Angular 13 + Spring Boot: File upload/download example

In this tutorial, I will show you way to build Angular 13 File upload & download example with Spring Boot server.

More Practice:
– Thymeleaf + Spring Boot: File Upload example
– Angular + Spring Boot: CRUD example
– Angular + Spring Boot: JWT Authentication example
– Angular + Spring Boot: Pagination example

For Multiple Files Upload at once:
Angular 13 Multiple Files upload example with Progress Bar

Serverless with Firebase:
Angular 13 File Upload with Firebase Storage example

Other versions:
– Angular 8 + Spring Boot: File upload example
– Angular 10 + Spring Boot: File upload example
– Angular 11 + Spring Boot: File upload example
– Angular 12 + Spring Boot: File upload example
– Angular 14 + Spring Boot: File upload example
– Angular 15 + Spring Boot: File upload example
– Angular 16 + Spring Boot: File upload example

With Angular Material:
Angular Material File upload example

Contents

Overview
Angular 13 + Spring Boot File upload Architecture
Technology
Spring Boot Rest APIs for File Upload & Storage
Angular 13 Client for file upload/download UI
Angular 13 Project Structure
Set up App Module for HttpClient
Add Bootstrap to the project
Create Angular 13 Service for Upload Files
Create Component for Upload Files
Add Upload File Component to App Component
Run the App
Further Reading
Conclusion

Overview

We’re gonna create a full-stack Angular 13 File upload to Spring Boot Server in that user can:

see the upload process (percentage)
view all uploaded files
download by clicking on the file name

All uploaded files will be saved in uploads folder:

Angular 13 + Spring Boot File upload Architecture

Let’s look at the architecture below:

Angular 13 Client:

FileUpload Component calls UploadService functions for upload/download/display files
UploadService uses HttpClientModule to make HTTP requests

Spring Boot Server:

FilesController receives the HTTP requests from Client, then calls FilesStorageService functions for upload/download/getting files
FilesStorageService implements functions for storing and retrieving file systems using Java Files library

Technology

Server:

Java 17 / 11 / 8
Spring Boot 3 / 2 (with Spring Web MVC)
Maven

Client:

Angular 13
RxJS 7
Bootstrap 4

Spring Boot Rest APIs for File Upload & Storage

Spring Boot App will provide APIs:

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 project structure:

– 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.
– pom.xml for Spring Boot dependency.

You can find Step by Step to implement the Spring Boot Server (with Github) at:
Spring Boot Multipart File upload (to static folder) example

Or: Spring Boot Multipart File upload (to database) example

Angular 13 Client for file upload/download UI

Let’s open cmd and use Angular CLI to create a new Angular 13 Project as following command:

ng new Angular13FileUpload
? Would you like to add Angular routing? No
? Which stylesheet format would you like to use? CSS

We also need to generate some Components and Services:

ng g s services/file-upload
ng g c components/file-upload

Now you can see that our project directory structure looks like this.

Angular 13 Project Structure

Let me explain it briefly.

– We import necessary library, components in app.module.ts.
– file-upload.service provides methods to save File and get Files from Rest API Server using HttpClient.
– file-upload.component contains upload form, progress bar, display of list files.
– app.component is the container that we embed all components.
– index.html for importing the Bootstrap.

Set up App Module for HttpClient

Open app.module.ts and import HttpClientModule:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http';

import { AppComponent } from './app.component';
import { FileUploadComponent } from './components/file-upload/file-upload.component';

@NgModule({
  declarations: [
    AppComponent,
    FileUploadComponent
  ],
  imports: [
    BrowserModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Add Bootstrap to the project

Open index.html and add following line into <head> tag:

<!DOCTYPE html>
<html lang="en">
  <head>
    ...
    <link rel="stylesheet" href="https://unpkg.com/[email protected]/dist/css/bootstrap.min.css" />
  </head>
  ...
</html>

Create Angular 13 Service for Upload Files

This service will use Angular HttpClient to send HTTP requests.
There are 2 functions:

upload(file): returns Observable<HttpEvent<any>> that we’re gonna use for tracking progress
getFiles(): returns a list of Files’ information as Observable object

services/file-upload.service.ts

import { Injectable } from '@angular/core';
import { HttpClient, HttpRequest, HttpEvent } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class FileUploadService {
  private baseUrl = 'http://localhost:8080';

  constructor(private http: HttpClient) { }

  upload(file: File): Observable<HttpEvent<any>> {
    const formData: FormData = new FormData();

    formData.append('file', file);

    const req = new HttpRequest('POST', `${this.baseUrl}/upload`, formData, {
      reportProgress: true,
      responseType: 'json'
    });

    return this.http.request(req);
  }

  getFiles(): Observable<any> {
    return this.http.get(`${this.baseUrl}/files`);
  }
}

– FormData is a data structure that can be used to store key-value pairs. We use it to build an object which corresponds to an HTML form with append() method.

– We set reportProgress: true to exposes progress events. Notice that this progress event are expensive (change detection for each event), so you should only use when you want to monitor it.

– We call the request(PostRequest) & get() method of HttpClient to send an HTTP POST & Get request to the Spring Boot File Upload server.

Create Component for Upload Files

Let’s create a File Upload UI with Progress Bar, Card, Button and Message.

First we need to use the following imports:

file-upload.component.ts

import { Component, OnInit } from '@angular/core';
import { HttpEventType, HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs';
import { FileUploadService } from 'src/app/services/file-upload.service';

Then we define the some variables and inject FileUploadService as follows:

export class FileUploadComponent implements OnInit {

  selectedFiles?: FileList;
  currentFile?: File;
  progress = 0;
  message = '';

  fileInfos?: Observable<any>;

  constructor(private uploadService: FileUploadService) { }

}

Next we define selectFile() method. It helps us to get the selected Files.

selectFile(event: any): void {
  this.selectedFiles = event.target.files;
}

Next we write upload() method for upload file:

export class FileUploadComponent implements OnInit {
  selectedFiles?: FileList;
  currentFile?: File;
  progress = 0;
  message = '';

  fileInfos?: Observable<any>;

  constructor(private uploadService: FileUploadService) { }

  selectFile(event: any): void {
    this.selectedFiles = event.target.files;
  }

  upload(): void {
    this.progress = 0;

    if (this.selectedFiles) {
      const file: File | null = this.selectedFiles.item(0);

      if (file) {
        this.currentFile = file;

        this.uploadService.upload(this.currentFile).subscribe({
          next: (event: any) => {
            if (event.type === HttpEventType.UploadProgress) {
              this.progress = Math.round(100 * event.loaded / event.total);
            } else if (event instanceof HttpResponse) {
              this.message = event.body.message;
              this.fileInfos = this.uploadService.getFiles();
            }
          },
          error: (err: any) => {
            console.log(err);
            this.progress = 0;

            if (err.error && err.error.message) {
              this.message = err.error.message;
            } else {
              this.message = 'Could not upload the file!';
            }

            this.currentFile = undefined;
          }
        });
      }

      this.selectedFiles = undefined;
    }
  }

}

We use selectedFiles for accessing current File as the first Item. Then we call uploadService.upload() method on the currentFile.

The progress will be calculated basing on event.loaded and event.total.
If the transmission is done, the event will be a HttpResponse object. At this time, we call uploadService.getFiles() to get the files’ information and assign the result to fileInfos variable.

We also need to do this work in ngOnInit() method:

ngOnInit(): void {
  this.fileInfos = this.uploadService.getFiles();
}

Now we create the HTML template of the Upload File UI. Add the following content to file-upload.component.html file:

<div class="row">
  <div class="col-8">
    <label class="btn btn-default p-0">
      <input type="file" (change)="selectFile($event)" />
    </label>
  </div>

  <div class="col-4">
    <button class="btn btn-success btn-sm" [disabled]="!selectedFiles" (click)="upload()">
      Upload
    </button>
  </div>
</div>

<div *ngIf="currentFile" class="progress my-3">
  <div
    class="progress-bar progress-bar-info progress-bar-striped"
    role="progressbar"
    attr.aria-valuenow="{{ progress }}"
    aria-valuemin="0"
    aria-valuemax="100"
    [ngStyle]="{ width: progress + '%' }"
  >
    {{ progress }}%
  </div>
</div>

<div *ngIf="message" class="alert alert-secondary" role="alert">{{ message }}</div>

<div class="card mt-3">
  <div class="card-header">List of Files</div>
  <ul
    class="list-group list-group-flush"
    *ngFor="let file of fileInfos | async"
  >
    <li class="list-group-item">
      <a href="{{ file.url }}">{{ file.name }}</a>
    </li>
  </ul>
</div>

Add Upload File Component to App Component

Open app.component.html and embed the FileUpload Component with <app-file-upload> tag.

<div class="container" style="width:600px">
  <div class="my-3">
    <h3>bezkoder.com</h3>
    <h4>{{ title }}</h4>
  </div>

  <app-file-upload></app-file-upload>
</div>

app.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Angular 13 File Upload';
}

Run the App

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

Because we configure CORS for origin: http://localhost:8081, so you need to run Angular 13 Client with command:
ng serve --port 8081

Open Browser with url http://localhost:8081/ and check the result.

Conclusion

Today we’re learned how to build an example for upload Files from Angular 13 to Spring Boot server. We also provide the ability to show list of files, upload progress using Bootstrap, and to download file from the server.

Next tutorials will show you way to implement the full-stack (with source code):
– Back-end: File Upload to Static folder / File Upload to Database
– Front-end

If you want to upload multiple files at once like this:

You can find the instruction (with Github) here:
Angular 13 Multiple Files upload example with Progress Bar

Or use Angular Material like this:

Angular Material File upload example

You will want to know how to run both projects in one place:
How to Integrate Angular with Spring Boot Rest API

Happy Learning! See you again.