文件上传和下载

1.文件上传前端用fileupload后端这样上传到服务器

/**
 * @author zhenglong
 * @Description: 巡检任务的上传
 * @Date 2019/6/26 13:21
 */
@RestController
public class UploadExcelController extends HttpServlet {
    @Value("${uploadexcel.file.path}")
    private String uploadExcelFilePath ;
    @Autowired
    private TaskService taskService;

    @PostMapping("/upload")
    @ResponseBody
    public ServerResponse upload(HttpServletRequest request, HttpServletResponse response,@RequestParam("taskId") Integer taskId) {
        //如果没有任务的id直接返回
         if(taskId==0 || taskId==null){
             return ResponseUtil.business_error(1003, "传参数错误");
         }
        String saveUrl = uploadExcelFilePath;
        //定义允许上传的文件扩展名
        HashMap<String, String> extMap = new HashMap<String, String>();
        extMap.put("file", "doc,docx,xls,xlsx,txt");
        // 设置文件上传大小,单位kb
        long maxSize = 20480;

        response.setContentType("text/html; charset=UTF-8");
        // 判断是否是文件上传的request
        if (!ServletFileUpload.isMultipartContent(request)) {
            return ResponseUtil.business_error(404, "请选择文件。");
        }
        //检查目录  d:\\upload
//        saveUrl = "D:\\upload/";
        File uploadDir = new File(saveUrl);

        if (!uploadDir.isDirectory()) {
            return ResponseUtil.business_error(404, "上传目录不存在。");
        }
        //检查目录写权限
        if (!uploadDir.canWrite()) {
            return ResponseUtil.business_error(400, "上传目录没有写权限。");
        }
        // dir:image
        String dirName = request.getParameter("dir");
        // 如果dirname为空，默认file
        if (dirName == null) {
            dirName = "file";
        }
        // 判断dirName是否在extMap存在
        if (!extMap.containsKey(dirName)) {
            return ResponseUtil.business_error(400, "目录名不正确。");
        }

        saveUrl += dirName + "/";
        //  创建加上时间之后的文件夹
        File dirFile = new File(saveUrl);
        // 如果文件夹不存在，则创建
        if (!dirFile.exists()) {
            dirFile.mkdirs();
        }
        // 创建上传文件的保存的工厂
        MultipartHttpServletRequest servletRequest = (MultipartHttpServletRequest) request;
        // 获取上传的多个文件的名字
        Iterator<String> iterator = servletRequest.getFileNames();
        // 遍历名字
        while (iterator.hasNext()) {
            // 获取文件的名字
            String fileName = iterator.next();
            // 获取文件
            MultipartFile file = servletRequest.getFile(fileName);
            //检查文件大小
            if (file.getSize() > maxSize) {
                return ResponseUtil.business_error(500, "上传文件大小超过限制。");
            }
            //检查扩展名
            String ext = file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf(".") + 1).toLowerCase();
            // 判断后缀名在对应的类型中是否存在
            if (!extMap.get(dirName).contains(ext)) {
                return ResponseUtil.business_error(500, "上传文件扩展名是不允许的扩展名。\n只允许" + extMap.get(dirName) + "格式。");
            }
            // 给文件随机一个名字
            String filename = file.getOriginalFilename().substring(0, file.getOriginalFilename().lastIndexOf(".")).toLowerCase();
            SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss");
            String newFileName = filename+ "("+df.format(new Date()) +")" + "." + ext;
            // 复制内容
            try {
                //把文件名字存入数据库中
              Boolean flag=  taskService.updatePath(taskId,newFileName);
              if(flag){
                  File uploadedFile = new File(saveUrl, newFileName);
                  file.transferTo(uploadedFile);
              }
            } catch (Exception e) {
                return ResponseUtil.business_error(500, "上传文件失败。");
            }
            //上传文件返回的信息
            HashMap<String, Object> map = new HashMap<>();
            map.put("error", 0);
            map.put("url", newFileName);
            return ResponseUtil.success(map);

        }

        return null;
    }


 


}

2文件下载，前端用location.href这样请求后台的方法即可后端代码如下

/**
 * @author zhenglong
 * @Description: 浏览器下载文件
 * @Date 2019/6/29 19:04
 */

import com.auth0.jwt.internal.org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

@RestController
public class DownloadController {
    @Value("${downloadexcel.file.path}")
    private String downloadFilePath;
    /**
     * 文件下载的方法，需要传下载文件的名字
     * @param response
     * @param request
     */
    @GetMapping("/download")
    public void download(HttpServletResponse response, HttpServletRequest request) {
        String url = downloadFilePath;
//        url ="D:\\upload\\file";
        String file = request.getParameter("name");
        if (!StringUtils.isNotBlank(file)) {
            return;
        }
        url +="/"+ file;
        if (url != null && url != "") {
            String fileName = url.substring(url.lastIndexOf("/") + 1).toLowerCase();
            try {
                this.prototypeDownload(new File(url), fileName, response, false,request);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * @param file       要下载的文件
     * @param returnName 返回的文件名
     * @param response   HttpServletResponse
     * @param delFlag    是否删除文件
     */
    private void prototypeDownload(File file, String returnName, HttpServletResponse response, boolean delFlag,HttpServletRequest request) {
        // 下载文件
        FileInputStream inputStream = null;
        ServletOutputStream outputStream = null;
        try {
            if (!file.exists()) return;
            response.reset();
            //设置响应类型	PDF文件为"application/pdf"，WORD文件为："application/msword"， EXCEL文件为："application/vnd.ms-excel"。
            response.setContentType("application/octet-stream;charset=utf-8");
              String agent =request.getHeader("USER-AGENT");

              if(agent !=null && agent.indexOf("Mozilla") != -1){
                  //保存的文件名,必须和页面编码一致,否则乱码
                  returnName = response.encodeURL(new String(returnName.getBytes("utf-8"), "iso-8859-1"));
              }else{
                  //设置响应的文件名称,并转换成中文编码
                  returnName = URLEncoder.encode(returnName, "UTF-8");
              }


            //attachment作为附件下载；inline客户端机器有安装匹配程序，则直接打开；注意改变配置，清除缓存，否则可能不能看到效果
            response.addHeader("Content-Disposition", "attachment;filename=" + returnName);

            //将文件读入响应流
            inputStream = new FileInputStream(file);
            outputStream = response.getOutputStream();
            int length = 1024;
            int readLength = 0;
            byte buf[] = new byte[1024];
            readLength = inputStream.read(buf, 0, length);
            while (readLength != -1) {
                outputStream.write(buf, 0, readLength);
                readLength = inputStream.read(buf, 0, length);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                outputStream.flush();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            //删除原文件

            if (delFlag) {
                file.delete();
            }
        }
    }