构建器模式(Builder Pattern):
View Code
package edu.sjtu.erplab.builder; public class NutritionFacts { private final int servingSize; private final int servings; private final int calories; private final int fat; private final int sodium; private final int carbohydrate; // 构造器,静态内部类 public static class Builder { // 必要参数 private final int servingSize; private final int servings; // 可选参数 private int calories = 0; private int fat = 0; private int carbohydrate = 0; private int sodium = 0; public Builder(int servingSize, int servings) { this.servingSize = servingSize; this.servings = servings; } public Builder calories(int val) { calories = val; return this;//返回Builder类对象本身,以便把调用链接起来 } public Builder fat(int val) { fat = val; return this; } public Builder carbohydrate(int val) { carbohydrate = val; return this; } public Builder sodium(int val) { sodium = val; return this; } public NutritionFacts build() { return new NutritionFacts(this); } } private NutritionFacts(Builder builder) { servingSize = builder.servingSize; servings = builder.servings; calories = builder.calories; fat = builder.fat; sodium = builder.sodium; carbohydrate = builder.carbohydrate; } @Override public String toString() { // TODO Auto-generated method stub return "["+ "servingSize:"+servingSize+ ",servings:"+servings+ ",calories:"+calories+ ",fat:"+fat+ ",sodium:"+sodium+ ",carbohydrate:"+carbohydrate+ "]"; } public static void main(String[] args) { NutritionFacts cocaCola = new NutritionFacts.Builder(240, 8) .calories(100).sodium(35).carbohydrate(27).build(); System.out.println(cocaCola); } }