上传文件存储到数据库及下载

一、上传文件前端代码，以layui前端组件upload为例：

渲染上传按钮
<button type="button" class="layui-btn"  id="uploadDemo">选择文件</button>
做动画加载控制
<button class="layui-btn layui-btn-normal layui-btn-sm"  onclick="uploadConfirm()">确认上传</button>
文件名显示占位
<div id="fielName" ></div>

下载点击链接，excel-template-01为数据库记录具体的主键id
<a href="javascript:void(0)" onclick="exportExcel('excel-template-01')" >下载最新报价单</a>

upload.render({//上传样本信息单
            elem: '#uploadDemo'
            , url: path + '/demo/uploadFile.do'
            , auto: false //选择文件后不自动上传
            , bindAction: '#uploadConfirm' //指向一个按钮触发上传
            , accept: 'file' //普通文件
            , data: {
                channelType: 1
            }
            , choose: function (obj) {
                var files = this.files = obj.pushFile();
                //读取本地文件
                obj.preview(function (index, file, result) {
                    $("#fielName").html(file.name);
                })
            }
            , done: function (res) {
                if (res.success) {
                    layer.closeAll();
                    
                } else {
                    layer.msg(res.message);
                    layer.close(loadingIndex)
                }
            }
        });


function uploadConfirm() {
    loadingIndex = layer.load(1, {
        shade: [0.5,'#000'] //0.1透明度的背景
    });
}

window.exportExcel=function (id) {
    downloadExcel(path + '/demo/exportExcel.do',"id",id);
}
function downloadExcel(actionPath,paramName,list,paramName2,data) {
    if(list.length>0 || parseInt(list).toString() != "NaN"){
        var $eleForm = $("<form type='hidden' method='post' id='tempFrom'>" +
            "<input type='hidden' id='"+paramName+"' value='" + list + "' name='"+paramName+"' type='text' />" +
            "<input type='hidden' id='"+paramName2+"' value='" + data + "' name='"+paramName2+"' type='text' />" +
            "</form>");
        console.log($eleForm)
        $eleForm.attr("action", actionPath);
        $(document.body).append($eleForm);
        //提交表单，实现下载
        $eleForm.submit();
        $("#tempFrom").remove();//移除表单
    }else return false;

}

二、上传文件后端代码，将文件转换为二进制存入数据库

@Controller
@RequestMapping("demo")
public class FileUtilController {
@Autowired
    ExcelDataMapper excelDataMapper;

@RequestMapping(value = "/uploadFile.do", method = RequestMethod.POST)
    @ResponseBody
    public Result uploadQuotationFile(@RequestParam(value = "file", required = false) MultipartFile mfile) {
String fileName = mfile.getOriginalFilename();
        long size = mfile.getSize();
        
File file = null;
        try {
            if (mfile.equals("") || mfile.getSize() <= 0) {
                mfile = null;
            } else {
                InputStream ins = mfile.getInputStream();
                file = new File(mfile.getOriginalFilename());
//拿到文件
                getInputStream(ins, file);
                ins.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
//文件转换成二进制，入库
FileInputStream fis = new FileInputStream(file);
            FileInputStream fis2 = new FileInputStream(file);
            //将文件二进制流保存到数据库
            ExcelData excelData = new ExcelData();
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len = 0;
            while ((len = fis2.read(buffer)) != -1) {
                bos.write(buffer, 0, len);
            }

            bos.flush();
            byte[] barray = bos.toByteArray();
            excelData.setId("excel-template-01");
            excelData.setExcelData(barray);
            excelData.setExcelName(file.getName());
            excelDataMapper.updateByPrimaryKeyWithBLOBs(excelData);
            bos.close();
            fis2.close();
}
}
//工具：将ins输入流写入已命名文件file
private void getInputStream(InputStream ins, File file) {
        try {
            OutputStream os = new FileOutputStream(file);
            int bytesRead = 0;
            byte[] buffer = new byte[8192];
            while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) {
                os.write(buffer, 0, bytesRead);
            }
            os.close();
            ins.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

ExcelData.java

public class ExcelData {
    private String id;

    private String excelName;

    private byte[] excelData;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id == null ? null : id.trim();
    }

    public String getExcelName() {
        return excelName;
    }

    public void setExcelName(String excelName) {
        this.excelName = excelName == null ? null : excelName.trim();
    }

    public byte[] getExcelData() {
        return excelData;
    }

    public void setExcelData(byte[] excelData) {
        this.excelData = excelData;
    }
}

表结构

CREATE TABLE `excel_data` (
  `id` varchar(32) NOT NULL,
  `excel_data` mediumblob COMMENT '文件二进制流',
  `excel_name` varchar(128) DEFAULT NULL COMMENT 'excel的文件名',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

三、后端下载代码

@ResponseBody
    @RequestMapping(value = "/exportExcel.do", method = RequestMethod.POST)
    public void exportExcel2(@RequestParam("id") String id, HttpServletResponse response) {
        ExcelData excelData = excelDataMapper.selectByPrimaryKey(id);
        String excelName = excelData.getExcelName();
        InputStream is = new ByteArrayInputStream(excelData.getExcelData());

        try {
            response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=utf-8");
            response.setHeader("Content-Disposition", "attachment;" + "filename=" + new String(excelName.getBytes("UTF-8"), "ISO-8859-1"));
            ServletOutputStream outputStream = response.getOutputStream();
            BufferedInputStream bis = new BufferedInputStream(is);
            BufferedOutputStream bos = new BufferedOutputStream(outputStream);
            byte[] buff = new byte[8192];

            int bytesRead;
            while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
                bos.write(buff, 0, bytesRead);

            }
            bis.close();
            bos.close();
            outputStream.flush();
            outputStream.close();


        } catch (Exception e) {
            e.printStackTrace();
        }
    }