前提

由于 Spring 最新的 OAuth2 解决方案 已经由 Spring Security 下的 OAuth2 模块独立出来搞了个新的框架，之前的已经不维护了。
最近没事，翻翻官网看看。

依赖版本问题

确定Spring Boot 版本

我们观察Spring Boot 目前已经推出了 Spring Boot3 ，这个版本更新蛮大的，JDK 最低17。介于目前国内绝大部分应用运行在 JDK11 甚至 JDK8 下，因此可以选择 SpringBoot2 的最后一个版本，即 2.7.12

确定 Spring Authorization Server 版本

可能是由于框架刚独立出来的原因，这个库的版本目前并没有整合到Spring Boot 下。需要单独维护版本。因此就可能存在版本冲突问题
可以看下这个库的版本

可以看到版本更新还是挺跳跃的。
确定了 Spring Boot 版本，就可以选择较新的 Spring Authorization Server 的GA 版本。
经过测试，从 1.0.0 开始，就需要 升级到 Spring Boot3 (Spring6)了

因此，我们选择 0.4.2

最终的依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.12</version>
    </parent>

    <groupId>top.kalpana</groupId>
    <artifactId>spring-security-authorization</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-oauth2-authorization-server</artifactId>
            <version>0.4.2</version>
        </dependency>
    </dependencies>
</project>

第一个 Spring Authorization Server Demo

直接扒拉官方例子跑起来再说，细节后面再说

@Configuration
public class SecurityConfig {

	@Bean 
	@Order(1)
	public SecurityFilterChain authorizationServerSecurityFilterChain(HttpSecurity http)
			throws Exception {
		OAuth2AuthorizationServerConfiguration.applyDefaultSecurity(http);
		http.getConfigurer(OAuth2AuthorizationServerConfigurer.class)
			.oidc(Customizer.withDefaults());	// Enable OpenID Connect 1.0
		http
			// Redirect to the login page when not authenticated from the
			// authorization endpoint
			.exceptionHandling((exceptions) -> exceptions
				.authenticationEntryPoint(
					new LoginUrlAuthenticationEntryPoint("/login"))
			)
			// Accept access tokens for User Info and/or Client Registration
			.oauth2ResourceServer(OAuth2ResourceServerConfigurer::jwt);

		return http.build();
	}

	@Bean 
	@Order(2)
	public SecurityFilterChain defaultSecurityFilterChain(HttpSecurity http)
			throws Exception {
		http
			.authorizeHttpRequests((authorize) -> authorize
				.anyRequest().authenticated()
			)
			// Form login handles the redirect to the login page from the
			// authorization server filter chain
			.formLogin(Customizer.withDefaults());

		return http.build();
	}

	@Bean 
	public UserDetailsService userDetailsService() {
		UserDetails userDetails = User.withDefaultPasswordEncoder()
				.username("user")
				.password("password")
				.roles("USER")
				.build();

		return new InMemoryUserDetailsManager(userDetails);
	}

	@Bean 
	public RegisteredClientRepository registeredClientRepository() {
		RegisteredClient registeredClient = RegisteredClient.withId(UUID.randomUUID().toString())
				.clientId("messaging-client")
				.clientSecret("{noop}secret")
				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_BASIC)
				.authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
				.authorizationGrantType(AuthorizationGrantType.REFRESH_TOKEN)
				.authorizationGrantType(AuthorizationGrantType.CLIENT_CREDENTIALS)
				.redirectUri("http://127.0.0.1:8080/login/oauth2/code/messaging-client-oidc")
				.redirectUri("http://127.0.0.1:8080/authorized")
				.scope(OidcScopes.OPENID)
				.scope(OidcScopes.PROFILE)
				.scope("message.read")
				.scope("message.write")
				.clientSettings(ClientSettings.builder().requireAuthorizationConsent(true).build())
				.build();

		return new InMemoryRegisteredClientRepository(registeredClient);
	}

	@Bean 
	public JWKSource<SecurityContext> jwkSource() {
		KeyPair keyPair = generateRsaKey();
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		RSAKey rsaKey = new RSAKey.Builder(publicKey)
				.privateKey(privateKey)
				.keyID(UUID.randomUUID().toString())
				.build();
		JWKSet jwkSet = new JWKSet(rsaKey);
		return new ImmutableJWKSet<>(jwkSet);
	}

	private static KeyPair generateRsaKey() { 
		KeyPair keyPair;
		try {
			KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
			keyPairGenerator.initialize(2048);
			keyPair = keyPairGenerator.generateKeyPair();
		}
		catch (Exception ex) {
			throw new IllegalStateException(ex);
		}
		return keyPair;
	}

	@Bean 
	public JwtDecoder jwtDecoder(JWKSource<SecurityContext> jwkSource) {
		return OAuth2AuthorizationServerConfiguration.jwtDecoder(jwkSource);
	}

	@Bean 
	public AuthorizationServerSettings authorizationServerSettings() {
		return AuthorizationServerSettings.builder().build();
	}

}

启动成功，完结。