1.传统方法

    @RequestMapping("/download")

		public String download( String fileName ,String filePath, HttpServletRequest request, HttpServletResponse response){

			response.setContentType("text/html;charset=utf-8");

			try {

				request.setCharacterEncoding("UTF-8");

			} catch (UnsupportedEncodingException e1) {

				// TODO Auto-generated catch block

				e1.printStackTrace();

			}

			java.io.BufferedInputStream bis = null;

			java.io.BufferedOutputStream bos = null;

			String downLoadPath = filePath;  //注意不同系统的分隔符

		//	String downLoadPath =filePath.replaceAll("/", "\\\\\\\\");   //replace replaceAll区别 *****

			System.out.println(downLoadPath);

			try {

				long fileLength = new File(downLoadPath).length();

				response.setContentType("application/x-msdownload;");

				response.setHeader("Content-disposition", "attachment; filename=" + new String(fileName.getBytes("utf-8"), "ISO8859-1"));

				response.setHeader("Content-Length", String.valueOf(fileLength));

				bis = new BufferedInputStream(new FileInputStream(downLoadPath));

				bos = new BufferedOutputStream(response.getOutputStream());

				byte[] buff = new byte[2048];

				int bytesRead;

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

					bos.write(buff, 0, bytesRead);

				}

			} catch (Exception e) {

				e.printStackTrace();

			} finally {

				if (bis != null)

					try {

						bis.close();

					} catch (IOException e) {

						// TODO Auto-generated catch block

						e.printStackTrace();

					}

				if (bos != null)

					try {

						bos.close();

					} catch (IOException e) {

						// TODO Auto-generated catch block

						e.printStackTrace();

					}

			}

			return null;

		}

2.利用springmvc提供的ResponseEntity类型,使用它可以很方便地定义返回的HttpHeaders和HttpStatus。

        @RequestMapping("/download")

	    public ResponseEntity<byte[]> export(String fileName,String filePath) throws IOException {  

	        HttpHeaders headers = new HttpHeaders();

	        File file = new File(filePath);

	        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);

	        headers.setContentDispositionFormData("attachment", fileName);    

	        return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),

	                                              headers, HttpStatus.CREATED);

	    } 

3、多文件下载[2]

主要先下载到本地，并添加到压缩文件中，再读取压缩文件到数组中，而后将数组返回前台返回前台

//批量文件压缩后下载

	@RequestMapping("/downLoad2")

	public ResponseEntity<byte[]> download2(HttpServletRequest request) throws IOException {

		//需要压缩的文件

		List<String> list = new ArrayList<String>();

		list.add("test.txt");

		list.add("test2.txt");

		//压缩后的文件

		String resourcesName = "test.zip";

		ZipOutputStream zipOut = new ZipOutputStream(new FileOutputStream("D:/"+resourcesName));

		InputStream input = null;

		for (String str : list) {

			String name = "D:/"+str;

			input = new FileInputStream(new File(name));

            zipOut.putNextEntry(new ZipEntry(str));

            int temp = 0;

            while((temp = input.read()) != -1){

                zipOut.write(temp);

            }

            input.close();

		}

		zipOut.close();

		File file = new File("D:/"+resourcesName);

		HttpHeaders headers = new HttpHeaders();

		String filename = new String(resourcesName.getBytes("utf-8"),"iso-8859-1");

		headers.setContentDispositionFormData("attachment", filename);

		headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);

		return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),headers,HttpStatus.CREATED);

	}

另外需要注意的一点

ajax请求无法响应下载功能因为response原因，一般请求浏览器是会处理服务器输出的response，例如生成png、文件下载等,然而ajax请求只是个“字符型”的请求，即请求的内容是以文本类型存放的。文件的下载是以二进制形式进行的，虽然可以读取到返回的response，但只是读取而已，是无法执行的，说白点就是js无法调用到浏览器的下载处理机制和程序。

推荐使用这种方式 自己构建表单进行提交

var form = $("<form>");

form.attr("style","display:none");

form.attr("target","");

form.attr("method","post");

form.attr("action",rootPath + "T_academic_essay/DownloadZipFile.do");

var input1 = $("<input>");

input1.attr("type","hidden");

input1.attr("name","strZipPath");

input1.attr("value",strZipPath);

$("body").append(form);

form.append(input1);

form.submit();

form.remove();

原文出处：

[1] panpanpan_, SpringMVC实现文件下载的两种方式, https://blog.csdn.net/a447332241/article/details/78998239

[2] qq_33422712, SpringMvc 下载和批量下载, https://blog.csdn.net/qq_33422712/article/details/79142350