JavaBuilder模式详解与使用方法

public class User {
    private final String name;
    private final int age;
    private final String email;
    private final String phone;

    // 私有构造函数，由Builder调用
    private User(Builder builder) {
        this.name = builder.name;
        this.age = builder.age;
        this.email = builder.email;
        this.phone = builder.phone;
    }

    // Getter方法
    public String getName() { return name; }
    public int getAge() { return age; }
    public String getEmail() { return email; }
    public String getPhone() { return phone; }

    // 静态内部Builder类
    public static class Builder {
        private String name;
        private int age;
        private String email;
        private String phone;

        public Builder setName(String name) {
            this.name = name;
            return this; // 返回this以支持链式调用
        }

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

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

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

        // build方法返回最终的User对象
        public User build() {
            // 可在此处添加参数校验
            if (name == null || name.isEmpty()) {
                throw new IllegalArgumentException("Name is required");
            }
            return new User(this);
        }
    }
}

User user = new User.Builder()
    .setName("Alice")
    .setAge(28)
    .setEmail("alice@example.com")
    .setPhone("138-0000-0000")
    .build();

User minimalUser = new User.Builder()
    .setName("Bob")
    .setAge(25)
    .build();