猿创征文｜Java下载文件到本地目录(弹框选择)

需求

提供一个接口,前端通过按钮下载文件,根据不同的id下载对应的文件

编写接口相关代码

controller

/**
     * 下载文件
     *
     * @param signId
     */@GetMapping("/downloadFile")@ApiOperationSupport(order =5)@ApiOperation(value ="下载文档", notes ="传入signId")publicvoiddownloadFile(@ApiParam(value ="签署id", required =true)@RequestParamLong signId,HttpServletResponse response)throwsException{
        signDocumentService.downloadFile(signId,response);}

mapper

/**
     * 根据singId查询Attach
     *
     * @param singId
     * @return SignDocument
     */List<Map<String,String>>selectAttachs(@Param("singId")Long singId);

mapper.xml

<select id="selectAttachs" resultType="map">
        select
            ba.link filePath,ba.original_name fileName
        from dmyz_sign_document dsd
        left join blade_attach ba on ba.id=dsd.attach_id
        where sign_id =#{singId} and  dsd.is_deleted =0</select>

service

/**
     * 根据id查询附件并下载
     *
     * @param signId
     * @param response
     * @throws Exception
     */voiddownloadFile(Long signId,HttpServletResponse response)throwsIOException;

serviceImpl

这里我要从oss上下载,所以我先从oss下载到项目本地了,不然File无法识别远程文件,只能识别本地文件,这块逻辑自行修改,代码参考即可

/**
     * 根据id查询附件并下载
     *
     * @param signId
     * @param response
     * @throws Exception
     */@OverridepublicvoiddownloadFile(Long signId,HttpServletResponse response)throwsIOException{String path =null;String download =null;ServletOutputStream out=null;FileInputStream fis=null;try{// 根据signId查询签署文档List<Map<String,String>> maps = signDocumentMapper.selectAttachs(signId);// 如果不为空if(!maps.isEmpty()){for(Map<String,String> map : maps){String link =  map.get("filePath");String uuid = UUID.randomUUID().toString().replace("-","");// 文件名称 uuid随机生成String fileName =uuid+PDF;// 把oss文件下载到项目本地
                    path =SignDocumentServiceImpl.class.getClass().getResource("/").getPath()+FileUtil.getNameWithoutExtension(link)+ PDF;// 把获取到的oss文件链接下载到本地
                    download =download(link, path);File file =newFile(download);
                    response.setCharacterEncoding("utf-8");
                    response.setContentType("application/file");
                    response.setHeader("Content-Disposition","attachment;FileName="+ fileName);
                    out = response.getOutputStream();int len =0;byte[] buffer =newbyte[1024];
                    fis =newFileInputStream(file);while((len = fis.read(buffer))>0){
                        out.write(buffer,0, len);
                        out.flush();}
                    response.flushBuffer();}}}catch(Exception e){
            log.error("下载单个pdf文件失败,原因:{}", e);}finally{
            out.close();
            fis.close();}}

访问接口测试

浏览器输入

localhost:8080/downloadFile?signId=1001

本地选择保存目录

点击保存 就看到在指定的位置上有我们的文件了

可以正常打开查看