('download', fileName);
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
}