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This article is about how to use Thymeleaf to upload files in SpringBoot. I think it is very practical, so I share it with you. I hope you can get something after reading this article. Let's take a look at it.

Add dependency package org.springframework.boot spring-boot-starter-web org.springframework.boot spring-boot-starter-thymeleaf

Spring-boot-starter-thymeleaf is introduced as the page template engine.

Configuration information

Common configuration content. Units support MB or KB:

# maximum supported file spring.servlet.multipart.max-file-size=100MB# file request maximum limit spring.servlet.multipart.max-request-size=100MB

The above configuration is mainly to control the upload limit by setting the attributes of MultipartFile. MultipartFile is a wrapper class for Spring uploaded files, which contains information such as the binary stream and file attributes of the file. Relevant attributes can also be configured in the configuration file.

In addition to the above configuration, the common configuration information is as follows:

Spring.servlet.multipart.enabled=true, whether multipart is supported for uploading files

Spring.servlet.multipart.file-size-threshold=0, which supports writing files to disk

Temporary directory of files uploaded by spring.servlet.multipart.location=,

Spring.servlet.multipart.max-file-size=10Mb, maximum supported file size

Spring.servlet.multipart.max-request-sizee=10Mb, maximum request size is supported

Spring.servlet.multipart.resolve-lazily=false, whether multipart supports lazy loading when uploading files

Launch class @ SpringBootApplicationpublic class FileUploadWebApplication {public static void main (String [] args) throws Exception {SpringApplication.run (FileUploadWebApplication.class, args);} / / Tomcat large file upload connection reset @ Bean public TomcatServletWebServerFactory tomcatEmbedded () {TomcatServletWebServerFactory tomcat = new TomcatServletWebServerFactory () Tomcat.addConnectorCustomizers ((TomcatConnectorCustomizer) connector-> {if ((connector.getProtocolHandler () instanceof AbstractHttp11Protocol)) {/ /-1 means unlimited ((AbstractHttp11Protocol) connector.getProtocolHandler ()) .setMaxSwallowSize (- 1);}}); return tomcat;}}

The main purpose of the TomcatServletWebServerFactory () method is to solve the problem that the connection is reset when the uploaded file is larger than 10m, and the abnormal content cannot be captured by GlobalException.

Write a front-end page

Upload page:

Spring Boot file upload example

A very simple Post request, a selection box to select a file, a submit button, the effect is as follows:

Upload result display page:

Spring Boot-Upload Status

The effect picture is as follows:

Write upload control class

Visit localhost:8080 to automatically jump to the upload page:

@ GetMapping ("/") public String index () {return "upload";}

Upload business processing:

@ PostMapping ("/ upload") public String singleFileUpload (@ RequestParam ("file") MultipartFile file, RedirectAttributes redirectAttributes) {if (file.isEmpty ()) {redirectAttributes.addFlashAttribute ("message", "Please select a file to upload"); return "redirect:uploadStatus";} try {/ / Get the file and save it somewhere byte [] bytes = file.getBytes () / / UPLOADED_FOLDER file local storage address Path path = Paths.get (UPLOADED_FOLDER + file.getOriginalFilename ()); Files.write (path, bytes); redirectAttributes.addFlashAttribute ("message", "You successfully uploaded'" + file.getOriginalFilename () + "'");} catch (IOException e) {e.printStackTrace ();} return "redirect:/uploadStatus";}

The above code means that the file information is read through MultipartFile, if the file is empty to jump to the results page and give a prompt; if the file stream is not read empty and written to the specified directory, the result is finally displayed on the page. The most commonly used are the last two configuration contents, which limit the file upload size. An exception will be thrown if the file upload size is exceeded:

Of course, in a real project, we can first judge the file size in the business, and then display the returned information to the page.

Exception handling

What is demonstrated here is the exception handling of MultipartException, and you can also slightly modify the exception problems that monitor the entire project.

@ ControllerAdvicepublic class GlobalExceptionHandler {@ ExceptionHandler (MultipartException.class) public String handleError1 (MultipartException e, RedirectAttributes redirectAttributes) {redirectAttributes.addFlashAttribute ("message", e.getCause (). GetMessage ()); return "redirect:/uploadStatus";}} II. Upload multiple files

In a project, there is often a need to upload multiple files at a time, which we can support with a little modification.

Front-end page

First, add a page that supports uploading multiple files, as follows:

Spring Boot files upload example file 1: file 2: file 3: background processing

Add a page access entry at the backend:

@ GetMapping ("/ more") public String uploadMore () {return "uploadMore";}

Enter the URL, http://localhost:8080/more, in the browser, and you will enter this page.

MultipartFile needs to be modified to receive as an array.

@ PostMapping ("/ uploadMore") public String moreFileUpload (@ RequestParam ("file") MultipartFile [] files, RedirectAttributes redirectAttributes) {if (files.length==0) {redirectAttributes.addFlashAttribute ("message", "Please select a file to upload"); return "redirect:uploadStatus";} for (MultipartFile file:files) {try {byte [] bytes = file.getBytes () Path path = Paths.get (UPLOADED_FOLDER + file.getOriginalFilename ()); Files.write (path, bytes);} catch (IOException e) {e.printStackTrace ();}} redirectAttributes.addFlashAttribute ("message", "You successfully uploaded all"); return "redirect:/uploadStatus";}

Again, determine whether the array is empty and write the file to the specified directory after iterating through the contents of the array. Enter the URL http://localhost:8080/more in the browser and select three files for testing. When the following message appears on the page, the upload is successful.

SpringBoot-Upload StatusYou successfully uploaded all above is how to use Thymeleaf to upload files in SpringBoot. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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