在Builder模式中，通常只有一个参数化构造函数，其余的属性可以通过方法链式调用来设置。如果想要添加额外的构造函数，可以在Builder类中添加一个新的静态方法来返回一个已经初始化好的Builder对象。

代码示例：

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

// 构造函数私有，只能通过Builder类来创建对象 private Person(String name, int age, String address) { this.name = name; this.age = age; this.address = address; }

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

  public PersonBuilder() {
  }
  
  public PersonBuilder withName(String name) {
     this.name = name;
     return this;
  }
  
  public PersonBuilder withAge(int age) {
     this.age = age;
     return this;
  }
  
  public PersonBuilder withAddress(String address) {
     this.address = address;
     return this;
  }
  
  public Person build() {
     return new Person(name, age, address);
  }
  
  // 新的静态方法
  public static PersonBuilder withDefault() {
     return new PersonBuilder()
        .withName("John")
        .withAge(30)
        .withAddress("123 Main St.");
  }

} }

通过这种方式，我们可以在Builder模式中添加额外的构造函数并提供默认值。例如，我们可以这样创建一个新的Person对象：

Person person = Person.PersonBuilder.withDefault().build();