Spring Boot Upload/Download File to/from Database example

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

This Spring Boot App works with:
– Angular Client
– Vue Client / Vuetify Client
– React Client / React Hooks 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 to Database

Our Spring Boot Application will provide APIs for:

• uploading File to PostgreSQL/MySQL database
• downloading File database with the link
• getting list of Files’ information (file name, url, type, size)

These are APIs to be exported:

The uploaded files will be stored in PostgreSQL/MySQL Database files table with these fields: id, name, type and data as BLOB type (Binary Large Object is for storing binary data like file, image, audio, or video).

Technology

• Java 8
• Spring Boot 2 (with Spring Web MVC)
• PostgreSQL/MySQL Database
• Maven 3.6.1

Project Structure

Let me explain it briefly.

– FileDB is the data model corresponding to files table in database.
– FileDBRepository extends Spring Data JpaRepository which has methods to store and retrieve files.
– FilesStorageService uses FileDBRepository to provide methods for saving new file, get file by id, get list of 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.
– ResponseFile contains information of the file (name, url, type, size) for HTTP response payload.
– application.properties contains configuration for Servlet Multipart and PostgreSQL/MySQL database connection.
– pom.xml for Spring Boot, Spring Data JPA and PostgreSQL/MySQL connector 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>

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

We also need to add one more dependency.
– If you want to use MySQL:

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<scope>runtime</scope>
</dependency>

– or PostgreSQL:

<dependency>
	<groupId>org.postgresql</groupId>
	<artifactId>postgresql</artifactId>
	<scope>runtime</scope>
</dependency>

Create Data Model

This Data Model is for storing File Data. There are four fields:

• id: automatically generated as UUID
• name: name of the file
• type: mime type
• data: array of bytes, map to a BLOB

model/FileDB.java

package com.bezkoder.spring.files.upload.db.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Lob;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

@Entity
@Table(name = "files")
public class FileDB {
  @Id
  @GeneratedValue(generator = "uuid")
  @GenericGenerator(name = "uuid", strategy = "uuid2")
  private String id;

  private String name;

  private String type;

  @Lob
  private byte[] data;

  public FileDB() {
  }

  public FileDB(String name, String type, byte[] data) {
    this.name = name;
    this.type = type;
    this.data = data;
  }

  public String getId() {
    return id;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public String getType() {
    return type;
  }

  public void setType(String type) {
    this.type = type;
  }

  public byte[] getData() {
    return data;
  }

  public void setData(byte[] data) {
    this.data = data;
  }

}

In the code above, data is annotated by @Lob annotation. LOB is datatype for storing large object data. There’re two kinds of LOB: BLOB and CLOB:

• BLOB is for storing binary data
• CLOB is for storing text data

Create Repository

Under repository package, create FileDBRepository interface that extends JpaRepository.

repository/FileDBRepository.java

package com.bezkoder.spring.files.upload.db.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.bezkoder.spring.files.upload.db.model.FileDB;

@Repository
public interface FileDBRepository extends JpaRepository<FileDB, String> {

}

Now we can use FileDBRepository with JpaRepository‘s methods such as: save(FileDB), findById(id), findAll().

Create Service for File Storage

The File Storage Service will use FileDBRepository to provide following methods:

• store(file): receives MultipartFile object, transform to FileDB object and save it to Database
• getFile(id): returns a FileDB object by provided Id
• getAllFiles(): returns all stored files as list of code>FileDB objects

service/FileStorageService.java

package com.bezkoder.spring.files.upload.db.service;

import java.io.IOException;
import java.util.stream.Stream;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.StringUtils;
import org.springframework.web.multipart.MultipartFile;

import com.bezkoder.spring.files.upload.db.model.FileDB;
import com.bezkoder.spring.files.upload.db.repository.FileDBRepository;

@Service
public class FileStorageService {

  @Autowired
  private FileDBRepository fileDBRepository;

  public FileDB store(MultipartFile file) throws IOException {
    String fileName = StringUtils.cleanPath(file.getOriginalFilename());
    FileDB FileDB = new FileDB(fileName, file.getContentType(), file.getBytes());

    return fileDBRepository.save(FileDB);
  }

  public FileDB getFile(String id) {
    return fileDBRepository.findById(id).get();
  }
  
  public Stream<FileDB> getAllFiles() {
    return fileDBRepository.findAll().stream();
  }
}

Define Response Information Classes

Let’s create two classes in message package. The controller will use these classes for sending message via HTTP responses.

• ResponseFile: contains name, url, type, size
• ResponseMessage for notification/information message

message/ResponseFile.java

package com.bezkoder.spring.files.upload.db.message;

public class ResponseFile {
  private String name;
  private String url;
  private String type;
  private long size;

  public ResponseFile(String name, String url, String type, long size) {
    this.name = name;
    this.url = url;
    this.type = type;
    this.size = size;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public String getUrl() {
    return url;
  }

  public void setUrl(String url) {
    this.url = url;
  }

  public String getType() {
    return type;
  }

  public void setType(String type) {
    this.type = type;
  }

  public long getSize() {
    return size;
  }

  public void setSize(long size) {
    this.size = size;
  }
}

message/ResponseMessage.java

package com.bezkoder.spring.files.upload.db.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 to Database

In controller package, we create FileController class.

controller/FileController.java

package com.bezkoder.spring.files.upload.db.controller;

import java.util.List;
import java.util.stream.Collectors;

import org.springframework.beans.factory.annotation.Autowired;
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.multipart.MultipartFile;
import org.springframework.web.servlet.support.ServletUriComponentsBuilder;

import com.bezkoder.spring.files.upload.db.service.FileStorageService;
import com.bezkoder.spring.files.upload.db.message.ResponseFile;
import com.bezkoder.spring.files.upload.db.message.ResponseMessage;
import com.bezkoder.spring.files.upload.db.model.FileDB;

@Controller
@CrossOrigin("http://localhost:8081")
public class FileController {

  @Autowired
  private FileStorageService storageService;

  @PostMapping("/upload")
  public ResponseEntity<ResponseMessage> uploadFile(@RequestParam("file") MultipartFile file) {
    String message = "";
    try {
      storageService.store(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<ResponseFile>> getListFiles() {
    List<ResponseFile> files = storageService.getAllFiles().map(dbFile -> {
      String fileDownloadUri = ServletUriComponentsBuilder
          .fromCurrentContextPath()
          .path("/files/")
          .path(dbFile.getId())
          .toUriString();

      return new ResponseFile(
          dbFile.getName(),
          fileDownloadUri,
          dbFile.getType(),
          dbFile.getData().length);
    }).collect(Collectors.toList());

    return ResponseEntity.status(HttpStatus.OK).body(files);
  }

  @GetMapping("/files/{id}")
  public ResponseEntity<byte[]> getFile(@PathVariable String id) {
    FileDB fileDB = storageService.getFile(id);

    return ResponseEntity.ok()
        .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileDB.getName() + "\"")
        .body(fileDB.getData());
  }
}

– @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/[id]: getFile()

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

Configure Spring Datasource, JPA, Hibernate

Under src/main/resources folder, open application.properties and write these lines.

– For MySQL:

spring.datasource.url= jdbc:mysql://localhost:3306/testdb?useSSL=false
spring.datasource.username= root
spring.datasource.password= 123456

spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.MySQL5InnoDBDialect

# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto= update

– For PostgreSQL:

spring.datasource.url= jdbc:postgresql://localhost:5432/testdb
spring.datasource.username= postgres
spring.datasource.password= 123

spring.jpa.properties.hibernate.jdbc.lob.non_contextual_creation= true
spring.jpa.properties.hibernate.dialect= org.hibernate.dialect.PostgreSQLDialect

# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto= update

• spring.datasource.username & spring.datasource.password properties are the same as your database installation.
• Spring Boot uses Hibernate for JPA implementation, we configure MySQL5InnoDBDialect for MySQL or PostgreSQLDialect for PostgreSQL
• spring.jpa.hibernate.ddl-auto is used for database initialization. We set the value to update value so that a table will be created in the database automatically corresponding to defined data model. Any change to the model will also trigger an update to the table. For production, this property should be validate.

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=2MB
spring.servlet.multipart.max-request-size=2MB

– 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.db.exception;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.multipart.MaxUploadSizeExceededException;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

import com.bezkoder.spring.files.upload.db.message.ResponseMessage;

@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!"));
  }
}

Run & Test

Run Spring Boot application with command: mvn spring-boot:run.
Let’s use Postman to make some requests.

– Upload some files:

– Upload a file with size larger than max file size (2MB):

– Check files table in Database:

– Retrieve list of Files’ information:

– Now you can download any file from one of the paths above.
For example: http://localhost:8080/files/6ba3578c-ce22-4dd7-999e-72192bf31b53

Conclusion

Today we’ve learned how to create Spring Boot 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 10 Client
– Vue Client
– React Client

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

Happy Learning! See you again.

Further Reading

• Multipart Content-Type
• How to upload multiple files in Java Spring Boot

Source Code

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