ajax文件下载

js

function _es_preDownload(id, fileName) {
    $.ajax({
        url: '${ctx}/fdAttach/download',
        type: 'post',
        async: false,
        mimeType: 'text/plain; charset=x-user-defined',//jq ajax请求文件流的方式  （起作用的重点）
        data: {id: id},
        success: function (data) {
            var rawLength = data.length;
            var array = new Uint8Array(new ArrayBuffer(rawLength));
            for (i = 0; i < rawLength; i++) {
                array[i] = data.charCodeAt(i) & 0xff;
            }
            //上面是把后台请求到的文件流进行转化为符合的流
            var blob = new Blob([array]);
            try {
                var res = $.parseJSON(data);
                if (res.code && res.code != Ajax.statusCode.ok) {
                    // 中文乱码问题
                    blob.text().then(function (res) {
                        res = $.parseJSON(res);
                        Dialog.error(res.message);
                        return;
                    });
                }
                return;
            }
            catch (e) {
            }

            Dialog.success("下载成功！");

            if ('download' in document.createElement('a')) {
                //非IE下载
                const elink = document.createElement('a');
                elink.download = fileName;
                elink.style.display = 'none';
                elink.href = URL.createObjectURL(blob);
                document.body.appendChild(elink);
                elink.click();
                URL.revokeObjectURL(elink.href);
                document.body.removeChild(elink);
            }
            else {
                navigator.msSaveBlob(blob, fileName);
            }

        }
    });
    return false;
}

java

@RequestMapping("/download")
public void download(String id, HttpServletResponse response)
    throws Exception {
    FileInfo fileInfo = fdAttachService.download(id);
    InputStream is = fileInfo.getInputStream();
    response.setContentType("application/force-download");
    IOUtils.copy(is, response.getOutputStream());
}