Two ways to implement file download in SpringMVC

1. Conventional method

    @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. Using the ResponseEntity type provided by springmvc, you can use it to easily define the returned HttpHeaders and 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);    
	    } 

Another thing to note

The ajax request cannot respond to the download function. Because of the response, the browser generally requests the response from the server, such as generating png, file download, etc. However, the ajax request is only a "character" request, that is, the requested content is in text type Stored. The file is downloaded in binary form. Although the returned response can be read, it is only read and cannot be executed. The white point is that js cannot call the browser's download processing mechanism and program.

It is recommended to use this method to build your own form for submission

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();