大话设计模式--计算器

作为一名程序员，必要的总结是不可以缺少的。计划从现在开始到明年年底将《大话设计模式》这本书中所列举的设计模式都纪录一遍用于以后工作的提升！

简单工厂之计算器

写这个功能之前，我需要整理一下写代码的基本思路：写程序必须要以能复用，易于维护为原则，一定要使用面向对象的三大特征封装继承和多态。引用《大话设计模式》中的一个例子在活字印刷出来之前，印刷的模板都是一次性使用的，因此一本书的成本太高，这样大规模使用是很难实现的。如果放到当今这个以流量为王的时代绝对会被淘汰。代码

public class Operation
```
{
```
```
    private double _numbA = 0;
```
```
    private double _numbB = 0;
```
```
    public double _NumbA
```
```
    {
```
```
        get
```
```
        {
```
```
            return _numbA;
```
```
        }
```
```
        set
```
```
        {
```
```
            _numbA = value;
```
```
        }
```
```
    }
```
```
    public double _NumbB
```
```
    {
```
```
        get
```
```
        {
```
```
            return _numbB;
```
```
        }
```
```
        set
```
```
        {
```
```
            _numbB = value;
```
```
        }
```
```
    }
```
```
    public virtual double getResult()
```
```
    {
```
```
        double result = 0;
```
```
        return result;
```
```
    }
```
```
}
```

//上边是抽象出来其他运算类需要继承的父类。

//下边写具体实现
//加法类

public class OperationAdd : Operation
```
{
```
```
    public override double getResult()
```
```
    {
```
```
        double result = 0;
```
```
        result = _NumbA + _NumbB;
```
```
        return result;
```
```
    }
```
```
}
```

//减法类

public class OperationSub : Operation
```
{
```
```
    public override double getResult()
```
```
    {
```
```
        double result = 0;
```
```
        result = _NumbA - _NumbB;
```
```
        return result;
```
```
    }
```
```
}
```

//乘法类

public class OperationMulti : Operation
```
{
```
```
    public override double getResult()
```
```
    {
```
```
        double result = 0;
```
```
        result = _NumbA * _NumbB;
```
```
        return result;
```
```
    }
```
```
}
```

//除法类

public class OperationDivde : Operation
```
{
```
```
    public override double getResult()
```
```
    {
```
```
        double result = 0;
```
```
        if (_NumbB == 0)
```
```
        {
```

            throw new Exception("除数不能为零！！");

```
        }
```
```
        result = _NumbA / _NumbB;
```
```
        return result;
```
```
    }
```
```
}
```

//后台类已经写好了，前台控制台程序也好，webform程序也好都可以使用。我是以asp.net webform配合ajax来实现的。 //前台数据通过ajax传递到后台一般处理性程序(ashx)文件，数据处理后将数据传递到前台。 //在这里需要添加一个ashx类的父类，通过反射的方式简化调用程序。

public class Parent : IHttpHandler
```
{
```
```
    private string m_flag;
```
```
    public string Flag
```
```
    {
```
```
        get { return m_flag; }
```
```
        set { m_flag = value; }
```
```
    }
```

    public void ProcessRequest(HttpContext context)

```
    {
```

        if (context.Request["flag"] != null)

            m_flag = context.Request["flag"].ToString();

        var methodName = context.Request["flag"];

```
        Type objType = this.GetType();
```

        MethodInfo method = objType.GetMethod(methodName == null ? "" : methodName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);

```
        if (method != null)
```
```
        {
```

            HttpContext[] objParams = new HttpContext[] { context };

            method.Invoke(this, objParams);

```
        }
```
```
        else
```
```
        {
```
```
            Other(context);
```
```
        }
```
```
    }
```

    public virtual void Other(HttpContext context)

```
    {
```
```
    }
```
```
    public bool IsReusable
```
```
    {
```
```
        get
```
```
        {
```
```
            return false;
```
```
        }
```
```
    }
```
```
}
```

//创建调用类，调用类中的代码

public class Caculate : Parent
```
{
```

    public void NumOperate(HttpContext context)

```
    {
```

        var expression = context.Request["expression"];//这里是将用户的表达式获取过来

        var operateFlag = context.Request["operateFlag"].ToCharArray();

        var ExpreArry = expression.Split(operateFlag);//然后通过用户输入的运算符来分割

```
        Operation operate = null;
```
```
        switch (operateFlag[0])
```
```
        {
```
```
            case '+':
```

                operate = new OperationAdd();

```
                break;
```
```
            case '-':
```

                operate = new OperationSub();

```
                break;
```
```
            case '*':
```

                operate = new OperationMulti();

```
                break;
```
```
            case '/':
```

                operate = new OperationDivde();

```
                break;
```
```
        }
```

        operate._NumbA = Convert.ToDouble(ExpreArry[0]);//不论是加减乘除都可以使用同一种方式来调用

        operate._NumbB = Convert.ToDouble(ExpreArry[1]);

        var result = operate.getResult();

        context.Response.Write(result);

```
        context.Response.End();
```
```
    }
```
```
}
```

//后台调用完毕，下边开始写前台调用方式。首先需要引用jQuery文件，然后就可以使用jQuery中的方法了。在这里不展示引用(太简单)

//前台HTML布局使用的是table布局

<body>
```
<table id="caclator">
```
```
    <tr>
```
```
        <td colspan="5">
```

            <input type="text" id="txtExpression" />

```
        </td>
```
```
    </tr>
```
```
    <tr>
```
```
        <td>
```

            <input type="button" value="MC" id="btnMC" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="MR" id="btnMR" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="MS" id="btnMS" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="M+" id="btnMAdd" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="M-" id="btnMSub" />

```
        </td>
```
```
    </tr>
```
```
    <tr>
```
```
        <td>
```

            <input type="button" value="←" id="btnBackSpace" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="CE" id="btnCE" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="C" id="btnC" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="±" id="Button4" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="√" id="Button5" />

```
        </td>
```
```
    </tr>
```
```
    <tr>
```
```
        <td>
```

            <input type="button" value="7" id="btnNumSeven" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="8" id="btnNumEight" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="9" id="btnNumNine" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="/" id="btnOperDivide" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="%" id="Button10" />

```
        </td>
```
```
    </tr>
```
```
    <tr>
```
```
        <td>
```

            <input type="button" value="4" id="btnNumFour" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="5" id="btnNumFive" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="6" id="btnNumSix" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="*" id="btnOperMulti" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="1/x" id="Button12" />

```
        </td>
```
```
    </tr>
```
```
    <tr>
```
```
        <td>
```

            <input type="button" value="1" id="btnNumOne" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="2" id="btnNumTwo" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="3" id="btnNumThree" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="-" id="btnOperSub" />

```
        </td>
```
```
        <td rowspan="2">
```

            <input type="button" value="=" id="btnEques" />

```
        </td>
```
```
    </tr>
```
```
    <tr>
```
```
        <td colspan="2">
```

            <input type="button" value="0" id="btnNumZero" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="." id="btnPoint" />

```
        </td>
```
```
        <td>
```

            <input type="button" value="+" id="btnOperAdd" />

```
        </td>
```
```
    </tr>
```
```
</table>
```
</body>

//仅仅实现了+-*/最基本的算法，因此没有涉及到的按钮id名称就没修改
//以下是css样式设置

<style type="text/css">
```
    input[type='button']
```
```
    {
```
```
        height: 25px;
```
```
        width: 35px;
```
```
    }
```
```
    input[type='button'][value='0']
```
```
    {
```
```
        height: 25px;
```
```
        width: 72px;
```
```
    }
```
```
    input[type='button'][value='=']
```
```
    {
```
```
        height: 52px;
```
```
        width: 35px;
```
```
    }
```
```
    input[type='text']
```
```
    {
```
```
        width: 185px;
```
```
    }
```
```
</style>
```

//运行图仿照win7中计算器样式
大话设计模式--计算器-LMLPHP
//最后添加jQuery代码

<script type="text/javascript">

var expression = ""; //存放用户表达式

var operateFlag = ""; //存放用户操作 +-*/

```
$(function () {
```
```
    $("#txtExpression").val('');
```

    $("#caclator").offset({ top: 300, left: 900 });

    $.each($("input"), function (i, j) {

        if (j.id.indexOf("Num") > -1) {

            $("#" + j.id).click(function () {

                expression += this.value;

                $("#txtExpression").val(expression);

```
            })
```
```
        }
```
```
    })
```

    $.each($("input"), function (i, j) {

        if (j.id.indexOf("Oper") > -1) {

            $("#" + j.id).click(function () {

                expression += this.value;

                $("#txtExpression").val(expression);

                if (this.value != ".") {

```
                    operateFlag = "";
```

                    operateFlag = this.value;

```
                }
```
```
            })
```
```
        }
```
```
    })
```
```
    $("#btnEques").click(function () {
```

        var url = "/Handler/Caculate.ashx?t=" + new Date();

```
        $.ajax({
```
```
            type: "POST",
```
```
            url: url,
```

            data: { flag: "NumOperate", expression: expression, operateFlag: operateFlag },

```
            async: false,
```
```
            cache: false,
```
```
            success: function (msg) {
```
```
                expression = "";
```

                $("#txtExpression").val(msg);

```
            },
```
```
            error: function (msg) {
```

                if (msg.status == 500) {

                    alert("错误，不允许的操作！");//如果除数为0，那么就会弹出提示信息

```
                }
```
```
            }
```
```
        })
```
```
    })
```
```
})
```
</script>

刘怀日

大话设计模式--计算器