设计模式 之 策略模式

/**
 * 操作接口
 * @author GaoYuan
 * @date 2018/11/11 下午2:45
 */
public interface IOperation {
    /** 执行计算 */
    int operation(int a,int b);

}

/**
 * 加法
 */
public class AddOperation implements IOperation{

    @Override
    public int operation(int a, int b) {
        return a + b;
    }
}
/**
 * 减法
 */
public class SubOperation implements IOperation{

    @Override
    public int operation(int a, int b) {
        return a - b;
    }
}
/**
 * 乘法
 */
public class MulOperation implements IOperation{

    @Override
    public int operation(int a, int b) {
        return a * b;
    }

}
/**
 * 除法
 */
public class DivOperation implements IOperation{

    @Override
    public int operation(int a, int b){
        if(b == 0){
            return 0;
        }
        return a / b;
    }
    
}

/**
 * 使用者
 * @author GaoYuan
 * @date 2018/11/11 下午2:51
 */
public class Context {

    IOperation iOperation;

    public Context(IOperation iOperation) {
        this.iOperation = iOperation;
    }

    public int execute(int a, int b){
        return iOperation.operation(a, b);
    }
}

public static void main(String[] args){
    // 加
    Context context = new Context(new AddOperation());
    System.out.println(context.execute(6,2));
    // 减
    context = new Context(new SubOperation());
    System.out.println(context.execute(6,2));
    // 乘
    context = new Context(new MulOperation());
    System.out.println(context.execute(6,2));
    // 除
    context = new Context(new DivOperation());
    System.out.println(context.execute(6,2));
}

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