How to Implement JWT Authentication in AngularJS with a Java Spring REST API

What are the steps to implement JWT authentication using AngularJS for a Java Spring REST API?

Implementing JWT (JSON Web Token) authentication allows your AngularJS application to securely communicate with a Java Spring REST API. This guide provides a comprehensive step-by-step approach to achieve this, focusing on generating the token, authenticating requests, and securing API endpoints.

// AngularJS service for handling authentication
angular.module('app').service('AuthService', function($http, $window) {
    this.login = function(credentials) {
        return $http.post('/api/auth/login', credentials)
            .then(function(response) {
                $window.localStorage.setItem('jwt', response.data.token);
            });
    };  
    this.getToken = function() {
        return $window.localStorage.getItem('jwt');
    };
    this.isAuthenticated = function() {
        return !!this.getToken();
    };
});

Causes

• AngularJS applications lack built-in authentication mechanisms.
• REST APIs require secure communication protocols to prevent unauthorized access.

Solutions

• Set up Spring Security in your Java backend to manage JWT verification.
• Create an authentication service in AngularJS to handle login requests and store the received JWT.
• Secure your REST API endpoints by requiring JWT tokens in the headers of requests.

Mistake: Not sending the JWT token in the authorization header.

Solution: Ensure that every API request includes the token in the headers as follows: { headers: { Authorization: 'Bearer ' + token }}.

Mistake: Missing JWT expiration validation.

Solution: Always validate the expiration of the JWT token on both the client and server side.