Builder 设计模式

优点

• 不需要知道参数顺序, 参数设置顺序可以任意组合
• 可读性高, 代码清晰
• 可扩展性强, 可以添加新的参数

实现

public class User {
    private String name;
    private int age;
    private String address;

    private User(Builder builder) {
        this.name = builder.name;
        this.age = builder.age;
        this.address = builder.address;
    }

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

    public static class Builder {
        private String name;
        private int age;
        private String address;

        public Builder setName(String name) {
            this.name = name;
            return this;
        }
        public Builder setAge(int age) {
            this.age = age;
            return this;
        }
        public Builder setAddress(String address) {
            this.address = address;
            return this;
        }

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

调用

    User user = User.builder()
            .setName("John")
            .setAge(30)
            .setAddress("123 Main St")
            .build();