chapter14_剩下的模式

• 生成器模式

  (1) 又称建造者模式，将构建过程和表示过程进行分离，让（参数）构建过程变得更加的简单和直观。另一种差不多的解释：建造者模式（Builder Pattern），是创造性模式之一，Builder 模式的目的则是为了将对象的构建与展示分离。Builder 模式是一步一步创建一个复杂对象的创建型模式，它允许用户在不知道内部构建细节的情况下，可以更精细地控制对象的构造流程。

  (2) 示例

    public class Person {
  
        private String name;
        private String sex;
        private double height;
        private double weight;
        private String country;
        private String homeTown;
  
        private Person(String name, String sex,
               double height, double weight,
               String country, String homeTown) {
  
            this.name = name;
            this.sex = sex;
            this.height = height;
            this.weight = weight;
            this.country = country;
            this.homeTown = homeTown;
        }
  
        static final class Builder {
  
            private String name;
            private String sex;
            private double height;
            private double weight;
            private String country;
            private String homeTown;
  
            public Builder setName(String name) {
  
                this.name = name;
                return this;
            }
  
            public Builder setSex(String sex) {
  
                this.sex = sex;
                return this;
            }
  
            public Builder setHeight(double height) {
  
                this.height = height;
                return this;
            }
  
            public Builder setWeight(double weight) {
          
                this.weight = weight;
                return this;
            }
  
            public Builder setCountry(String country) {
  
                this.country = country;
                return this;
            }
  
            public Builder setHomeTown(String homeTown) {
  
                this.homeTown = homeTown;
                return this;
            }
  
            public Person build() {
  
                return new Person(name, sex, height, weight, country, homeTown);
            }
        }
    }
  

  测试

    public class TestPerson {
  
        public static void main(String[] args) {
  
            Person.Builder builder = new Person.Builder();
  
            Person me = builder.setName("BoCHEN")
                    .setCountry("China")
                    .setHeight(1.78)
                    .setHomeTown("LN")
                    .setSex("Male")
                    .setWeight(61.2).build();
  
            System.out.println();
        }
  

  (3) 优点

  1° 可读性强

  链式调用, 一行搞定, 不用好几行各种set了

  2° 可选择性强

  如果采取构造函数的形式的话, 当内部域很多时, 需要创建一大堆构造函数; 使用builder模式可以只set那些需要set的参数, 其他可以使用默认值

• 未完待续……