[spring]多種類の依存関係注入(DI)方法

5934 ワード
di Spring Java OOP テキストリンク

  • インプラント作成者
  • 不変、主に必須依存関係に用いられる
  • final利用可能/コンパイルエラーの原因となる可能性がある
  • 생성자가 1개면 @Autowired 생략해도됨 
    • 
  @Component
public class OrderServiceImpl implements OrderService {
 	private final MemberRepository memberRepository;
   	private final DiscountPolicy discountPolicy;
   
   @Autowired
   public OrderServiceImpl(MemberRepository memberRepository, DiscountPolicy 
  discountPolicy) {
     this.memberRepository = memberRepository;
     this.discountPolicy = discountPolicy;
   }
}

  • 注入モディファイヤ(setter)
  • 選択・変更可能な依存関係
     @Component
public class OrderServiceImpl implements OrderService {
  private MemberRepository memberRepository;
  private DiscountPolicy discountPolicy;
  @Autowired
  public void setMemberRepository(MemberRepository memberRepository) {
  	this.memberRepository = memberRepository;
  }
  @Autowired
  public void setDiscountPolicy(DiscountPolicy discountPolicy) {
  	this.discountPolicy = discountPolicy;
  }
}
    • 

- 필드 주입

  - 외부에서 변경이 불가능해서 테스트가 힘듦
  - 테스트목적의 특별한 용도에서 사용(코드가 짧음)
  - DI 프레임워크가 없으면 아무것도 안됨
  - 사용 비추천

```java
@Component
public class OrderServiceImpl implements OrderService {
   @Autowired
   private MemberRepository memberRepository;
   @Autowired
   private DiscountPolicy discountPolicy;
}

  • 従来のメソッド注入
  • 複数フィールドを一度に注入
    • Component
public class OrderServiceImpl implements OrderService {
   private MemberRepository memberRepository;
   private DiscountPolicy discountPolicy;
 @Autowired
 
 public void init(MemberRepository memberRepository, DiscountPolicy 
discountPolicy) {
   this.memberRepository = memberRepository;
   this.discountPolicy = discountPolicy;
 }
}
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