设计模式-建造者模式

public class User{
    private String name;
    private String password;
    private String nickName;
    private int age;

    //将构造方法私有化
    private User(String name,String password,String nickName,int age){
        this.name=name;
        this.password=password;
        this.nickName=nickName;
        this.age=age;
    }

    public static class UserBuilder{
        private String name;
        private String password;
        private String nickName;
        private int age;

        private UserBuilder(){

        }
        // 链式调用设置各个属性值，返回 this，即 UserBuilder
        public UserBuilder name(String name) {
            this.name = name;
            return this;
        }

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

        public UserBuilder nickName(String nickName){
            this.nickName=nickName;
            return this;
        }

        public UserBuilder age(int age){
            this.age=age;
            return this;
        }

        //bulid()方法负责将userBuilder中设置好的属性，赋值到user中
        //可以在“复制”之前做点检验
        public User build(){
            if(name==null || password==null){
                throw  new RuntimeException("name is null");
            }
            if(age<=0 || age >=150){
                throw new RuntimeException("age is not allow");
            }
            if(nickName==null){
                nickName=name;
            }
            return new User(name,password,nickName,age);
        }

        // 静态方法，用于生成一个 Builder，这个不一定要有，不过写这个方法是一个很好的习惯，
        // 有些代码要求别人写 new User.UserBuilder().a()...build() 看上去就没那么好
        public static UserBuilder builder() {
            return new UserBuilder();
        }


    }


}

/**
 * 建造这模式
 * 可以使用 lombok
 */
public class TestBuilder {
    public static void main(String[] args) {
        User d = User.UserBuilder.builder()
                .name("zhangs")
                .password("13212312")
                .age(25)
                .build();
    }

}