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……