React File Upload/Download example with Spring Boot Rest Api

In this tutorial, I will show you way to build React.js File Upload example with Spring Boot Rest APIs. The React App uses Axios and Multipart File for making HTTP requests, Bootstrap for progress bar. You also have a display list of files’ information (with download url).

More Fullstack Practice:
– React + Spring Boot: Pagination example
– Spring Boot + React: CRUD example
– Spring Boot + React: JWT Authentication with Spring Security

Run both projects in one place:
How to integrate React.js with Spring Boot

Using Template Engine:
Thymeleaf + Spring Boot: File Upload example

Overview

We’re gonna create a React File upload application in that user can:

• see the upload process (percentage) with progress bar
• view all uploaded files
• link to download the file when clicking on the file name

All uploaded files will be saved in uploads folder:

Technology

• React 16/17/18
• Axios 0.19.2
• Bootstrap 4
• Java 8
• Spring Boot 2 (with Spring Web MVC)
• Maven 3.6.1

Spring Boot Rest APIs for File Upload & Download

Here are APIs that Spring Boot server provides:

This is the project structure:

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

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

React App for upload/download Files

After building the React project is done, the folder structure will look like this:

Let me explain it briefly.

– upload-files.service provides methods to save File and get Files using Axios.
– upload-files.component contains upload form, progress bar, display of list files with download url.
– App.js is the container that we embed all React components.

– http-common.js initializes Axios with HTTP base Url and headers.
– We configure port for our App in .env

Setup React File Upload Project

Open cmd at the folder you want to save Project folder, run command:
npx create-react-app react-file-upload

After the process is done. We create additional folders and files like the following tree:

---

public
src
components
upload-files.component.js
services
upload-files.service.js
App.css
App.js
index.js
package.json

Import Bootstrap to React File Upload App

Run command: npm install bootstrap.

Open src/App.js and modify the code inside it as following-

import React, { Component } from "react";
import "bootstrap/dist/css/bootstrap.min.css";

class App extends Component {
  render() {
    // ...
  }
}

export default App;

Initialize Axios for React HTTP Client

Let’s install axios with command: npm install axios.
Under src folder, we create http-common.js file with following code:

import axios from "axios";

export default axios.create({
  baseURL: "http://localhost:8080",
  headers: {
    "Content-type": "application/json"
  }
});

You can change the baseURL that depends on REST APIs url that your Server configures.

Create Service for File Upload

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

• upload(file): POST form data with a callback for tracking upload progress
• getFiles(): GET list of Files’ information

services/upload-files.service.js

import http from "../http-common";

class UploadFilesService {
  upload(file, onUploadProgress) {
    let formData = new FormData();

    formData.append("file", file);

    return http.post("/upload", formData, {
      headers: {
        "Content-Type": "multipart/form-data",
      },
      onUploadProgress,
    });
  }

  getFiles() {
    return http.get("/files");
  }
}

export default new UploadFilesService();

– First we import Axios as http from http-common.js.

– Inside upload() method, we use FormData to store key-value pairs. It helps to build an object which corresponds to HTML form using append() method.

– We pass onUploadProgress to exposes progress events. This progress event are expensive (change detection for each event), so you should only use when you want to monitor it.

– We call Axios post() to send an HTTP POST for uploading a File to Rest APIs Server and get() method for HTTP GET request to retrieve all stored files.

Create Component for Upload Files

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

First we create a React component template and import UploadFilesService:

components/upload-files.component.js

import React, { Component } from "react";
import UploadService from "../services/upload-files.service";

export default class UploadFiles extends Component {
  constructor(props) {

  }

  render() {

  }
}

Then we define the state inside constructor() method:

export default class UploadFiles extends Component {
  constructor(props) {
    super(props);
    ...

    this.state = {
      selectedFiles: undefined,
      currentFile: undefined,
      progress: 0,
      message: "",

      fileInfos: [],
    };
  }
}

Next we define selectFile() method which helps us to get the selected Files from <input type="file" > element later.

export default class UploadFiles extends Component {
  ...
  selectFile(event) {
    this.setState({
      selectedFiles: event.target.files,
    });
  }

We use selectedFiles for accessing current File as the first Item. Then we call UploadService.upload() method on the currentFile with a callback. So create following upload() method:

export default class UploadFiles extends Component {
  ...
  upload() {
    let currentFile = this.state.selectedFiles[0];

    this.setState({
      progress: 0,
      currentFile: currentFile,
    });

    UploadService.upload(currentFile, (event) => {
      this.setState({
        progress: Math.round((100 * event.loaded) / event.total),
      });
    })
      .then((response) => {
        this.setState({
          message: response.data.message,
        });
        return UploadService.getFiles();
      })
      .then((files) => {
        this.setState({
          fileInfos: files.data,
        });
      })
      .catch(() => {
        this.setState({
          progress: 0,
          message: "Could not upload the file!",
          currentFile: undefined,
        });
      });

    this.setState({
      selectedFiles: undefined,
    });
  }

The progress will be calculated basing on event.loaded and event.total.
If the transmission is done, we call UploadService.getFiles() to get the files’ information and assign the result to fileInfos state, which is an array of {name, url} objects.

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

export default class UploadFiles extends Component {
  ...
  componentDidMount() {
    UploadService.getFiles().then((response) => {
      this.setState({
        fileInfos: response.data,
      });
    });
  }

Now we implement the render function of the Upload File UI. Add the following code inside render():

export default class UploadFiles extends Component {
  ...
  render() {
    const {
      selectedFiles,
      currentFile,
      progress,
      message,
      fileInfos,
    } = this.state;

    return (
      <div>
        {currentFile && (
          <div className="progress">
            <div
              className="progress-bar progress-bar-info progress-bar-striped"
              role="progressbar"
              aria-valuenow={progress}
              aria-valuemin="0"
              aria-valuemax="100"
              style={{ width: progress + "%" }}
            >
              {progress}%
            </div>
          </div>
        )}

        <label className="btn btn-default">
          <input type="file" onChange={this.selectFile} />
        </label>

        <button className="btn btn-success"
          disabled={!selectedFiles}
          onClick={this.upload}
        >
          Upload
        </button>

        <div className="alert alert-light" role="alert">
          {message}
        </div>

        <div className="card">
          <div className="card-header">List of Files</div>
          <ul className="list-group list-group-flush">
            {fileInfos &&
              fileInfos.map((file, index) => (
                <li className="list-group-item" key={index}>
                  <a href={file.url}>{file.name}</a>
                </li>
              ))}
          </ul>
        </div>
      </div>
    );
  }
}

In the code above, we use Bootstrap Progress Bar:

• .progress as a wrapper
• inner .progress-bar to indicate the progress
• .progress-bar requires style to set the width by percentage
• .progress-bar also requires role and some aria attributes to make it accessible
• label of the progress bar is the text within it

To display List of uploaded files, we iterate over fileInfos array using map() function. On each file item, we use file.url as href attribute and file.name for showing text.

Add File Upload Component to App Component

Open App.js, import and embed the UploadFiles Component tag.

import React from "react";
import "./App.css";
import "bootstrap/dist/css/bootstrap.min.css";

import UploadFiles from "./components/upload-files.component";

function App() {
  return (
    <div className="container" style={{ width: "600px" }}>
      <div style={{ margin: "20px" }}>
        <h3>bezkoder.com</h3>
        <h4>React upload Files</h4>
      </div>

      <UploadFiles />
    </div>
  );
}

export default App;

Configure Port for React File Upload App

Because most of HTTP Server use CORS configuration that accepts resource sharing retricted to some sites or ports, and if you use the Project in this post for making Server, you need to configure port for our App.

In project folder, create .env file with following content:

PORT=8081

So our app will run at port 8081.

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.

Run this React File Upload Axios: npm start.
Open Browser with url http://localhost:8081/ and check the result.

Further Reading

• https://github.com/axios/axios
• React Component
• Bootstrap 4 Progress
• React.js CRUD example to consume Web API
• React JWT Authentication (without Redux) example

Conclusion

Today we’re learned how to build an example for upload Files from React Client 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.

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

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

Similar React App using Hooks: React Hooks File Upload example with Axios & Progress Bar
Or Typescript: React Typescript File Upload example

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

You can find the instruction here:
React Multiple Files upload example with Progress Bar

Image Upload: React Image Upload with Preview

Or Material UI instead of Bootstrap:
Material UI File Upload example with Axios & Progress Bar

You will want to know how to run both projects in one place:
How to integrate React.js with Spring Boot

Using Template Engine:
Thymeleaf + Spring Boot: File Upload example

Source Code

The source code for the React Client is uploaded to Github.