通过jquery下载后端传过来的文件

1️⃣ 后端

 　　后端导过来的文件是二进制流（blob）格式，所以前端需要用blob的格式接一下这个文件

2️⃣ 前端

 3️⃣ 代码

// 表头
List<List<String>> listHead = new ArrayList<>();

@RequestMapping(value = "/exportTable", method = {RequestMethod.POST, RequestMethod.GET})
    public void export(HttpServletResponse response, @RequestParam Map<Object, Object> params) throws IOException {

        response.setContentType("application/vnd.ms-excel;charset=utf-8");
        response.setCharacterEncoding("UTF-8");

        String fileName = URLEncoder.encode("test", "UTF-8");
        response.setHeader("Content-Disposition", "attachment;filename=" + fileName + ".xlsx");

        String tableName = params.get("table").toString();
        EasyExcel.write(response.getOutputStream())
                  .registerConverter(new config())
                  .head(head1(tableName)).sheet("模板")
                  .doWrite(data(tableName
                  ));
        // 每次导出完清空listHead
        listHead.clear();
    }


public class config implements Converter<HashMap<String, Object>> {

    @Override
    public Class<HashMap> supportJavaTypeKey() {
        return HashMap.class;
    }

    @Override
    public CellDataTypeEnum supportExcelTypeKey() {
        return CellDataTypeEnum.STRING;
    }


    /**
     * 这里是写的时候会调用。/
     */
    @Override
    public WriteCellData<HashMap<String, Object>> convertToExcelData(WriteConverterContext<HashMap<String, Object>> context) {
        return new WriteCellData<HashMap<String, Object>>(String.valueOf(context.getValue()));
    }

}


private List<List<String>> head1(String tableName) {
        return listHead;
    }

private List<List<Object>> data(String tableName) {
        // 表格的动态表头
        List<String> head = new ArrayList<>();
        // 表格内的数据
        List<Map<String, Object>> dataHead = exportYxService.findAllMap(tableName);
        List<List<Object>> list = new ArrayList<>();
        Map<String, Object> mapData = new HashMap<>();
        // 取出表头
        for (int i = 0; i < dataHead.size(); i++) {
            mapData = dataHead.get(0);
        }
        for (String key : mapData.keySet()) {
            head.add(key);
        }
        for (Map<String, Object> map : dataHead) {
            List<Object> list1 = new ArrayList<>();
            for (String key : map.keySet()) {
                list1.add(map.get(key));
            }
            list.add(list1);
        }
        for (String s : head) {
            listHead.add(Collections.singletonList(s));
        }
        return list;
    }
}

// 导出按钮方法
    function Tablexport() {
        $.ajax({
            url: '../exportYxController/exportTable.json',
            type: "POST",
            data: {
                'table': tableName
            },
            // 将前端返回的数据支持blob类型
            xhr: function () {
                let xhr = new XMLHttpRequest()
                xhr.responseType = 'blob'
                return xhr
            },
            responseType: 'blob',
            success: function (res) {
                let blob = new Blob([res], {type: 'application/vnd.ms-excel'});
                let elink = document.createElement('a');
                elink.download = "test";
                elink.href = window.URL.createObjectURL(blob);
                elink.style.display = 'none';
                document.body.appendChild(elink);
                elink.click();
                document.body.removeChild(elink);
                window.URL.revokeObjectURL(blob);
            }
        })
    }