学习程序的最好方式就是编代码实现它，这里我们假设一个场景为要开一个晚会，晚会的流程为：1.晚会开始；2.唱歌；3.舞蹈；4.小品；5结束。
1、新建java项目：party
2、在party项目中新建类EveningParty
package com.gmail.lsgjzhuwei;
public class EveningParty {
public static void main(String[] args)
{
}
}在EveningParty类中实现晚会的流程，新建process函数，在process函数中实现整个晚会流程，具体代码为：
public void process()
{
//1.晚会开始
//2.唱歌
//3.舞蹈
//4.小品
//5.晚会结束
System.out.println("晚会开始");
//唱歌
Singable singable = new Liudehua();
singable.sing();
//跳舞
Dancleable dancleable = new Xiaohudui();
dancleable.dance();
//小品
Essayable essayable = new Zhaobenshan();
essayable.essay();
}package com.gmail.lsgjzhuwei;
/**
* @author Leo Chu
*Singable接口用于实现唱歌
* 2014-8-24
*/
public interface Singable {
public void sing();
}
package com.gmail.lsgjzhuwei;
/**
* @author Leo Chu
*Dancleable接口用于实现跳舞
* 2014-8-24
*/
public interface Dancleable {
public void dance();
}
package com.gmail.lsgjzhuwei;
/**
* @author Leo Chu
*Essayable接口用于实现小品
* 2014-8-24
*/
public interface Essayable {
public void essay();
}
3.1定义Liudehua类实现Singable接口
package com.gmail.lsgjzhuwei;
public class Liudehua implements Singable {
public void sing() {
// TODO Auto-generated method stub
System.out.println("刘德华演唱中国人");
}
}
3.2定义Naying实现Sinable接口
package com.gmail.lsgjzhuwei;
public class Naying implements Singable
{
public void sing()
{
System.out.println("那英演唱：雾里看花");
}
}
package com.gmail.lsgjzhuwei;
public class Xiaohudui implements Dancleable {
public void dance() {
// TODO Auto-generated method stub
System.out.println("小虎队舞蹈：爱");
}
}
3.4定义Chenailian实现Dancleable接口
package com.gmail.lsgjzhuwei;
public class Chenailian implements Dancleable {
public void dance() {
// TODO Auto-generated method stub
System.out.println("陈爱莲舞蹈：天鹅舞");
}
}
3.5定义Zhaobenshan实现Essayable接口
package com.gmail.lsgjzhuwei;
public class Zhaobenshan implements Essayable {
public void essay() {
// TODO Auto-generated method stub
System.out.println("赵本山小品：卖乖");
}
}
package com.gmail.lsgjzhuwei;
public class Liuqian implements Essayable {
public void essay() {
// TODO Auto-generated method stub
System.out.println("刘谦魔术：水中捞月");
}
}
4.修改主函数中代码
package com.gmail.lsgjzhuwei;
public class EveningParty {
public static void main(String[] args)
{
new EveningParty().process();
}
public void process()
{
//1.晚会开始
//2.唱歌
//3.舞蹈
//4.小品
//5.晚会结束
System.out.println("晚会开始");
//唱歌
Singable singable = new Liudehua();
singable.sing();
//跳舞
Dancleable dancleable = new Xiaohudui();
dancleable.dance();
//小品
// Essayable essayable = new Zhaobenshan();
essayable.essay();
System.out.println("晚会结束");
}
}
但是程序这么写的话会出现一个问题：每次更好演员的时候需要修改晚会类的代码，这就给程序的扩展和维护带来了不便。那应该怎么做呢？可不可以吧这些麻烦的修改部分外包给一个代理去做，由代理类完成演员的修改，这就是我们下面要介绍的一种方法：用Factory类做代理负责代码的修改。
1.在上面程序的基础上新建Factory类，
package com.gmail.lsgjzhuwei;
import java.util.ResourceBundle;
public class Factory {
public Singable getSingable()
{
return new Liudehua();
}
public Dancleable getDancleable()
{
return new Xiaohudui();
}
public static Essayable getEssayable()
{
return new Zhaobenshan();
}
}
package com.gmail.lsgjzhuwei;
public class EveningParty {
public static void main(String[] args)
{
new EveningParty().process();
}
public void process()
{
//1.晚会开始
//2.唱歌
//3.舞蹈
//4.小品
//5.晚会结束
System.out.println("晚会开始");
// //唱歌
// Singable singable = new Liudehua();
// singable.sing();
//
// //跳舞
// Dancleable dancleable = new Xiaohudui();
// dancleable.dance();
//
// //小品
// Essayable essayable = new Zhaobenshan();
// essayable.essay();
Factory factory = new Factory();
factory.getSingable().sing();
factory.getDancleable().dance();
factory.getEssayable().essay();
System.out.println("晚会结束");
}
}
用这种方法不用修改晚会类，但是还是要修改代码，还有一种方法就是将演员的实例类写入配置文件
1.在上面代码的基础上，在src目录下新建party.properties类，将演员的实例类写入配置文件，代码为：
Singable = com.gmail.lsgjzhuwei.Liudehua Dancleable = com.gmail.lsgjzhuwei.Xiaohudui Essayable = com.gmail.lsgjzhuwei.Zhaobenshan2.修改Factory类中调用演员类的代码：
package com.gmail.lsgjzhuwei;
import java.util.ResourceBundle;
public class Factory {
public static Singable getSingable()
{
String className = ResourceBundle.getBundle("party").getString("Singable");
try {
Object obj = Class.forName(className).newInstance();
return (Singable) obj;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
throw new RuntimeException("对象不正确");
}
}
public static Dancleable getDancleable()
{
String className = ResourceBundle.getBundle("party").getString("Dancleable");
try {
Object obj = Class.forName(className).newInstance();
return (Dancleable) obj;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
throw new RuntimeException("对象不正确");
}
}
public static Essayable getEssayable()
{
String className = ResourceBundle.getBundle("party").getString("Essayable");
try {
Object obj = Class.forName(className).newInstance();
return (Essayable) obj;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
throw new RuntimeException("对象不正确");
}
}
}
原文地址：http://blog.csdn.net/longshengguoji/article/details/38795945
