设计模式之用工厂模式实现计算器

1.用简单工厂模式实现计算器

相当于抽象product类
public abstract class Operation {
    private double num1;
    private double num2;
    public double getNum1() {
        return num1;
    }
    public void setNum1(double num1) {
        this.num1 = num1;
    }
    public double getNum2() {
        return num2;
    }
    public void setNum2(double num2) {
        this.num2 = num2;
    }
    public abstract double getResult();
}
具体产品类：
public class AddOperation extends Operation{
    @Override
    public double getResult() {
        // TODO Auto-generated method stub
        double  result = this.getNum1() + this.getNum2();
        return result;
    }    
}

public class SubOperation extends Operation{
    @Override
    public double getResult() {
        // TODO Auto-generated method stub
        double result = this.getNum1() - this.getNum2();
        return result;
    }
}
//工厂类：
public class OperationFactory {
      public static Operation getOperation(String oper){
          Operation operation = null;
          if("+".equals(oper)){
             operation = new AddOperation();
          }
          if("-".equals(oper)){
              operation = new SubOperation();
          }
        return operation;
      }
}

测试：
public class MainClass {
     public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入数字1：");
        String num1 = scanner.nextLine();
        System.out.println("请输入操作符：");
        String oper = scanner.nextLine();
        System.out.println("请输入数字2：");
        String num2 = scanner.nextLine();
        
        Operation operation = OperationFactory.getOperation(oper);
        operation.setNum1(Double.parseDouble(num1));
        operation.setNum2(Double.parseDouble(num2));
        double result = operation.getResult();
        System.out.println(result);
    }
}

2.用工厂方法模式实现：

相当于抽象product类
public abstract class Operation {
    private double num1;
    private double num2;
    public double getNum1() {
        return num1;
    }
    public void setNum1(double num1) {
        this.num1 = num1;
    }
    public double getNum2() {
        return num2;
    }
    public void setNum2(double num2) {
        this.num2 = num2;
    }
    public abstract double getResult();
}
具体产品类：
public class AddOperation extends Operation{
    @Override
    public double getResult() {
        // TODO Auto-generated method stub
        double  result = this.getNum1() + this.getNum2();
        return result;
    }    
}

public class SubOperation extends Operation{
    @Override
    public double getResult() {
        // TODO Auto-generated method stub
        double result = this.getNum1() - this.getNum2();
        return result;
    }
}

工厂：
public interface OperationFactoryMethod {
      public Operation getOperation();
}
实现类（创建对象）：
public class AddOperationFactory implements OperationFactoryMethod{
    @Override
    public Operation getOperation() {
        // TODO Auto-generated method stub
        return new AddOperation();
    }  
}

public class SubOperationFactory implements OperationFactoryMethod{
    @Override
    public Operation getOperation() {
        // TODO Auto-generated method stub
        return new SubOperation();
    }
}

测试：
public class MainClass {
     public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入数字1：");
        String num1 = scanner.nextLine();
        System.out.println("请输入操作符：");
        String oper = scanner.nextLine();
        System.out.println("请输入数字2：");
        String num2 = scanner.nextLine();
        double result = 0;
        if("+".equals(oper)){
            Operation operation = new AddOperationFactory().getOperation();
            operation.setNum1(Double.parseDouble(num1));
            operation.setNum2(Double.parseDouble(num2));
            result = operation.getResult();
        }
       if("-".equals(oper)){
           Operation operation = new SubOperationFactory().getOperation();
           operation.setNum1(Double.parseDouble(num1));
           operation.setNum2(Double.parseDouble(num2));
           result = operation.getResult();
       }
        System.out.println(result);
    }
}

运行结果：