你還在 new 對象嗎？Java8 通用 Builder 了解一下？

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來自：rrd.me/gtQTp

public class GirlFriend {
  private String name;
  private int age;
  // 省略 getter & setter ...
  public static void main(String[] args) {
    GirlFriend myGirlFriend = new GirlFriend();
    myGirlFriend.setName("小美");
    myGirlFriend.setAge(18);
  }
}

public class GirlFriend {
  private String name;
  private int age;
  private int bust;
  private int waist;
  private int hips;
  private Listhobby;
  private String birthday;
  private String address;
  private String mobile;
  private String email;
  private String hairColor;
  private Mapgift;
  // 等等等等 ...
  // 省略 getter & setter ...
  public static void main(String[] args) {
    GirlFriend myGirlFriend = new GirlFriend();
    myGirlFriend.setName("小美");
    myGirlFriend.setAge(18);
    myGirlFriend.setBust(33);
    myGirlFriend.setWaist(23);
    myGirlFriend.setHips(33);
    myGirlFriend.setBirthday("2001-10-26");
    myGirlFriend.setAddress("上海浦東");
    myGirlFriend.setMobile("18688888888");
    myGirlFriend.setEmail("[email protected]");
    myGirlFriend.setHairColor("淺棕色帶點(diǎn)微卷");
    Listhobby = new ArrayList<>();
    hobby.add("逛街");
    hobby.add("購物");
    hobby.add("買東西");
    myGirlFriend.setHobby(hobby);
    Mapgift = new HashMap<>();
    gift.put("情人節(jié)禮物", "LBR 1912女王時(shí)代");
    gift.put("生日禮物", "迪奧烈焰藍(lán)金");
    gift.put("紀(jì)念日禮物", "阿瑪尼紅管唇釉");
    myGirlFriend.setGift(gift);
    // 等等等等 ...
  }
}

GirlFriend{name='小美'
, age=18
, bust=33
, waist=23
, hips=33
, hobby=[逛街, 購物, 買東西]
, birthday='2001-10-26'
, address='上海浦東'
, mobile='18688888888'
, email='[email protected]'
, hairColor='淺棕色帶點(diǎn)微卷'
, gift={情人節(jié)禮物=LBR 1912女王時(shí)代, 生日禮物=迪奧烈焰藍(lán)金, 紀(jì)念日禮物=阿瑪尼紅管唇釉}
}

public class GirlFriend {
// 省略屬性 ...
// 省略 getter & setter ...

// 為了演示方便，加幾個(gè)聚合方法
public void addHobby(String hobby) {
  this.hobby = Optional.ofNullable(this.hobby).orElse(new ArrayList<>());
  this.hobby.add(hobby);
}
public void addGift(String day, String gift) {
  this.gift = Optional.ofNullable(this.gift).orElse(new HashMap<>());
  this.gift.put(day, gift);
}
public void setVitalStatistics(int bust, int waist, int hips) {
  this.bust = bust;
  this.waist = waist;
  this.hips = hips;
}
public static void main(String[] args) {
  GirlFriend myGirlFriend = Builder.of(GirlFriend::new)
    .with(GirlFriend::setName, "小美")
    .with(GirlFriend::setAge, 18)
    .with(GirlFriend::setVitalStatistics, 33, 23, 33)
    .with(GirlFriend::setBirthday, "2001-10-26")
    .with(GirlFriend::setAddress, "上海浦東")
    .with(GirlFriend::setMobile, "18688888888")
    .with(GirlFriend::setEmail, "[email protected]")
    .with(GirlFriend::setHairColor, "淺棕色帶點(diǎn)微卷")
    .with(GirlFriend::addHobby, "逛街")
    .with(GirlFriend::addHobby, "購物")
    .with(GirlFriend::addHobby, "買東西")
    .with(GirlFriend::addGift, "情人節(jié)禮物", "LBR 1912女王時(shí)代")
    .with(GirlFriend::addGift, "生日禮物", "迪奧烈焰藍(lán)金")
    .with(GirlFriend::addGift, "紀(jì)念日禮物", "阿瑪尼紅管唇釉")
    // 等等等等 ...
    .build();
  }
}

/**
* 通用的 Builder 模式構(gòu)建器
*
* @author: CipherCui
* @since 2019/8/29
*/
public class Builder {
  private final Supplierinstantiator;
  private List modifiers = new ArrayList<>();
  public Builder(Supplierinstantiator){
    this.instantiator = instantiator;
  }
  public staticBuilderof(Supplierinstantiator){
    return new Builder<>(instantiator);
  }
  publicBuilderwith(Consumer1consumer, P1 p1){
    Consumerc = instance -> consumer.accept(instance, p1);
    modifiers.add(c);
    return this;
  }
  publicBuilderwith(Consumer2consumer, P1 p1, P2 p2){
    Consumerc = instance -> consumer.accept(instance, p1, p2);
    modifiers.add(c);
    return this;
  }
  publicBuilderwith(Consumer3consumer, P1 p1, P2 p2, P3 p3){
    Consumerc = instance -> consumer.accept(instance, p1, p2, p3);
    modifiers.add(c);
    return this;
  }
  public T build() {
    T value = instantiator.get();
    modifiers.forEach(modifier -> modifier.accept(value));
    modifiers.clear();
    return value;
  }
/**
* 1 參數(shù) Consumer
*/
@FunctionalInterface
public interface Consumer1 {
  void accept(T t, P1 p1);
}
/**
* 2 參數(shù) Consumer
*/
@FunctionalInterface
public interface Consumer2 {
  void accept(T t, P1 p1, P2 p2);
}
/**
* 3 參數(shù) Consumer
*/
@FunctionalInterface
  public interface Consumer3 {
    void accept(T t, P1 p1, P2 p2, P3 p3);
  }
}

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