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COM Birlikte Çalışma Örneği: .NET İstemcisi ve COM Sunucusu

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Bu örnek, COM sunucusuna erişmek için oluşturulmuş bir .NET istemcisinin bir COM coclass örneğini nasıl oluşturduğunu ve ipotek hesaplamaları yapmak için sınıf üyelerini nasıl çağırduğunu gösterir.

Bu örnekte istemci, Loan ortak sınıfının bir örneğini oluşturur ve çağırır, örneğe dört bağımsız değişken (bu dört bağımsız değişkenden biri sıfıra eşit) geçirir ve hesaplamaları görüntüler. Bu örnekteki kod parçaları bu bölümün her yanında görünür.

.NET İstemcisi

Imports System  
Imports Microsoft.VisualBasic  
Imports LoanLib  
  
Public Class LoanApp  
  
    Public Shared Sub Main()  
        Dim Args As String()  
        Args = System.Environment.GetCommandLineArgs()  
  
        Dim ln As New Loan()  
  
        If Args.Length < 5 Then  
            Console.WriteLine("Usage: ConLoan Balance Rate Term Payment")  
            Console.WriteLine(" Either Balance, Rate, Term, or Payment " _  
                                & "must be 0")  
            Exit Sub  
        End If  
  
        ln.OpeningBalance = Convert.ToDouble(Args(1))  
        ln.Rate = Convert.ToDouble(Args(2)) / 100.0  
        ln.Term = Convert.ToInt16(Args(3))  
        ln.Payment = Convert.ToDouble(Args(4))  
  
        If ln.OpeningBalance = 0.0 Then  
            ln.ComputeOpeningBalance()  
        End If  
        If ln.Rate = 0.0 Then  
            ln.ComputeRate()  
        End If  
        If ln.Term = 0 Then  
            ln.ComputeTerm()  
        End If  
        If ln.Payment = 0.0 Then  
            ln.ComputePayment()  
        End If
        Console.WriteLine("Balance = {0,10:0.00}", ln.OpeningBalance)  
        Console.WriteLine("Rate    = {0,10:0.0%}", ln.Rate)  
        Console.WriteLine("Term    = {0,10:0.00}", ln.Term)  
        Console.WriteLine("Payment = {0,10:0.00}" & ControlChars.Cr, _  
                          ln.Payment)  
  
        Dim MorePmts As Boolean  
        Dim Balance As Double = 0.0  
        Dim Principal As Double = 0.0  
        Dim Interest As Double = 0.0  
  
        Console.WriteLine("{0,4}{1,10}{2,12}{3,10}{4,12}", _  
           "Nbr", "Payment", "Principal", "Interest", "Balance")  
        Console.WriteLine("{0,4}{1,10}{2,12}{3,10}{4,12}", _  
           "---", "-------", "---------", "--------", "-------")  
  
        MorePmts = ln.GetFirstPmtDistribution(ln.Payment, Balance, _  
           Principal, Interest)  
  
        Dim PmtNbr As Short  
  
        While MorePmts  
  
            Console.WriteLine("{0,4}{1,10:0.00}{2,12:0.00}{3,10:0.00}" _  
              & "{4,12:0.00}", PmtNbr, ln.Payment, Principal, Interest,  
              Balance)  
            MorePmts = ln.GetNextPmtDistribution(ln.Payment, Balance, _  
              Principal, Interest)  
            PmtNbr += CShort(1)  
        End While  
    End Sub  
End Class  

using System;  
using LoanLib;  
  
public class LoanApp {  
   public static void Main(String[] Args) {  
  
      Loan ln = new Loan();  
  
      if (Args.Length < 4)
      {  
         Console.WriteLine("Usage: ConLoan Balance Rate Term Payment");  
         Console.WriteLine("    Either Balance, Rate, Term, or Payment
            must be 0");  
         return;  
      }  
  
      ln.OpeningBalance = Convert.ToDouble(Args[0]);  
      ln.Rate = Convert.ToDouble(Args[1])/100.0;  
      ln.Term = Convert.ToInt16(Args[2]);  
      ln.Payment = Convert.ToDouble(Args[3]);  
  
      if (ln.OpeningBalance == 0.00) ln.ComputeOpeningBalance();  
      if (ln.Rate == 0.00) ln.ComputeRate();  
      if (ln.Term == 0) ln.ComputeTerm();  
      if (ln.Payment == 0.00) ln.ComputePayment();  
  
      Console.WriteLine("Balance = {0,10:0.00}", ln.OpeningBalance);  
      Console.WriteLine("Rate    = {0,10:0.0%}", ln.Rate);  
      Console.WriteLine("Term    = {0,10:0.00}", ln.Term);  
      Console.WriteLine("Payment = {0,10:0.00}\n", ln.Payment);  
  
      bool MorePmts;  
      double Balance = 0.0;  
      double Principal = 0.0;  
      double Interest = 0.0;  
  
      Console.WriteLine("{0,4}{1,10}{2,12}{3,10}{4,12}", "Nbr", "Payment",  
        "Principal", "Interest", "Balance");  
      Console.WriteLine("{0,4}{1,10}{2,12}{3,10}{4,12}", "---", "-------",  
        "---------", "--------", "-------");  
  
      MorePmts = ln.GetFirstPmtDistribution(ln.Payment, out Balance,
        out Principal, out Interest);  
  
      for (short PmtNbr = 1; MorePmts; PmtNbr++) {  
         Console.WriteLine("{0,4}{1,10:0.00}{2,12:0.00}{3,10:0.00}  
           {4,12:0.00}", PmtNbr, ln.Payment, Principal, Interest,  
            Balance);  
         MorePmts = ln.GetNextPmtDistribution(ln.Payment, ref Balance,
           out Principal, out Interest);
      }  
    }  
}

COM Sunucusu

// Loan.cpp : Implementation of CLoan  
#include "stdafx.h"  
#include "math.h"  
#include "LoanLib.h"  
#include "Loan.h"  
  
static double Round(double value, short digits);
  
STDMETHODIMP CLoan::get_OpeningBalance(double *pVal)  
{  
    *pVal = OpeningBalance;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::put_OpeningBalance(double newVal)  
{  
    OpeningBalance = newVal;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::get_Rate(double *pVal)  
{  
    *pVal = Rate;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::put_Rate(double newVal)  
{  
    Rate = newVal;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::get_Payment(double *pVal)  
{  
    *pVal = Payment;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::put_Payment(double newVal)  
{  
    Payment = newVal;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::get_Term(short *pVal)  
{  
    *pVal = Term;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::put_Term(short newVal)  
{  
    Term = newVal;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::ComputePayment(double *pVal)  
{  
    Payment = Round(OpeningBalance * (Rate /
        (1 - pow((1 + Rate), -Term))),2);  
    *pVal = Payment;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::ComputeOpeningBalance(double *pVal)  
{  
    OpeningBalance = Round(Payment / (Rate /
        (1 - pow((1 + Rate), -Term))),2);  
    *pVal = OpeningBalance ;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::ComputeRate(double *pVal)  
{  
    double DesiredPayment = Payment;  
  
    for (Rate = 0.001; Rate < 28.0; Rate += 0.001)  
    {  
        Payment = Round(OpeningBalance * (Rate /
         (1 - pow((1 + Rate), -Term))),2);  
  
        if (Payment >= DesiredPayment)  
            break;  
    }  
  
    *pVal = Rate;
    return S_OK;  
}  
  
STDMETHODIMP CLoan::ComputeTerm(short *pVal)  
{  
    double DesiredPayment = Payment;  
    for (Term = 1; Term < 480 ; Term ++)  
    {  
        Payment = Round(OpeningBalance * (Rate /
         (1 - pow((1 + Rate), -Term))),2);  
        if (Payment <= DesiredPayment)  
            break;  
    }  
    *pVal = Term;
    return S_OK;  
}  
  
STDMETHODIMP CLoan::GetFirstPmtDistribution(double PmtAmt, double *Balance, double *PrinPortion, double *IntPortion, VARIANT_BOOL *pVal)  
{  
    *Balance = OpeningBalance;  
    GetNextPmtDistribution(PmtAmt, Balance, PrinPortion, IntPortion,
      pVal);  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::GetNextPmtDistribution(double PmtAmt, double *Balance, double *PrinPortion, double *IntPortion, VARIANT_BOOL *pVal)  
{  
    *IntPortion = Round(*Balance * Rate, 2);  
    *PrinPortion = Round(PmtAmt - *IntPortion, 2);  
    *Balance = Round(*Balance - *PrinPortion, 2);  
  
    if (*Balance <= 0.0)  
        *pVal = FALSE;  
    else  
        *pVal = TRUE;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::get_RiskRating(BSTR *pVal)  
{  
    *pVal = (BSTR)RiskRating;  
    return S_OK;  
}  
  
STDMETHODIMP CLoan::put_RiskRating(BSTR newVal)  
{  
    RiskRating = newVal;  
    return S_OK;  
}  
static double Round(double value, short digits)
{  
    double factor = pow(10, digits);  
    return floor(value * factor + 0.5)/factor;  
}

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