浅谈工厂模式

一个简单的计算器例子来描述工厂模式

Operator公共接口

package com.iss.factory;


public interface Operator {
public int getResult(int x, int y);


}

Add.java

package com.iss.factory;


public class Add implements Operator{


@Override
public int getResult(int x, int y) {
// TODO Auto-generated method stub
return x+y;
}


}

Minus.java

package com.iss.factory;


public class Minus implements Operator{


@Override
public int getResult(int x, int y) {
// TODO Auto-generated method stub
return x-y;
}


}

Mul.java

package com.iss.factory;


public class Mul implements Operator{


@Override
public int getResult(int x, int y) {
// TODO Auto-generated method stub
return x*y;
}


}

Divide.java

package com.iss.factory;


public class Divide implements Operator {


@Override
public int getResult(int x, int y) {
// TODO Auto-generated method stub
return x/y;
}


}

OperatorFactory.class

package com.iss.factory;


public class OperatorFactory {
private static Operator operator = null;


public static Operator getOperator(String op) {


if (op == "+") {
operator = new Add();
} else if (op == "-") {
operator = new Minus();
} else if (op == "*") {
operator = new Mul();
} else if (op == "/") {
operator = new Divide();
} else {
return null;
}


return operator;


}


}

Test.java

package com.iss.factory;


public class Test {
public static void main(String[] args) {
Operator operator = OperatorFactory.getOperator("+");
System.out.println(operator.getResult(10, 20));
}


}

总结：工厂模式其实主要利用了面向对象的多态这个特性。程序在实际运行时会有多个选择状态！