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Step-by-step Guid: Google Authentication with Spring Boot

#springboot #oauth #google

Step-by-step Guid: Google Authentication with Spring Boot

1. Create a project

You can use Spring Initializr and select the following dependencies:

  • Spring Web
  • Spring Security
  • OAuth2 Client
  • Thymeleaf (optional, for testing UI)

Or you can add them in your pom.xml:

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-oauth2-client</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.thymeleaf.extras</groupId> <artifactId>thymeleaf-extras-springsecurity6</artifactId> </dependency>
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2. Create Google OAuth Credentials

Go to Google Cloud Console:

  1. Create a project.
  2. Navigate to "APIs & Service" > "Credentials"
  3. Click "Create Credentials" > "OAuth 2.0 Client IDs"
  4. Set:
    • Application type: "Web application"
    • Name: Your project name
    • Authorized redirect URIs: http://localhost:8080/login/oauth2/code/google Copy the Client ID and Client Secret.

3. Configure application.yml or application.properties

Using application.yml:

spring: security: oauth2: client: registration: google: client-id: YOUR_CLIENT_ID client-secret: YOUR_CLIENT_SECRET scope: - email - profile provider: google: authorization-uri: https://accounts.google.com/o/oauth2/v2/auth token-uri: https://oauth2.googleapis.com/token user-info-uri: https://www.googleapis.com/oauth2/v3/userinfo user-name-attribute: sub
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4. Create a Security Configuration

Spring Boot auto-configures basic OAuth login, but you can customize with security config:

// src/main/java/com.example.demo/SecurityConfig.java import org.springframework.context.annotation.Bean; import org.springframework.security.config.annotation.web.builders.HttpSecurity; import org.springframework.security.web.SecurityFilterChain; import org.springframework.context.annotation.Configuration; @Configuration public class SecurityConfig { @Bean public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception { http .authorizeHttpRequests(authorize -> authorize .requestMatchers("/", "/css/**", "/js/**").permitAll() .anyRequest().authenticated() ) .oauth2Login(); // Enables Google OAuth login return http.build(); } }
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5. Create a Simple Controller 

// src/main/java/com.example.demo/MainController.java import org.springframework.security.oauth2.client.authentication.OAuth2AuthenticationToken; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.GetMapping; @Controller public class MainController { @GetMapping("/") public String home() { return "home"; // a public page } @GetMapping("/dashboard") public String dashboard(Model model, OAuth2AuthenticationToken authentication) { Map<String, Object> attributes = authentication.getPrincipal().getAttributes(); model.addAttribute("name", attributes.get("name")); model.addAttribute("email", attributes.get("email")); return "dashboard"; // Secured page } }
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6. Create Template

Create the file at: src/main/resources/templates/home.html

<!-- home.html --> <!DOCTYPE html> <html xmlns:th="http://www.thymeleaf.org"> <head> <title>Home</title> </head> <body> <h1>Welcome to the public home page</h1> <a href="/dashboard">Go to Dashboard</a> </body> </html>
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Create the file at: src/main/resources/templates/dashboard.html

<!-- dashboard.html --> <!DOCTYPE html> <html xmlns:th="http://www.thymeleaf.org"> <head> <title>Dashboard</title> </head> <body> <h1>Welcome to the secure dashboard page</h1> <a href="/">Home</a> </body> </html>
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7. Run and Test

  1. Run your Spring Boot app.
  2. Navigate to http://localhost:8080/dashboard
  3. You'll be redirected to Google for login.
  4. After login, you'll return to /dashboard with your authenticated session.

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