策略設計模式

Question

嗨，大家我試圖實現戰略模式，但我不能在具體的類中設置金額，我的意思是金額與助手類中具有關係的金額相同與界面。我嘗試着用構造函數和setter以及getter方法設置這個值，但是如果你可以看一看並給出一些反饋，它就會變成graet.Here就是代碼。

public interface InvoicingAlgorithm 
{ 
    public void getInvoice(String name, double amount); 
} 


public class AmericanInvoice implements InvoicingAlgorithm 
{ 



    AmericanInvoice() 
    { 

    } 
    //Uk: america 1 : 1.57 
    @Override 
    public void getInvoice(String name, double amount) 
    { 
     Customer customer = new Customer(name , amount * 1.57); 
     customer.setAmount(amount * 1.57); 
     customer.getInvoice(); 
    } 

} 

public class Customer 
{ 

    /** 
    * @param name represent the name of the Customer 
    */ 
    private String name; 

    /** 
    * @param amount represent the amount of money 
    */ 
    private double amount; 

    /** 
    * @param i represents object of InvoicingAlgorithm 
    */ 
    private InvoicingAlgorithm i; 

    Customer(String name, double amount) 
    { 
     this.name = name; 
     this.amount = amount; 

    } 

    public String getName() { 
     return name; 
    } 

    public void setName(String name) { 
     this.name = name; 
    } 

    public double getAmount() { 
     return amount; 
    } 

    public void setAmount(double amount) { 
     this.amount = amount; 
    } 

    public InvoicingAlgorithm getI() { 
     return i; 
    } 


    public void setInvoicingAlgorithm(InvoicingAlgorithm i) 
    { 
     this.i = i; 
    } 

    public String getInvoice() 
    { 
     DecimalFormat df = new DecimalFormat("#.00"); 
     String total = "--------------------------------------TO: " 
       + name + "FROM: Easyflap (UK) AMOUNT" + ":$" + 
       df.format(amount) 
       + "--------------------------------------"; 

     return total; 
    } 
} 

所以，當我測試它返回的值--------------------------------- ----- TO：OracleFROM：Easyflap（英國）金額：$ 500.00 ---------------------------------- ----當我嘗試修改AmericanInvoice中的金額時，它來自Customer類中的getInvoice方法，它不起作用。

測試類的AmericanInvoice

public class AmericanInvoiceTest { 

    /** 
    * Test of getInvoice method, of class AmericanInvoice. 
    */ 
    @Test 
    public void testGetInvoice() { 
     System.out.println("Producing American invoice"); 
     final int invoiceAmount = 500; 
     final Customer c = new Customer("Oracle", invoiceAmount); 
     c.setInvoicingAlgorithm(new AmericanInvoice()); 
     String actualOutput = c.getInvoice(); 
     final File f = new File("actual-american.txt"); 
     FileUtility.resetFile(f); 
     FileUtility.writeFile(f, actualOutput); 
     String expectedOutput = FileUtility.readFile(new File("expected-american.txt")); 
     //System.out.println(actualOutput); 
     //System.out.println(expectedOutput); 
     actualOutput = actualOutput.replaceAll("\\s", ""); 
     expectedOutput = expectedOutput.replaceAll("\\s", ""); 
     //System.out.println(actualOutput); 
     //System.out.println(expectedOutput); 
     assertEquals(actualOutput, expectedOutput); 
    } 
} 

Answer 1

其實你不調用策略對象本身上的任何方法！

Answer 2

我不會寬恕這種策略模式，因爲目前的匯率不需要使用Strategy Pattern。但是下面的代碼很可能是你打算根據你的例子做的。

public interface InvoicingAlgorithm { 
    public double adjustInvoice(double amount); 
} 


public class AmericanInvoice implements InvoicingAlgorithm {  
    //Uk: america 1 : 1.57 
    @Override 
    public double adjustInvoice(double amount) { 
     return amount * 1.57; 
    } 
} 

public class Customer { 

    /** 
    * @param name represent the name of the Customer 
    */ 
    private String name; 

    /** 
    * @param amount represent the amount of money 
    */ 
    private double amount; 

    /** 
    * @param i represents object of InvoicingAlgorithm 
    */ 
    private InvoicingAlgorithm i; 

    Customer(String name, double amount) { 
     this.name = name; 
     this.amount = amount; 

    } 

    public String getName() { 
     return name; 
    } 

    public void setName(String name) { 
     this.name = name; 
    } 

    public double getAmount() { 
     return amount; 
    } 

    public void setAmount(double amount) { 
     this.amount = amount; 
    } 

    public InvoicingAlgorithm getI() { 
     return i; 
    } 

    public void setInvoicingAlgorithm(InvoicingAlgorithm i) { 
     this.i = i; 
    } 

    public String getInvoice() { 
     DecimalFormat df = new DecimalFormat("#.00"); 
     String total = "--------------------------------------TO: " 
       + name + "FROM: Easyflap (UK) AMOUNT" + ":$" + 
       df.format(i.adjustInvoice(amount)) 
       + "--------------------------------------"; 

     return total; 
    } 
}