前言:
这是我学习的第二个模式,感觉学了模式编程越来越有趣了!
策略模式:
定义了算法家族,分别封装起来,让他们可以相互替换,此模式让算法的变换,不影响到使用算法的客户。
策略模式的结构图:
策略模式通过定义一个Context类,通过这个类进行具体的算法替换,使得具体的算法依赖Context的接口,通过它来决定具体使用哪个算法。
namespace 策略模式
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
abstract class CashSuper //定义CashSuper抽象类,设置抽象方法 acceptCash
{
public abstract double acceptCash(double money);
}
class CashContext //定义策略类CashContext
{
private CashSuper cs;
public CashSuper(CashSuper csuper)
{
this.cs = csuper;
}
public double GetResult(double money)
{
return cs.acceptCash(money);//生成相应的类
}
}
class CashNormal : CashSuper //原价类
{
public override double acceptCash(double money)
{
return money;
}
}
class CashRebate : CashSuper // 打折类
{
public double moneyRebate = 1d;
public CashRebate(string moneyRebate)
{
this.moneyRebate = double.Parse(moneyRebate);
}
public override double acceptCash(double money)
{
return money * moneyRebate;
}
}
class CashReturn : CashSuper //返现金类
{
private double moneyCondition = 0.0d;
private double moneyReturn = 0.0d;
public CashReturn(string moneyCondition, String moneyReturn)
{
this.moneyCondition = double.Parse(moneyCondition);
this.moneyReturn = double.Parse(moneyReturn);
}
public override double acceptCash(double money)
{
double result = money;
if (money>=moneyCondition)
result = money - Math.Floor(money / moneyCondition) * moneyReturn;
return result;
}
class CashFactory
{
public static CashSuper createCashAccept(string type)
{
CashSuper cs = null;
switch (type)
{
case "正常收费":
cs = new CashNormal();
break;
case "满300-100":
//CashReturn cr1 = new CashReturn("300", "100");
//cs = cr1;
cs= new CashReturn("300", "100");
break;
case"打八折":
//CashRebate cr2=new CashRebate("0.8");j
//cs = cr2;
cs = new CashRebate("0.8");
break;
}
return cs;
}
}
}
private void button_Click(object sender, RoutedEventArgs e)
{
CashContext cc = null;
switch (comboBox.SelectedItem.ToString())
{
case "正常收费":
cc = new CashContext(new CashNormal());
break;
case "满三百,返一百":
cc = new CashContext(new CashReturn("300", "100"));
break;
case "打八折":
cc = new CashContext(new CashRebate("0.8"));
break;
}
double total = 0.0d;
double totalPrices = cc.GetResult (Convert.ToDouble(txtPrice.Text) * Convert.ToDouble(txtNum.Text));
total = total + totalPrices;
lbxList.Items.Add("单价" + txtPrice.Text + "数量" + txtNum.Text + "合计" + totalPrices.ToString());
result.Content= total.ToString();
}
}
}
我们通过写相应的算法:打折,原价,满减 这三个子类,同时在创建一个抽象策略CashSuper,然后在客户端进行判断需要哪个算法通过CashContext 这个类进行实际算法的转换就行了。
应用场景:
1.针对同一类型问题的多种处理方式,仅仅是具体行为有差别时;
2.需要安全地封装多种同一类型的操作时;
3.出现同一抽象类有多个子类,而又需要来选择具体子类时。
总结:
策略模式方便我们管理相关的算法和减少选择判断语句,但是如果策略过多那我们需要写的算法也就很客观,并且前提是我们可以正确的使用我们的策略,总的来说策略模式还是更有利于我们开发