빌더패턴은 쓰레드 세이프 한가요?

Question

public class NutritionFacts { private final int servingSize; private final int servings; private final int calories; private final int fat; private final int sodium; private final int carbohydrate; public static class Builder { // Required parameters private final int servingSize; private final int servings; // Optional parameters - initialized to default values private int calories &#61; 0; private int fat &#61; 0; private int carbohydrate &#61; 0; private int sodium &#61; 0; public Builder(int servingSize, int servings) { this.servingSize &#61; servingSize; this.servings &#61; servings; } public Builder calories(int val) { calories &#61; val; return this; } public Builder fat(int val) { fat &#61; val; return this; } public Builder carbohydrate(int val) { carbohydrate &#61; val; return this; } public Builder sodium(int val) { sodium &#61; val; return this; } public NutritionFacts build() { return new NutritionFacts(this); } } private NutritionFacts(Builder builder) { servingSize &#61; builder.servingSize; servings &#61; builder.servings; calories &#61; builder.calories; } } 이렇게 빌더패턴이 있을 때 서블릿 같은 멀티쓰레드 환경에서과연 쓰레드 세이프 한가요? 이너클래스인 Builder 클래스가 static으로 선언 되어있고그 안에 멤버변수들을 가지고 NutritionFacts 클래스를 생성하고 있어서 쓰레드 세이프 하진 않을거 같은데요... 답변 부탁 드립니다.

antop · Answer

네

김룰룰룰 · Answer

Builder는 사용할 때마다 instance를 새로 생성해야 합니다. instance를 매번 새로 생성하므로 공유하지 않는 이상 thread unsafe하진 않습니다.빌더 예제public class NutritionFacts { private final int servingSize; private final int servings; private final int calories; private final int fat; private final int sodium; private final int carbohydrate; public static class Builder { private final int servingSize; private final int servings; private int calories &#61; 0; private int fat &#61; 0; private int carbohydrate &#61; 0; private int sodium &#61; 0; public Builder(int servingSize, int servings) { this.servingSize &#61; servingSize; this.servings &#61; servings; } public Builder calories(int val) { calories &#61; val; return this; } public Builder fat(int val) { fat &#61; val; return this; } public Builder carbohydrate(int val) { carbohydrate &#61; val; return this; } public Builder sodium(int val) { sodium &#61; val; return this; } public NutritionFacts build() { return new NutritionFacts(this); } } private NutritionFacts(Builder builder) { servingSize &#61; builder.servingSize; servings &#61; builder.servings; calories &#61; builder.calories; fat &#61; builder.fat; sodium &#61; builder.sodium; carbohydrate &#61; builder.carbohydrate; } }사용 예제NutritionFacts cocaCola &#61; new NutritionFacts .Builder(240, 8) // 빌더의 인스턴스 생성 (생성자) .calories(100) .sodium(35) .carbohydrate(27) .build();코드 출처: https://johngrib.github.io/wiki/builder-pattern/

빌더패턴은 쓰레드 세이프 한가요?

2개의 답변

#builder 목록