Java 子类化Java Builder类

你可以使用泛型来解决它。我认为这称为“好奇地重复通用模式”

将基类构建器方法的返回类型设为通用参数。

public class NutritionFacts {    private final int calories;    public static class Builder<T extends Builder<T>> {        private int calories = 0;        public Builder() {}        public T calories(int val) { calories = val; return (T) this;        }        public NutritionFacts build() { return new NutritionFacts(this); }    }    protected NutritionFacts(Builder<?> builder) {        calories = builder.calories;    }}

现在使用派生的类构建器作为通用参数实例化基本构建器。

public class GMOFacts extends NutritionFacts {    private final boolean hasGMO;    public static class Builder extends NutritionFacts.Builder<Builder> {        private boolean hasGMO = false;        public Builder() {}        public Builder GMO(boolean val) { hasGMO = val; return this;        }        public GMOFacts build() { return new GMOFacts(this); }    }    protected GMOFacts(Builder builder) {        super(builder);        hasGMO = builder.hasGMO;    }}