設計模式建造者模式的java實現類

第一步、建立一個要被構建的類 Persion類並宣告屬性

package com.chinamsp.mytest.pattern.builder;


class Persion {

    private String name;
    private Integer age;
    private String address;
    private String phone;

}

第二步、建立一個共有的構造者類

package com.chinamsp.mytest.pattern.builder;


class Persion {

    private String name;
    private Integer age;
    private String address;
    private String phone;


    public static class Builder {
       /** 此處的屬性和上邊的被構造類屬性對應 */
        private String name;
        private Integer age;
        private String address;
        private String phone;
       
        /** 賦值各個屬性方法 */
        public Builder name(String name) {
            this.name = name;
            return this;
        }

        public Builder age(Integer age) {
            this.age = age;
            return this;
        }

        public Builder address(String address) {
            this.address = address;
            return this;
        }

        public Builder phone(String phone) {
            this.phone = phone;
            return this;
        }
    }
}




 

第三步、在被構造物件中宣告有參構造，在構造物件中建立build方法返回被構造物件

package com.chinamsp.mytest.pattern.builder;


class Persion {

    private String name;
    private Integer age;
    private String address;
    private String phone;

  
    public Persion(Builder builder) {
        this.name = builder.name;
        this.age = builder.age;
        this.address = builder.address;
        this.phone = builder.phone;
    }


    public static class Builder {
        private String name;
        private Integer age;
        private String address;
        private String phone;

        public Builder name(String name) {
            this.name = name;
            return this;
        }

        public Builder age(Integer age) {
            this.age = age;
            return this;
        }

        public Builder address(String address) {
            this.address = address;
            return this;
        }

        public Builder phone(String phone) {
            this.phone = phone;
            return this;
        }

        public Persion build() {
            return new Persion(this);
        }
    }

    @Override
    public String toString() {
        return "Persion{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }
}
 

第四步驟、宣告一個靜態的獲取構造物件的方法

package com.chinamsp.mytest.pattern.builder;


class Persion {

    private String name;
    private Integer age;
    private String address;
    private String phone;

    public static Builder builder() {
        Builder builder = new Builder();
        return builder;
    }

    public Persion(Builder builder) {
        this.name = builder.name;
        this.age = builder.age;
        this.address = builder.address;
        this.phone = builder.phone;
    }


    public static class Builder {
        private String name;
        private Integer age;
        private String address;
        private String phone;

        public Builder name(String name) {
            this.name = name;
            return this;
        }

        public Builder age(Integer age) {
            this.age = age;
            return this;
        }

        public Builder address(String address) {
            this.address = address;
            return this;
        }

        public Builder phone(String phone) {
            this.phone = phone;
            return this;
        }

        public Persion build() {
            return new Persion(this);
        }
    }

    @Override
    public String toString() {
        return "Persion{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }
}




 

下面呼叫試試看

 public static void main(String[] args) {
        Persion per = Persion.builder()
                .address("xxx")
                .age(20)
                .name("賬單")
                .phone("34213123")
                .build();
        System.out.println(per.toString());
    }

到此已經完成了，概念性的東西小夥伴們直接去維基百科搜尋吧，這個小小的demo僅僅提供參考

下面是個人理解

建造者模式有點是可以根據實際業務場景去判斷各個引數動態的建立一個統一的入引數物件，在一半類中屬性繁多的情況下這麼去建立一個物件賦值屬性很清晰優雅