Spring Boot：Oauth2：访问被拒绝（用户是匿名的）；重定向到身份验证入口点

使用Spring Boot进行身份验证是开发Web应用程序的常见需求。OAuth2是一种用于授权和身份验证的开放标准，它允许用户授权第三方应用程序访问其受保护的资源，而不需要共享其凭据。在本文中，我们将探讨如何使用Spring Boot和OAuth2进行身份验证，并解决访问被拒绝的问题。

yaml
spring:
  security:
    oauth2:
      client:
        registration:
          google:
            client-id: YOUR_CLIENT_ID
            client-secret: YOUR_CLIENT_SECRET
            redirect-uri: /login/oauth2/code/google
        provider:
          google:
            authorization-uri: https://accounts.google.com/o/oauth2/auth
            token-uri: https://accounts.google.com/o/oauth2/token
            user-info-uri: https://www.googleapis.com/oauth2/v3/userinfo
            user-name-attribute: sub

java
@Component
public class CustomAuthenticationEntryPoint implements AuthenticationEntryPoint {
    @Override
    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException {
        response.sendRedirect("/login");
    }
}

java
@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .antMatchers("/public/**").permitAll()
                .anyRequest().authenticated()
                .and()
                .oauth2Login()
                .and()
                .exceptionHandling()
                .authenticationEntryPoint(new CustomAuthenticationEntryPoint());
    }
}

java
@SpringBootApplication
public class OAuth2DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(OAuth2DemoApplication.class, args);
    }
}
@RestController
public class HelloController {
    @GetMapping("/")
    public String hello() {
        return "Hello, World!";
    }
    @GetMapping("/protected")
    public String protectedResource() {
        return "This is a protected resource.";
    }
}
@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .antMatchers("/public/**").permitAll()
                .anyRequest().authenticated()
                .and()
                .oauth2Login()
                .and()
                .exceptionHandling()
                .authenticationEntryPoint(new CustomAuthenticationEntryPoint());
    }
}
@Component
public class CustomAuthenticationEntryPoint implements AuthenticationEntryPoint {
    @Override
    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException {
        response.sendRedirect("/login");
    }
}