简单工厂模式（Simple Factory Pattern)

描述：用一个单独的类来创建实例的过程，这个单独的类成为工厂类，工厂类决定实例化哪个对象！

     


代码：
/**
*
* @author wangdm15@mails.tsinghua.edu.cn:小民
*
*/

//运算抽象类
public abstract class Operation {
public abstract void operation(){
}
}

//加法类
public abstract class Add extends Operation {
public abstract void operation(){
System.out.println("加法");
}
}
//减法类
public abstract class Minuss extends Operation {
public abstract void operation(){
System.out.println("减法");
}
}
//乘法类
public abstract class Multiply extends Operation {
public abstract void operation(){
System.out.println("乘法");
}
}

//工厂类，用于接收一个参数，然后决定构造什么对象
public class OperationFactory {
private Operation operation;
public static Operation createOperation(int type)
{
switch(type){
case 1:
operation=new Add();
break;
case 2:
operation=new Minu();
break;
case 3:
operation=new Multiple();
break;
default:
operation=null;
break;
}
}
}

//用户端
public class Client{
public static void main(String[] args)
{
Operation operation;
operation= OperationFactor.createOperation(1);
//输出加法
operation.operation();
}
}