java经典例子.docVIP

java经典例子 1.一个饲养员给动物喂食物的例子体现JAVA中的面向对象思想,接口（抽象类）的用处 package com.softeem.demo; /** *@author leno *动物的接口 */ interface Animal { public void eat(Food food); } /** *@author leno *一种动物类:猫 */ class Cat implements Animal { public void eat(Food food) { System.out.println(小猫吃 + food.getName()); } } /** *@author leno *一种动物类:狗 */ class Dog implements Animal { public void eat(Food food) { System.out.println(小狗啃 + food.getName()); } } /** *@author leno *食物抽象类 */ abstract class Food { protected String name; public String getName() { return name; } public void setName(String name) { this.name = name; } } /** *@author leno *一种食物类:鱼 */ class Fish extends Food { public Fish(String name) { this.name = name; } } /** *@author leno *一种食物类:骨头 */ class Bone extends Food { public Bone(String name) { this.name = name; } } /** *@author leno *饲养员类 * */ class Feeder { /** *饲养员给某种动物喂某种食物 *@param animal *@param food */ public void feed(Animal animal, Food food) { animal.eat(food); } } /** *@author leno *测试饲养员给动物喂食物 */ public class TestFeeder { public static void main(String[] args) { Feeder feeder = new Feeder(); Animal animal = new Dog(); Food food = new Bone(肉骨头); feeder.feed(animal, food); //给狗喂肉骨头 animal = new Cat(); food = new Fish(鱼); feeder.feed(animal, food); //给猫喂鱼 } } 2.做一个单子模式的类，只加载一次属性文件 package com.softeem.demo; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.util.Properties; /** * @authorleno 单子模式，保证在整个应用期间只加载一次配置属性文件 */ public class Singleton { private static Singleton instance; private static final String CONFIG_FILE_PATH = E:\\config.properties; private Properties config; private Singleton() { config = new Properties(); InputStream