Springboot - 자동 구성(Auto Configuration), @Conditional

@Data
public class Member {

    private String memberId;
    private String name;

    public Member() {
    }

    public Member(String memberId, String name) {
        this.memberId = memberId;
        this.name = name;
    }
}

@Repository
public class MemberRepository {

    private final JdbcTemplate template;

    public MemberRepository(JdbcTemplate template) {
        this.template = template;
    }

    public void initTable() {
        template.execute("create table member(member_id varchar primary key, name varchar)");
    }

    public void save(Member member) {
        template.update("insert into member(member_id, name) values (?,?)",
                member.getMemberId(),
                member.getName());
    }

    public Member find(String memberId) {
        return template.queryForObject("select member_id, name from member where member_id=?",
                BeanPropertyRowMapper.newInstance(Member.class),
                memberId);
    }

    public List<Member> findAll() {
        return template.query("select member_id, name from member",
                BeanPropertyRowMapper.newInstance(Member.class));
    }
}

@Slf4j
//@Configuration
public class DbConfig {

    @Bean
    public DataSource dataSource() {
        log.info("dataSource 빈 등록");
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setDriverClassName("org.h2.Driver");
        dataSource.setJdbcUrl("jdbc:h2:mem:test");
        dataSource.setUsername("sa");
        dataSource.setPassword("");
        return dataSource;
    }

    @Bean
    public TransactionManager transactionManager() {
        log.info("transactionManager 빈 등록");
        return new JdbcTransactionManager(dataSource());
    }

    @Bean
    public JdbcTemplate jdbcTemplate() {
        log.info("jdbcTemplate 빈 등록");
        return new JdbcTemplate(dataSource());
    }
}

@Slf4j
@SpringBootTest
class DbConfigTest {

    @Autowired
    DataSource dataSource;

    @Autowired
    TransactionManager transactionManager;

    @Autowired
    JdbcTemplate jdbcTemplate;

    @Test
    void checkBean() {
        log.info("dataSource = {}", dataSource);
        log.info("transactionManager = {}", transactionManager);
        log.info("jdbcTemplate = {}", jdbcTemplate);

        assertThat(dataSource).isNotNull();
        assertThat(transactionManager).isNotNull();
        assertThat(jdbcTemplate).isNotNull();
    }
}

- @Configuration을 주석 처리해 DataSource, TransactionManager, JdbcTemplate을 빈 등록하지 않았지만 테스트 코드에서는 정상 작동이 된다. 왜냐하면 스프링부트가 자동으로 이 3개를 등록해주기 때문이다.

 

 

package memory;

public class Memory {

    private long used;
    private long max;

    public Memory(long used, long max) {
        this.used = used;
        this.max = max;
    }

    public long getUsed() {
        return used;
    }

    public long getMax() {
        return max;
    }

    @Override
    public String toString() {
        return "Memory{" +
                "used=" + used +
                ", max=" + max +
                '}';
    }
}

package memory;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@Slf4j
@RestController
@RequiredArgsConstructor
public class MemoryController {

    private final MemoryFinder memoryFinder;

    @GetMapping("/memory")
    public Memory system() {
        Memory memory = memoryFinder.get();
        log.info("memory={}", memory);
        return memory;
    }
}

package memory;

import jakarta.annotation.PostConstruct;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class MemoryFinder {

    public Memory get() {
        long max = Runtime.getRuntime().maxMemory();
        long total = Runtime.getRuntime().totalMemory();
        long free = Runtime.getRuntime().freeMemory();
        long used = total - free;
        return new Memory(used, max);
    }

    @PostConstruct
    public void init() {
        log.info("init memoryFinder");
    }
}

package memory;

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;

@Slf4j
public class MemoryCondition implements Condition {
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        //-Dmemory=on
        String memory = context.getEnvironment().getProperty("memory");
        log.info("memory={}", memory);
        return "on".equals(memory);
    }
}

- MemoryCondition을 직접 구현했다. 

package hello.config;

import memory.MemoryCondition;
import memory.MemoryController;
import memory.MemoryFinder;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;

@Configuration
//@Conditional(MemoryCondition.class)
@ConditionalOnProperty(name = "memory", havingValue = "on")
public class MemoryConfig {

    @Bean
    public MemoryController memoryController() {
        return new MemoryController(memoryFinder());
    }

    @Bean
    public MemoryFinder memoryFinder() {
        return new MemoryFinder();
    }
}

Add VM options에서 -Dmemory=on 을 해준다.

@Configuration
@Conditional(MemoryCondition.class)
public class MemoryConfig {

    @Bean
    public MemoryController memoryController() {
        return new MemoryController(memoryFinder());
    }

    @Bean
    public MemoryFinder memoryFinder() {
        return new MemoryFinder();
    }
}

- @Conditional(MemoryCondition.class) 으로 MemoryConfig로 설정할 수 있게 해준다.

 

@Configuration
@ConditionalOnProperty(name = "memory", havingValue = "on")
public class MemoryConfig {

    @Bean
    public MemoryController memoryController() {
        return new MemoryController(memoryFinder());
    }

    @Bean
    public MemoryFinder memoryFinder() {
        return new MemoryFinder();
    }
}

- 직접 구현했지만 스프링부트는 이미 많은 conditional이 내재되어 있다. @ConditionalOnProperty(name = "memory", havingValue = "on")으로 MemoryConfig를 설정할 수 있게 해준다.

 

@ConditionalXxx

• @ConditionalOnClass , @ConditionalOnMissingClass - 클래스가 있는 경우 동작한다. 나머지는 그 반대
• @ConditionalOnBean , @ConditionalOnMissingBean - 빈이 등록되어 있는 경우 동작한다. 나머지는 그 반대
• @ConditionalOnProperty - 환경 정보가 있는 경우 동작한다.
• @ConditionalOnResource - 리소스가 있는 경우 동작한다.
• @ConditionalOnWebApplication , @ConditionalOnNotWebApplication - 웹 애플리케이션인 경우 동작한다.
• @ConditionalOnExpression - SpEL 표현식에 만족하는 경우 동작한다.