Mvc Upload File Stream Not Read Again

In this tutorial, I will show you how to upload and download files with a Spring Boot Rest APIs to/from a static folder. We also use Spring Web MultipartFile interface to handle HTTP multi-part requests.

This Spring Boot App works with:
– Angular 8 Client / Angular 10 Client / Angular 11 Client / Angular 12
– Angular Material 12
– Vue Client / Vuetify Client
– React Client / React Hooks Client
– Material UI Client
– React Image Upload with Preview
– Axios Client

Related Posts:
– How to upload multiple files in Java Spring Boot
– Spring Boot: Upload/Import Excel file data into MySQL Database
– Spring Boot: Upload/Import CSV file data into MySQL Database

Deployment: Deploy Spring Boot App on AWS – Elastic Beanstalk

Spring Boot Rest APIs for uploading Files

Our Spring Boot Application will provide APIs for:

• uploading File to a static folder in the Server
• downloading File from server with the link
• getting list of Files' information (file name & url)

These are APIs to be exported:

Methods	Urls	Actions
POST	/upload	upload a File
GET	/files	get List of Files (name & url)
GET	/files/[filename]	download a File

This is the static folder that stores all uploaded files:

If you want to store files in database like this:

You can find instruction at:
Spring Boot Upload/Download File to/from Database example

Technology

• Java 8
• Spring Boot 2 (with Spring Web MVC)
• Maven 3.6.1

Project Structure

Let me explain it briefly.

– FileInfo contains information of the uploaded file.
– FilesStorageService helps us to initialize storage, save new file, load file, get list of Files' info, delete all files.
– FilesController uses FilesStorageService to export Rest APIs: POST a file, GET all files' information, download a File.
– FileUploadExceptionAdvice handles exception when the controller processes file upload.
– application.properties contains configuration for Servlet Multipart.
– uploads is the static folder for storing files.
– pom.xml for Spring Boot dependency.

Setup Spring Boot project

Use Spring web tool or your development tool (Spring Tool Suite, Eclipse, Intellij) to create a Spring Boot project.

Then open pom.xml and add these dependencies:

          <dependency>   <groupId>org.springframework.boot</groupId>   <artifactId>spring-boot-starter-web</artifactId> </dependency>                  

Create Service for File Storage

First we need an interface that will be autowired in the Controller.
In service folder, create FilesStorageService interface like following code:

service/FilesStorageService.java

          package com.bezkoder.spring.files.upload.service; import java.nio.file.Path; import java.util.stream.Stream; import org.springframework.core.io.Resource; import org.springframework.web.multipart.MultipartFile; public interface FilesStorageService {   public void init();   public void save(MultipartFile file);   public Resource load(String filename);   public void deleteAll();   public Stream<Path> loadAll(); }                  

Now we create implementation of the interface.

service/FilesStorageServiceImpl.java

          package com.bezkoder.spring.files.upload.service; import java.io.IOException; import java.net.MalformedURLException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.stream.Stream; import org.springframework.core.io.Resource; import org.springframework.core.io.UrlResource; import org.springframework.stereotype.Service; import org.springframework.util.FileSystemUtils; import org.springframework.web.multipart.MultipartFile; @Service public class FilesStorageServiceImpl implements FilesStorageService {   private final Path root = Paths.get("uploads");   @Override   public void init() {     try {       Files.createDirectory(root);     } catch (IOException e) {       throw new RuntimeException("Could not initialize folder for upload!");     }   }   @Override   public void save(MultipartFile file) {     try {       Files.copy(file.getInputStream(), this.root.resolve(file.getOriginalFilename()));     } catch (Exception e) {       throw new RuntimeException("Could not store the file. Error: " + e.getMessage());     }   }   @Override   public Resource load(String filename) {     try {       Path file = root.resolve(filename);       Resource resource = new UrlResource(file.toUri());       if (resource.exists() || resource.isReadable()) {         return resource;       } else {         throw new RuntimeException("Could not read the file!");       }     } catch (MalformedURLException e) {       throw new RuntimeException("Error: " + e.getMessage());     }   }   @Override   public void deleteAll() {     FileSystemUtils.deleteRecursively(root.toFile());   }   @Override   public Stream<Path> loadAll() {     try {       return Files.walk(this.root, 1).filter(path -> !path.equals(this.root)).map(this.root::relativize);     } catch (IOException e) {       throw new RuntimeException("Could not load the files!");     }   } }                  

Define Data Models

Let's create FileInfo model which has fields: name & url.

model/FileInfo.java

          package com.bezkoder.spring.files.upload.model; public class FileInfo {   private String name;   private String url;   public FileInfo(String name, String url) {     this.name = name;     this.url = url;   }   public String getName() {     return this.name;   }   public void setName(String name) {     this.name = name;   }   public String getUrl() {     return this.url;   }   public void setUrl(String url) {     this.url = url;   } }                  

Define Response Message

The ResponseMessage is for message to client that we're gonna use in Rest Controller and Exception Handler.

message/ResponseMessage.java

          package com.bezkoder.spring.files.upload.message; public class ResponseMessage {   private String message;   public ResponseMessage(String message) {     this.message = message;   }   public String getMessage() {     return message;   }   public void setMessage(String message) {     this.message = message;   } }                  

Create Controller for upload & download Files

In controller package, we create FilesController.

controller/FilesController.java

          package com.bezkoder.spring.files.upload.controller; import java.util.List; import java.util.stream.Collectors; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.core.io.Resource; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.CrossOrigin; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.multipart.MultipartFile; import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder; import com.bezkoder.spring.files.upload.model.FileInfo; import com.bezkoder.spring.files.upload.model.ResponseMessage; import com.bezkoder.spring.files.upload.service.FilesStorageService; @Controller @CrossOrigin("http://localhost:8081") public class FilesController {   @Autowired   FilesStorageService storageService;   @PostMapping("/upload")   public ResponseEntity<ResponseMessage> uploadFile(@RequestParam("file") MultipartFile file) {     String message = "";     try {       storageService.save(file);       message = "Uploaded the file successfully: " + file.getOriginalFilename();       return ResponseEntity.status(HttpStatus.OK).body(new ResponseMessage(message));     } catch (Exception e) {       message = "Could not upload the file: " + file.getOriginalFilename() + "!";       return ResponseEntity.status(HttpStatus.EXPECTATION_FAILED).body(new ResponseMessage(message));     }   }   @GetMapping("/files")   public ResponseEntity<List<FileInfo>> getListFiles() {     List<FileInfo> fileInfos = storageService.loadAll().map(path -> {       String filename = path.getFileName().toString();       String url = MvcUriComponentsBuilder           .fromMethodName(FilesController.class, "getFile", path.getFileName().toString()).build().toString();       return new FileInfo(filename, url);     }).collect(Collectors.toList());     return ResponseEntity.status(HttpStatus.OK).body(fileInfos);   }   @GetMapping("/files/{filename:.+}")   @ResponseBody   public ResponseEntity<Resource> getFile(@PathVariable String filename) {     Resource file = storageService.load(filename);     return ResponseEntity.ok()         .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + file.getFilename() + "\"").body(file);   } }                  

– @CrossOrigin is for configuring allowed origins.
– @Controller annotation is used to define a controller.
– @GetMapping and @PostMapping annotation is for mapping HTTP GET & POST requests onto specific handler methods:

• POST /upload: uploadFile()
• GET /files: getListFiles()
• GET /files/[filename]: getFile()

– We use @Autowired to inject implementation of FilesStorageService bean to local variable.

Configure Multipart File for Servlet

Let's define the maximum file size that can be uploaded in application.properties as following:

          spring.servlet.multipart.max-file-size=500KB spring.servlet.multipart.max-request-size=500KB                  

– spring.servlet.multipart.max-file-size: max file size for each request.
– spring.servlet.multipart.max-request-size: max request size for a multipart/form-data.

Handle File Upload Exception

This is where we handle the case in that a request exceeds Max Upload Size. The system will throw MaxUploadSizeExceededException and we're gonna use @ControllerAdvice with @ExceptionHandlerannotation for handling the exceptions.

exception/FileUploadExceptionAdvice.java

          package com.bezkoder.spring.files.upload.exception; import org.springframework.web.multipart.MaxUploadSizeExceededException; import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler; import com.bezkoder.spring.files.upload.model.ResponseMessage; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.ControllerAdvice; import org.springframework.web.bind.annotation.ExceptionHandler; @ControllerAdvice public class FileUploadExceptionAdvice extends ResponseEntityExceptionHandler {   @ExceptionHandler(MaxUploadSizeExceededException.class)   public ResponseEntity<ResponseMessage> handleMaxSizeException(MaxUploadSizeExceededException exc) {     return ResponseEntity.status(HttpStatus.EXPECTATION_FAILED).body(new ResponseMessage("File too large!"));   } }                  

Initialize Storage

We need to run init() method of FilesStorageService (and also deleteAll() if necessary). So open SpringBootUploadFilesApplication.java and implement CommandLineRunner for run() method like this:

          package com.bezkoder.spring.files.upload; import javax.annotation.Resource; import org.springframework.boot.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import com.bezkoder.spring.files.upload.service.FilesStorageService; @SpringBootApplication public class SpringBootUploadFilesApplication implements CommandLineRunner {   @Resource   FilesStorageService storageService;   public static void main(String[] args) {     SpringApplication.run(SpringBootUploadFilesApplication.class, args);   }   @Override   public void run(String... arg) throws Exception {     storageService.deleteAll();     storageService.init();   } }                  

Run & Test

Run Spring Boot application with command: mvn spring-boot:run.
Refresh the project directory and you will see uploads folder inside it.

Let's use Postman to make some requests.

– Upload some files:

– Upload a file with size larger than max file size (500KB):

– Check uploads folder:

– Retrieve list of Files' information:

– Now you can download any file from one of the paths above.
For example: http://localhost:8080/files/bezkoder.png.

Conclusion

Today we've learned how to create Spring Boot File Upload Rest Api Application to upload multipart files and get files' information with static folder via Restful API.

Following tutorials explain how to build Front-end Apps to work with our Spring Boot Server:
– Angular 8 Client / Angular 10 Client / Angular 11 Client / Angular 12
– Angular Material 12
– Vue Client / Vuetify Client
– React Client / React Hooks Client
– Material UI Client
– React Image Upload with Preview
– Axios Client

For multiple Files at once:
How to upload multiple files in Java Spring Boot

You can also know way to upload an Excel/CSV file and store the content in MySQL database with the post:
– Spring Boot: Upload/Import Excel file data into MySQL Database
– Spring Boot: Upload/Import CSV file data into MySQL Database

If you want to store files in database like this:

You can find instruction at:
Spring Boot Upload/Download File to/from Database example

Happy Learning! See you again.

Further Reading

• Multipart Content-Type

Source Code

You can find the complete source code for this tutorial on Github.

phillipsmorave1997.blogspot.com

Source: https://www.bezkoder.com/spring-boot-file-upload/

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