构造器模式

构造器模式

1. 意图

   • 将一个复杂对象的构建和表示分离，使得相同的构建能创建不同的表示。

2. 解释

   案例：想象一个角色扮演游戏的特征生成器。最简单的选择是让计算机为你创建角色。如果你想手动选择特征的细节像职业、性别、头发的颜色等。特征的产生是一个循序渐进的过程，当所有选择都就绪时结束。

   简单说：允许你在避免函数污染的情况下创建不同特征的对象。当一个对象有好几种特征时或当创建对象需要很多步骤时。

3. 样例

   //盔甲
   public enum Armor {
       CHAIN_MAIL("Chain Mail"),
       CLOTHES("Clothes"),
       LEATHER("leather"),
       PLATE("plate");
   
       private String description;
   
       Armor(String description) {
           this.description = description;
       }
   
       public String getDescription() {
           return description;
       }
   }
   

   //头发的颜色
   public enum HairColor {
       BLACK,
       BLOND,
       BROWN,
       RED,
       WHITE;
   }
   

   //头发类型
   public enum HairType {
       BALD("bald"),
       CURLY("curly"),
       LONG_CURLY("long curly"),
       LONG_STRAIGHT("long straight"),
       SHORT("short");
   
       private String description;
   
   
       HairType(String description) {
           this.description = description;
       }
   }
   

   //职业
   public enum Profession {
       MAGE,
       PRIEST,
       THIEF,
       WARRIOR;
   }
   

   //武器
   public enum Weapon {
       AXE,
       BOW,
       DAGGER,
       SWORD,
       WARHAMMER;
   
   }
   

   //角色
   public final class Hero {
       private Armor armor;
       private Weapon weapon;
       private HairType hairType;
       private HairColor hairColor;
       private Profession profession;
   
       public Hero(Builder builder){
           this.armor = builder.armor;
           this.weapon = builder.weapon;
           this.hairType = builder.hairType;
           this.hairColor = builder.hairColor;
           this.profession = builder.profession;
       }
   
       public Armor getArmor() {
           return armor;
       }
   
       public Weapon getWeapon() {
           return weapon;
       }
   
       public HairType getHairType() {
           return hairType;
       }
   
       public HairColor getHairColor() {
           return hairColor;
       }
   
       public Profession getProfession() {
           return profession;
       }
   
       public static class Builder {
           private Armor armor;
           private HairType hairType;
           private HairColor hairColor;
           private Profession profession;
           private Weapon weapon;
           private String name;
   
           public Builder(Profession profession, String name) {
               this.profession = profession;
               this.name = name;
           }
   
           public Hero build() {
               return new Hero(this);
           }
   
           Builder withArmor(Armor armor) {
               this.armor = armor;
               return this;
           }
   
           Builder withHairType(HairType hairType) {
               this.hairType = hairType;
               return this;
           }
   
           Builder withHairColor(HairColor hairColor) {
               this.hairColor = hairColor;
               return this;
           }
   
           Builder withWeapon(Weapon weapon) {
               this.weapon = weapon;
               return this;
           }
       }
   
   }
   

   public class Main {
       public static void main(String[] args) {
           var riobard = new Hero.Builder(Profession.MAGE, "Riobard").
                   withHairColor(HairColor.BLACK).
                   withWeapon(Weapon.DAGGER)
                   .build();
           
       }
   }
   

4. 结构图

5. 适用性

• 创建复杂对象的算法应该独立于其组成对象的部件和组装的方式。

• 构造的过程必须允许对构造的对象进行不同的表示。