springboot业务功能实战（十五）以流的方式对文件上传下载

• java

      @Controller
      public class FileController {
         @RequestMapping(value = "/fileuploads")
         public String toFileUpload() {
             return "fileupload";
          }
         @RequestMapping(value = "/fileupload")
         public String fileUpload(@RequestParam(value = "file") List<MultipartFile> files, HttpServletRequest request) {
             String msg = "";
             // 判断文件是否上传
             if (!files.isEmpty()) {
                 // 设置上传文件的保存目录
                 String basePath = request.getServletContext().getRealPath("/upload/");
                 // 判断文件目录是否存在
                  File uploadFile = new File(basePath);
                 if (!uploadFile.exists()) {
                      uploadFile.mkdirs();
                  }
                 for (MultipartFile file : files) {
                     String originalFilename = file.getOriginalFilename();
                     if (originalFilename != null && !originalFilename.equals("")) {
                         try {
                             // 对文件名做加UUID值处理
                              originalFilename = UUID.randomUUID() + "_" + originalFilename;
                              file.transferTo(new File(basePath + originalFilename));
                          } catch (IOException e) {
                              e.printStackTrace();
                              msg = "文件上传失败！";
                          }
                      } else {
                          msg = "上传的文件为空！";
                      }
                  }
                  msg = "文件上传成功！";
              } else {
                  msg = "没有文件被上传！";
              }
              request.setAttribute("msg", msg);
             return "chatroom";
          }
         @ExceptionHandler(MaxUploadSizeExceededException.class)
         public String handException(MaxUploadSizeExceededException e, HttpServletRequest request) {
      // System.out.println("我捕获了异常");
              request.setAttribute("msg", "文件超过了指定大小，上传失败！");
             return "fileupload";
          }
         @RequestMapping(value = "/filedownload")
         public String toFileDownload(HttpServletRequest request) {
             return "filedownload";
          }
         @RequestMapping(value = "/fileList")
         @ResponseBody
         public String fileList(HttpServletRequest request) {
             String baseDir = request.getServletContext().getRealPath("/upload");
              File baseFile = new File(baseDir);
              List<String> fileList = null;
             if (baseFile.exists()) {
                  File[] files = baseFile.listFiles();
                  fileList = new ArrayList<>(files.length);
                 for (File file : files) {
                      fileList.add(file.getName());
                  }
              }
      // System.out.println(fileList.toString());
             String json = JSON.toJSONString(fileList);
             return json;
          }
         @RequestMapping(value = "/download")
         public ResponseEntity<byte[]> fileDownload(String filename, HttpServletRequest request) throws IOException {
             String path = request.getServletContext().getRealPath("/upload/");
              File file = new File(path + filename);
              System.out.println("转码前" + filename);
              filename = this.getFilename(request, filename);
              System.out.println("转码后" + filename);
             // 设置响应头通知浏览器下载
              HttpHeaders headers = new HttpHeaders();
             // 将对文件做的特殊处理还原
              filename = filename.substring(filename.indexOf("_") + 1);
              headers.setContentDispositionFormData("attachment", filename);
              headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
             return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file), headers, HttpStatus.OK);
          }
         // 根据不同的浏览器进行编码设置，返回编码后的文件名
         public String getFilename(HttpServletRequest request, String filename) throws UnsupportedEncodingException {
             String[] IEBrowerKeyWords = {"MSIE", "Trident", "Edge"};
             String userAgent = request.getHeader("User-Agent");
             for (String keyword : IEBrowerKeyWords) {
                 if (userAgent.contains(keyword)) {
                     return URLEncoder.encode(filename, "UTF-8");
                  }
              }
             return new String(filename.getBytes("UTF-8"), "ISO-8859-1");
          }
      }
  
 

• js

      $(function(){
     		var targer = $("#main2")
      		$.ajax({
     			url: "fileList",
     			dataType: "json",
     			success: function (data) {
     				for (var i in data) {
     					var a = $("<a></a><br>").text(data[i].substring(data[i].indexOf("_")+1))
      					a.attr("href", "${pageContext.request.contextPath}/download?filename="+encodeURIComponent(data[i]))
      					targer.append(a)
      					alert(targer)
      				}
      			}
      		})
      	}
  
 

      function check() {
     		var file = document.getElementById("file");
     		if (file.value == "") {
      			alert("上传的文件为空")
     			return false;
      		}
     		return true;
      	}
  
 

• jsp

      <div id="main" style="width:500px; margin: 0 auto;">
     				<form action="fileupload" method="post" enctype="multipart/form-data" onsubmit="return check()">
     					<input type="file" name="file" id="file" multiple="multiple"><br>
     					<input type="submit" value="上传">
     				</form>
     			</div>
     			<div id="main2" style="width:500px; margin: 0 auto;">
     			</div>
  
 

文章来源: baocl.blog.csdn.net，作者：小黄鸡1992，版权归原作者所有，如需转载，请联系作者。

原文链接：baocl.blog.csdn.net/article/details/101749711