java8新特性接口使用教程：听说你还在new对象
java8新特性接口使用教程：听说你还在new对象适用于所有类，不需要改造原来类，不需要 lombok 插件支持。这里不再介绍其他 Builder 实现方式，直接祭出最实用的通用Builder：public class GirlFriend{ private String name; private int age; private int bust; private int waist; private int hips; private List<String> hobby; private String birthday; private String address; private String mobile; private Stringe mail; private Stringhair Color; private
来源：cipher ciphermagic.cn/java8-builder.html
程序员经常会遇到灵魂拷问：你有对象吗？
没有，但我可以 new 一个！
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<String> hobby;
private String birthday;
private String address;
private String mobile;
private Stringe mail;
private Stringhair Color;
private Map <String String> gift;
//等等等等...
//省略getter&setter...
publicstaticvoidmain(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("上海浦东");
myGirlFriend.setMobile("18688888888");
myGirlFriend.setEmail("pretty-xiaomei@qq.com");
myGirlFriend.setHairColor("浅棕色带点微卷");
List<String>hobby=newArrayList<>();
hobby.add("逛街");
hobby.add("购物");
hobby.add("买东西");
myGirlFriend.setHobby(hobby);
Map<String String>gift=newHashMap<>();
gift.put("情人节礼物" "LBR1912女王时代");
gift.put("生日礼物" "迪奥烈焰蓝金");
gift.put("纪念日礼物" "阿玛尼红管唇釉");
myGirlFriend.setGift(gift);
//等等等等...
}
}
GirlFriend{name='小美'
age=18
bust=33
waist=23
hips=33
hobby=[逛街 购物 买东西]
birthday='2001-10-26'
address='上海浦东'
mobile='18688888888'
email='pretty-xiaomei@qq.com'
hairColor='浅棕色带点微卷'
gift={情人节礼物=LBR1912女王时代 生日礼物=迪奥烈焰蓝金 纪念日礼物=阿玛尼红管唇釉}
}
GirlFriend 是很美，但写起来也太麻烦了吧。
说说缺点：实例化和设置属性分开，不好维护；变量名重复写。
莫慌，看法宝~
这里不再介绍其他 Builder 实现方式，直接祭出最实用的通用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：
publicclassGirlFriend{
//省略属性...
//省略getter&setter...
//为了演示方便，加几个聚合方法
publicvoidaddHobby(Stringhobby){
this.hobby=Optional.ofNullable(this.hobby).orElse(newArrayList<>());
this.hobby.add(hobby);
}
publicvoidaddGift(Stringday Stringgift){
this.gift=Optional.ofNullable(this.gift).orElse(newHashMap<>());
this.gift.put(day gift);
}
publicvoidsetVitalStatistics(intbust intwaist inthips){
this.bust=bust;
this.waist=waist;
this.hips=hips;
}
publicstaticvoidmain(String[]args){
GirlFriendmyGirlFriend=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" "LBR1912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
*@since2019/8/29
*/
public class Builder<T>{
private final Supplier<T>instantiator;
private List<consumer<T>> modifiers=newArrayList<>();
public Builder(Supplier<T> instantiator){
this.instantiator=instantiator;
}
public static<T>Builder<T>of(Supplier<T>instantiator){
return new Builder<>(instantiator);
}
public <P1>Builder<T>with(Consumer1<T P1>consumer P1p1){
Consumer<T>c=instance->consumer.accept(instance p1);
modifiers.add(c);
return this;
}
public <P1 P2>Builder<T>with(Consumer2<T P1 P2>consumer P1p1 P2p2){
Consumer<T>c=instance->consumer.accept(instance p1 p2);
modifiers.add(c);
return this;
}
public <P1 P2 P3>Builder<T>with(Consumer3<T P1 P2 P3>consumer P1p1 P2p2 P3p3){
Consumer<T>c=instance->consumer.accept(instance p1 p2 p3);
modifiers.add(c);
return this;
}
public T build(){
Tvalue=instantiator.get();
modifiers.forEach(modifier->modifier.accept(value));
modifiers.clear();
return value;
}
/**
*1参数Consumer
*/
@FunctionalInterface
public interface Consumer1<T P1>{
void accept(Tt P1p1);
}
/**
*2参数Consumer
*/
@FunctionalInterface
public interface Consumer2<T P1 P2>{
void accept(Tt P1p1 P2p2);
}
/**
*3参数Consumer
*/
@FunctionalInterface
public interface Consumer3<T P1 P2 P3>{
void accept(Tt P1p1 P2p2 P3p3);
}
}
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。
快用你的 Builder 建个对象吧~
