Delen via

COM Interop-voorbeeld: .NET-client en COM-server

In dit voorbeeld ziet u hoe een .NET-client die is gebouwd voor toegang tot een COM-server, een exemplaar van een COM-coklasse maakt en klasseleden aanroept om hypotheekberekeningen uit te voeren.

In dit voorbeeld maakt en roept de client een exemplaar van de Loan coklasse aan, geeft vier argumenten (een van deze vier gelijk aan nul) door aan het exemplaar en worden de berekeningen weergegeven. Codefragmenten uit dit voorbeeld worden in deze sectie weergegeven.

.NET-client

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-server

// 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;
}

Zie ook

  • Last updated on