java设计模式——简单工厂模式

《大话设计模式》第一章

package ch01;

public abstract class Operation {
	private double numberA = 0;
	private double numberB = 0;
	public double getNumberA() {
		return numberA;
	}
	public void setNumberA(double numberA) {
		this.numberA = numberA;
	}
	public double getNumberB() {
		return numberB;
	}
	public void setNumberB(double numberB) {
		this.numberB = numberB;
	}
	
	public abstract double getResult() throws Exception;
}

package ch01;

public class OperationAdd extends Operation {

	@Override
	public double getResult() throws Exception {
		return getNumberA() + getNumberB();
	}

}

package ch01;

public class OperationDiv extends Operation {

	@Override
	public double getResult() throws Exception {
		return getNumberA() / getNumberB();
	}

}

package ch01;

public class OperationMul extends Operation {

	@Override
	public double getResult() throws Exception {
		return getNumberA() * getNumberB();
	}

}

package ch01;

public class OperationSub extends Operation {

	@Override
	public double getResult() throws Exception {
		return getNumberA() - getNumberB();
	}

}

package ch01;

public class OperationFactory {
	public static Operation createOperation(String operate) {
		Operation oper = null;
		if ("+".equals(operate)) {
			oper = new OperationAdd();
		} else if ("-".equals(operate)) {
			oper = new OperationSub();
		} else if ("*".equals(operate)) {
			oper = new OperationMul();
		} else if ("/".equals(operate)) {
			oper = new OperationDiv();
		}
		
		return oper;
	}
}

package ch01;

/**
 * 简单工厂模式
 * @author Administrator
 *
 */
public class Client {

	/**
	 * @param args
	 * @throws Exception 
	 */
	public static void main(String[] args) throws Exception {
		Operation oper = OperationFactory.createOperation("+");
		oper.setNumberA(3.0);
		oper.setNumberB(4.0);
		System.out.println(oper.getResult());
	}

}

这个不需要什么解释，代码应该很好理解。