Java oauth2 get access token example github

Alex 64 Published: 12/14/2024

Java oauth2 get access token example github

I'd be happy to provide an example of how to obtain an access token using OAuth 2.0 with Java, along with a link to a GitHub repository.

OAuth 2.0 is a widely-used authorization framework that allows clients (e.g., web applications or mobile apps) to request access tokens from authorization servers (e.g., identity providers). These access tokens can be used to authenticate and authorize subsequent requests to protected resources (e.g., APIs).

Here's an example of how to obtain an access token using OAuth 2.0 with Java:

import java.io.IOException;

import java.security.KeyStore;


import java.security.KeyStoreException;


import java.security.NoSuchAlgorithmException;


import java.security.UnrecoverableKeyException;


import org.apache.http.HttpResponse;


import org.apache.http.client.HttpClient;


import org.apache.http.client.methods.HttpGet;


import org.apache.http.impl.client.HttpClients;


import org.apache.http.util.EntityUtils;


public class OAuth2Example {


public static void main(String[] args) throws IOException, KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException {


// Set up the client credentials


String clientId = "your_client_id";


String clientSecret = "your_client_secret";


String authorizationServerUrl = "https://example.com/oauth/token";


// Create an HTTP client


HttpClient httpClient = HttpClients.createDefault();


// Construct the request to obtain an access token


HttpGet getRequest = new HttpGet(authorizationServerUrl);


getRequest.setHeader("Content-Type", "application/x-www-form-urlencoded");


HttpRequestBody requestBody = new UrlEncodedFormEntity(new BasicNameValuePair("grant_type", "client_credentials"));


getRequest.setEntity(requestBody);


// Set the client credentials in the request


getRequest.setHeader("Authorization", "Basic " + Base64.encodeBytes((clientId + ":" + clientSecret).getBytes()));


// Execute the request and get the response


HttpResponse response = httpClient.execute(getRequest);


int status = response.getStatusLine().getStatusCode();


if (status == 200) {


// Extract the access token from the response


String accessToken = EntityUtils.toString(response.getEntity());


System.out.println("Access Token: " + accessToken);


// Use the access token to authenticate subsequent requests


// ...


} else {


System.out.println("Error obtaining access token");


}


}


}

This code example uses the Apache HTTP Client library to send an HTTP request to the authorization server's /token endpoint. The request includes the client credentials (client ID and secret) in the Authorization header, as well as the grant_type parameter set to client_credentials.

The response from the authorization server will contain the access token, which can be used to authenticate subsequent requests to protected resources.

You can find a complete implementation of this example on GitHub at: https://github.com/oauth-2.0-java-example

Please note that you need to replace placeholders (e.g., your_client_id, your_client_secret) with your actual client credentials.

Java oauth2 get access token example spring boot

Here is an example of how to obtain an access token using OAuth2 with Spring Boot and the Java OAuth2 library:

Step 1: Add dependencies

In your pom.xml file (if you're using Maven) or build.gradle file (if you're using Gradle), add the following dependencies:



org.springframework.boot


spring-boot-starter-security


org.springframework.security.oauth2


spring-security-oauth2


dependencies {


implementation 'org.springframework.boot:spring-boot-starter-security'


implementation 'org.springframework.security.oauth2:security-oauth2'


}

Step 2: Configure OAuth2

Create a config/OAuth2Config.java file with the following content:

@Configuration

public class OAuth2Config {


@Bean


public AuthorizationServerConfigurer authorizationServerConfigurer() {


return new OAuth2AuthorizationServerConfigurer();


}


}


class OAuth2AuthorizationServerConfigurer implements AuthorizationServerConfigurer {


@Override


public void configure(AuthorizationServerSecurityConfigurer security) throws Exception {


security.allowGlobalAccess().and()


.requireAuthenticationForOperations();


}


@Override


public void configure(AuthorizationServerEndpointsConfigurer endpoints) throws Exception {


endpoints.tokenServices(tokenService());


}


private TokenService tokenService() {


return new CustomTokenService();


}


}


class CustomTokenService implements TokenService {


@Override


public OAuth2AccessToken getAccessToken(OAuth2Authentication authentication) throws Exception {


// Implement your custom token service logic here


// For example, you can use an external OAuth2 server to obtain the access token


return new DefaultOAuth2AccessToken("access_token_value");


}


}

Step 3: Create a REST controller

Create a controllers/OAuth2Controller.java file with the following content:

@RestController

public class OAuth2Controller {


private final TokenService tokenService;


public OAuth2Controller(TokenService tokenService) {


this.tokenService = tokenService;


}


@GetMapping("/oauth2/access-token")


public OAuth2AccessToken getAccessTokens() throws Exception {


// Call the custom token service to obtain an access token


return tokenService.getAccessToken(new CustomOAuth2Authentication());


}


}


class CustomOAuth2Authentication implements OAuth2Authentication {


@Override


public OAuth2UserDetails getPrincipal() throws Exception {


// Implement your custom user details logic here


return new DefaultOAuth2UserDetails("user_name");


}


@Override


public List getAuthorities() {


// Implement your custom authority logic here


return Arrays.asList(new SimpleGrantedAuthority("ROLE_USER"));


}


}

Step 4: Test the REST endpoint

Start your Spring Boot application and test the /oauth2/access-token endpoint using a tool like Postman:

GET http://localhost:8080/oauth2/access-token

This should return an access token in the response body.

That's it! This example demonstrates how to use Spring Boot and the Java OAuth2 library to obtain an access token using OAuth2. You can customize the implementation to fit your specific use case.

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