java简单工程模式

实现一个计算器

1.新建计算类

  
public class Operation {
	private double _numa;
	private double _numb;
	private double _result;

	/**
	 * 获取_numa
	 * 
	 * @return _numa
	 */

	public double get_numa() {
		return _numa;
	}

	/**
	 * 设置_numa
	 * 
	 * @param _numa
	 */
	public void set_numa(double _numa) {
		this._numa = _numa;
	}

	/**
	 * 获取_numb
	 * 
	 * @return _numb
	 */

	public double get_numb() {
		return _numb;
	}

	/**
	 * 设置_numb
	 * 
	 * @param _numb
	 */
	public void set_numb(double _numb) {
		this._numb = _numb;
	}

	/**
	 * 获取_result
	 * 
	 * @return _result
	 */

	public double get_result() {
		return _result;
	}

	/**
	 * 设置_result
	 * 
	 * @param _result
	 */
	public void set_result(double _result) {
		this._result = _result;
	}
}

2.新建一个加法类继承OpetationAdd并重写get_result()方法

  
public class OperationFactory {
	/**
	 * 创建运算类
	 */
	public static Operation createOperation(String operator) {
		Operation operation = null;
		switch (operator) {
		case "+":
			operation = new OperationAdd();
			break;

		default:
			break;
		}
		return operation;
	}

	/**
	 * 描述方法的作用
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		Operation op = new OperationFactory().createOperation("+");
		op.set_numa(2);
		op.set_numb(2);
		System.out.println(op.get_result());
	}

}
3.新建OperationFactory类并新建createOperation()方法实现抽象运算

  
public class OperationFactory {
	/**
	 * 创建运算类
	 */
	public static Operation createOperation(String operator) {
		Operation operation = null;
		switch (operator) {
		case "+":
			operation = new OperationAdd();
			break;

		default:
			break;
		}
		return operation;
	}

	

}
4.测试运行加法

  
/**
	 * 描述方法的作用
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		Operation op = new OperationFactory().createOperation("+");
		op.set_numa(2);
		op.set_numb(2);
		System.out.println(op.get_result());
	}
以后需要修改加法只要修改OperationAdd类即可

如果需要添加其他复杂运算,只要添加相关类并在OperationFactory类的createOperation()方法中添加switch分支即可