定义一个由builder来构造的实体类

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * description: Java Builder模式练习
 * @version v1.0
 * @author w
 * @date 2021年7月7日上午11:37:49
 **/
@AllArgsConstructor
@Data
@NoArgsConstructor
public class User {
    private String id ;
    private String name ;
    private Integer age ;

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

    public static class Builder{
        private String id ;
        private String name ;
        private Integer age ;

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

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

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

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

        public User build2() {
            return new User(this.id , this.name , this.age);
        }

    }

    public User(Builder builder) {
        this.id = builder.id;
        this.name = builder.name ;
        this.age = builder.age;
    }

}

public class TestBuilder {
    public static void main(String[] args) {
        User user = User.builder().id("1").name("xiaoming").age(18).build();
        System.out.println(user);
    }
}