好处：
能保证重叠构造器模式的安全性；
能保证JAVABeans模式的可读性；
package cn.lonecloud.builder;
/**
* 使用内部类构建器来对这个类进行构造
* @Title: MyConstractor.java
* @Package cn.lonecloud.builder
* @Description:
* @author lonecloud
* @webSite http://wwww.lonecloud.cn
* @date 2016年9月12日 上午10:17:11
*/
public class MyConstractor {
//some field of class
private final int size;
private final int servings;
private final int fat;
private final int sodium;
private final int age;
//using getMethod
public int getSize() {
return size;
}
public int getServings() {
return servings;
}
public int getFat() {
return fat;
}
public int getSodium() {
return sodium;
}
public int getAge() {
return age;
}
@Override
public String toString() {
return "MyConstractor [size=" + size + ", servings=" + servings
+ ", fat=" + fat + ", sodium=" + sodium + ", age=" + age + "]";
}
//using constractMethod init field
private MyConstractor(Builder builder){
this.size=builder.size;
this.servings=builder.servings;
this.fat=builder.fat;
this.sodium=builder.sodium;
this.age=builder.age;
}
//using static class to set this class
public static class Builder{
//some field of staticClass
private final int size;
private final int servings;
//using method to set field
private int fat=0;
private int sodium=0;
private int age=0;
//using constractorMethod to init this final field
public Builder(int size, int servings) {
this.size = size;
this.servings = servings;
}
//write method to set field;
public Builder fat(int fat){
this.fat=fat;
return this;
}
public Builder sodium(int sodium){
this.sodium=sodium;
return this;
}
public Builder age(int age){
this.age=age;
return this;
}
//return MyConstractor
public MyConstractor build(){
return new MyConstractor(this);
}
}
}
测试类：
package cn.lonecloud.constactor;
import org.junit.Test;
import cn.lonecloud.builder.MyConstractor;
public class MyTest {
@Test
public void constractorTest(){
MyConstractor myConstractor = new MyConstractor.Builder(1,2).age(100).build();
System.out.println(myConstractor.toString());
}
}