建造者模式的特点就是
1.如果实体类有多个属性，而在实现实例时不需要将所有属性全部赋值
2.可以按照需要灵活地选择某些属性赋值，就能够得到一个实例
在不使用建造者模式情况下，这个需要的代码量就会很多
代码如下：
public class Person { private String name = null; private int age = -1; private String sex = null; private String father = null; private String mother = null; private String husbandOrwife = null; private Person(PersonBuilder pb){ this.name = pb.name; this.age = pb.age; this.father = pb.father; this.mother = pb.mother; this.sex = pb.sex; this.husbandOrwife = pb.husbandOrwife; } static class PersonBuilder{ String name = null; int age = -1; String sex = null; String father = null; String mother = null; String husbandOrwife = null; public PersonBuilder setName(String name){ this.name = name; return this; } public PersonBuilder setAge(int age){ this.age = age; return this; } public PersonBuilder setSex(String sex){ this.sex = sex; return this; } public PersonBuilder setFather(String father){ this.father = father; return this; } public PersonBuilder setMother(String mother){ this.mother = mother; return this; } public PersonBuilder setHusbandOrWife(String husbandOrwife){ this.husbandOrwife = husbandOrwife; return this; } public Person build(){ return new Person(this); } } @Override public String toString(){ return "[ name="+name+", age="+age+", sex="+sex+", father="+father+", mother="+mother+", husbandOrwife="+husbandOrwife+" ]"; } }
使用Builder得到实例的代码如下：
@Test public void Test2(){ Person a = new Person.PersonBuilder().setName("拉拉").setMother("格温").build();
Person b = new Person.PersonBuilder().setAge(11).setFather("皮特儿").build();
System.out.println(a);
}
总结：
这个和聚合操作的格式类似，可以调用不同数量，不同种类的方法，最后只要回归到一个终结操作就可以，而这里的终结操作就是build()。
建造者模式的关键是，1.构建器是实体类的内部静态类
2.实体类有一个构造器，其参数是构建器（Builder）
3.通过这个构建器可以将实例的属性赋值。
4.构建器的build()方法，返回的是通过构造器创造的实例
Constructor(Builder b);
static class Builder{ Constructor build(){ return new Constructor(thisbuilder); }
}
原文：https://www.cnblogs.com/wqq-blog/p/10580823.html