重叠构造器模式

                                                                                                                        ——不能很好地扩展:

public class Person {private String name;    // 必填private int age;        // 必填private String address; // 可选private String email;   // 可选private String phone;   // 可选private String occupation; // 可选// 无参构造方法public Person(){}public Person(String name, int age) {this.name = name;this.age = age;}public Person(String name, int age, String address) {this(name, age, adress, null);}public Person(String name, int age, String address, String email) {this(name, age, adress, email, null);}public Person(String name, int age, String address, String email, String phone) {this(name, age, adress, email, phone, null);}public Person(String name, int age, String address, String email, String phone, String occupation) {this.name = name;this.age = age;this.address = address;this.email = email;this.phone = phone;this.occupation = occupation;}// Getters and setters
}

JavaBeans模式

                                                                                                     ——允许不一致性，要求可变性：

public class Person {private String name;    // 必填private int age;        // 必填private String address; // 可选private String email;   // 可选private String phone;   // 可选private String occupation; // 可选// 无参构造方法public Person(){}// setterspublic void setName (String name)       { this.name = name;}public void setAge(String age)          { this.age = age;}public void setAddress (String address) { this.address = address;}public void setEmail (String email)     { this.email = email;}public void setPhone (String phone)     { this.phone = phone;}public void setOccupation (String occupation) { this.occupation = occupation;}
}

Person person = new Person();
person.setName("name");
person.setAge("age");  
person.setAddress("address"); 
person.setEmail("email");     
person.setPhone("phone");    
person.setOccupation ("occupation"); 

生成器模式：

public class Person {private String name;    // 必填private int age;        // 必填private String address; // 可选private String email;   // 可选private String phone;   // 可选private String occupation; // 可选private Person(Builder builder) {this.name = builder.name;this.age = builder.age;this.address = builder.address;this.email = builder.email;this.phone = builder.phone;this.occupation = builder.occupation;}// Getterspublic static class Builder {private String name;private int age;private String address;private String email;private String phone;private String occupation;public Builder(String name, int age) {this.name = name;this.age = age;}public Builder address(String address) {this.address = address;return this;}public Builder email(String email) {this.email = email;return this;}public Builder phone(String phone) {this.phone = phone;return this;}public Builder occupation(String occupation) {this.occupation = occupation;return this;}public Person build() {return new Person(this);}}
}

使用示例： 

Person person = new Person.Builder("John", 25).address("123 Main St").email("john@example.com").build();

在上述示例中，Person 类使用了一个内部的 Builder 类来构建对象。必填的参数通过构造函数传入，而可选的参数则通过链式调用建造者的方法进行设置。最后，通过调用 build() 方法来创建最终的 Person 对象。

使用生成器模式，你可以根据需要选择要设置的可选参数，而不必担心参数顺序或构造函数重载的问题。这种模式提供了更灵活和可扩展的方式来创建对象，并且可以轻松地处理不同参数组合的情况。