一般新建对象我们都是直接new一下

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);}}没问题，老铁！但如果对象的属性太多，咋办？

public class GirlFriend {private String name;private int age;private int bust;private int waist;private int hips;private List hobby;// 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);// 等等等等 ...}}

而Java8通用Builder适用于所有类，不需要改造原来类，不需要 lombok 插件支持。

先看看使用姿势：

public class GirlFriend {// 省略属性 ...// 省略 getter & setter ...

    // 为了演示方便，加几个聚合方法
    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, "上海浦东")
                .with(GirlFriend::setMobile, "18688888888")
                .with(GirlFriend::setEmail, "pretty-xiaomei@qq.com")
                .with(GirlFriend::setHairColor, "浅棕色带点微卷")
                .with(GirlFriend::addHobby, "逛街")
                .with(GirlFriend::addHobby, "购物")
                .with(GirlFriend::addHobby, "买东西")
                .with(GirlFriend::addGift, "情人节礼物", "LBR 1912女王时代")
                .with(GirlFriend::addGift, "生日礼物", "迪奥烈焰蓝金")
                .with(GirlFriend::addGift, "纪念日礼物", "阿玛尼红管唇釉")
                // 等等等等 ...
                .build();
    }
}
看到了吗！实例化和属性设置在同一条语句执行，链式操作，一路点点点，清爽！

Talk is cheap, show me the code：

/**

• 通用的 Builder 模式构建器
  *
• @author: CipherCui
• @since 2019/8/29
  */
  public class Builder {
  private final Supplier instantiator;
  private List> modifiers = new ArrayList<>();
  public Builder(Supplier instantiator) {
  this.instantiator = instantiator;
  }
  public static Builder of(Supplier instantiator) {
  return new Builder<>(instantiator);
  }
  public Builder with(Consumer1 consumer, P1 p1) {
  Consumer c = instance -> consumer.accept(instance, p1);
  modifiers.add(c);
  return this;
  }
  public Builder with(Consumer2 consumer, P1 p1, P2 p2) {
  Consumer c = instance -> consumer.accept(instance, p1, p2);
  modifiers.add(c);
  return this;
  }
  public Builder with(Consumer3 consumer, P1 p1, P2 p2, P3 p3) {
  Consumer c = 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 参数 Consumer
    */
    @FunctionalInterface
    public interface Consumer1 {
    void accept(T t, P1 p1);
    }
    /** ,>
  • 2 参数 Consumer
    */
    @FunctionalInterface
    public interface Consumer2 {
    void accept(T t, P1 p1, P2 p2);
    }
    /** ,>
  • 3 参数 Consumer
    */
    @FunctionalInterface
    public interface Consumer3 {
    void accept(T t, P1 p1, P2 p2, P3 p3);
    }
    }
    这个示例最多支持三个参数的设置属性方法，也完全够用了。如果要扩展也很容易，依葫芦画瓢，添加多个参数的Consumer。 ,>
  ,>,>,>,>,>

参考：http://www.ciphermagic.cn/java8-builder.html

• 点赞
• 收藏
• 分享
• • 文章举报

陈晨辰~ 发布了143 篇原创文章 · 获赞 64 · 访问量 12万+ 私信 关注