引用： http://www.jianshu.com/p/1ddb69f1f67e 引用经典Builder/变种Builder模式及自动化生成代码插件
插件： http://blog.csdn.net/SoberChina/article/details/72953989?locationNum=2&fps=1

例子1:

使用 new Person.Builder().name("小猪").age("20").build();

1.Person类的构造函数是私有的。这样就不能直接实例化这个类
2.Person类是不可变的。里面的属性都是final的。只能在构造函数中初始化。然后提供了属性的get函数，可以去获取值。

public class Person {
    private final String name; //变量都是final 只能在构造函数中初始化
    private final String age;

    private Person(Builder builder) {
        name = builder.name;
        age = builder.age;
    }

    public String getName() {
        return name;
    }

    public String getAge() {
        return age;
    }

    public static final class Builder {
        private String name;
        private String age;

        public Builder() {
        }

        public Builder name(String val) {
            name = val;
            return this;
        }

        public Builder age(String val) {
            age = val;
            return this;
        }

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

例子2

使用 Person.newBuilder().name("小猪").age("20").build();

1、使用可以减少new，使用newBuilder（）
2、有copy功能 newBuilder(Person copy)

/**
 * Created by lch on 2017/10/26.
 */

public class Person {
    private final String name; //变量都是final 只能在构造函数中初始化
    private final String age;

    private Person(Builder builder) {
        name = builder.name;
        age = builder.age;
    }

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

    public static Builder newBuilder(Person copy) {
        Builder builder = new Builder();
        builder.name = copy.name;
        builder.age = copy.age;
        return builder;
    }

    public String getName() {
        return name;
    }

    public String getAge() {
        return age;
    }

    

    public static final class Builder {
        private String name;
        private String age;

        public Builder() {
        }

        public Builder name(String val) {
            name = val;
            return this;
        }

        public Builder age(String val) {
            age = val;
            return this;
        }

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