SpringBoot background implements file upload and download, and springboot File Upload

SpringBoot background implements file upload and download, and springboot File Upload

How does the SpringBoot background upload and download files?

A recent project involves file upload and download. The front-end upload adopts the Baidu webUploader plug-in. The usage of this plug-in is still being studied. Record it later. This article describes how to upload and download files in the SpringBoot background.

Upload a single file

// Single file upload @ RequestMapping (value = "/upload") @ ResponseBodypublic String upload (@ RequestParam ("file") MultipartFile file) {try {if (file. isEmpty () {return "file is blank";} // get the file name String fileName = file. getOriginalFilename (); logger.info ("the uploaded file name is:" + fileName); // get the file suffix String suffixName = fileName. substring (fileName. lastIndexOf (". "); logger.info (" file Suffix: "+ suffixName); // set the file storage path String filePath = "D: // aim //"; String path = filePath + fileName + suffixName; File dest = new File (path); // check whether a directory exists if (! Dest. getParentFile (). exists () {dest. getParentFile (). mkdirs (); // create a folder} file. transferTo (dest); // return "uploaded successfully";} catch (IllegalStateException e) {e. printStackTrace ();} catch (IOException e) {e. printStackTrace ();} return "Upload Failed ";}

To modify the file path and file name, modify filePath and fileName.

Multi-File Upload

// Multifile upload @ RequestMapping (value = "/uploadMore", method = RequestMethod. POST) @ ResponseBodypublic String handleFileUpload (HttpServletRequest request) {List <MultipartFile> files = (MultipartHttpServletRequest) request ). getFiles ("file"); MultipartFile file = null; BufferedOutputStream stream = null; for (int I = 0; I <files. size (); ++ I) {file = files. get (I); String filePath = "D: // aim //"; if (! File. isEmpty () {try {byte [] bytes = file. getBytes (); stream = new BufferedOutputStream (new FileOutputStream (new File (filePath + file. getOriginalFilename (); // sets the file path and name stream. write (bytes); // write stream. close () ;}catch (Exception e) {stream = null; return "no." + I + "File Upload Failed ==>" + e. getMessage () ;}} else {return "+" + I + "File Upload failed because the file is empty" ;}} return "uploaded successfully ";}

File Download

// File download code @ RequestMapping ("/download") public String downloadFile (HttpServletRequest request, HttpServletResponse response) {String fileName = "aim_test.txt"; // set the file name, replace it with the file name to be downloaded if (fileName! = Null) {// set the File path String realPath = "D: // aim //" file File = new file (realPath, fileName); if (File. exists () {response. setContentType ("application/force-download"); // set to force download. response is not enabled. addHeader ("Content-Disposition", "attachment; fileName =" + fileName); // set the file name byte [] buffer = new byte [1024]; FileInputStream FCM = null; bufferedInputStream bis = null; try {FD = new FileInputStream (file); bis = New BufferedInputStream (FCM); OutputStream OS = response. getOutputStream (); int I = bis. read (buffer); while (I! =-1) {OS. write (buffer, 0, I); I = bis. read (buffer);} System. out. println ("success");} catch (Exception e) {e. printStackTrace ();} finally {if (bis! = Null) {try {bis. close () ;}catch (IOException e) {e. printStackTrace () ;}} if (FS! = Null) {try {fs. close ();} catch (IOException e) {e. printStackTrace () ;}}} return null ;}

MultipartConfig Configuration

You can use the MultipartConfig configuration class to globally control file uploads.

@ Configurationpublic class MultipartConfig {@ Bean public MultipartConfigElement multipartConfigElement () {MultipartConfigFactory factory = new MultipartConfigFactory (); // if the file size limit is exceeded, an exception message factory is thrown. setMaxFileSize ("2 MB"); // KB, MB // set the total size of uploaded data factory. setMaxRequestSize ("20 MB"); // sets the path of the temporary file folder // factory. setLocation ("E: // test //"); // if the file is greater than this value, it will be stored as a file. If the file is smaller than this value, it will be stored in the memory, the default value is 0 // factory. setMaxRequestSize (0); return factory. createMultipartConfig ();}}

Notes

The format of front-end and back-end file transmission should be multipart/form-data

The above is all the content of this article. I hope it will be helpful for your learning and support for helping customers.