// before
public class SecurityConfig extends WebSecurityConfigurerAdapter{	
...
          @Override
	  protected void configure(HttpSecurity http) throws Exception {
            ...
            .addFilter(new JwtAuthenticationFilter(authenticationManager()))
            ...
          }
}

// after
public class SecurityConfig {
...
          @Bean
	  SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
            ...
            .apply(new MyCustomDsl()) // 커스텀 필터 등록
            ...
          }

          public class MyCustomDsl extends AbstractHttpConfigurer<MyCustomDsl, HttpSecurity> {
		@Override
		public void configure(HttpSecurity http) throws Exception {
			AuthenticationManager authenticationManager = http.getSharedObject(AuthenticationManager.class);
			http
					.addFilter(corsConfig.corsFilter())
					.addFilter(new JwtAuthenticationFilter(authenticationManager))
					.addFilter(new JwtAuthorizationFilter(authenticationManager, userRepository));
		}
	}
}

// Object 를 String 으로 변환하여 반환
Object obj = session.getAttribute("user_name");
String user_name = obj.toString();

// String 자료형임을 명시
Object obj = session.getAttribute("user_name");
String user_name = (String)obj;

// UserEntity.java
@Entity
@Data
public class User {
    @Id // primary Key
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String username;
    private String password;
    private String email;
    private String role; // ROLE_USER, ROLE_ADMIN
    @CreationTimestamp
    private Timestamp crateDate;
}

// UserRepository.interface
public interface UserRepository extends JpaRepository<User, Integer> { // User 의 primaryKey 는 Integer

    // findBy 규칙, Username 문법
    // select * from user where username = ?
    public User findByUsername(String username);

    // findBy 규칙, Email 문법
    // select * from user where email = ?
    public User findByEmail(String email);
}

// Before 
@Override
public void configure(WebSecurity web){
 web.ignore().antMatchers("/assets/**", "/h2-console/**", "/api/hello2");
}

// After
@Bean
public WebSecurityCustomizer webSecurityCustomizer(){
 return (web) -> web.ignoring().antMatchers("/assets/**", "/h2-console/**", "/api/hello2");
}