Compartir a través de

Ejemplo de interoperabilidad COM: cliente .NET y servidor COM

En este ejemplo se muestra cómo un cliente .NET, creado para acceder a un servidor COM, crea una instancia de una coclase COM y llama a miembros de clase para realizar cálculos de hipotecas.

En este ejemplo, el cliente crea y llama a una instancia de la Loan coclase, pasa cuatro argumentos (uno de esos cuatro que son iguales a cero) a la instancia y muestra los cálculos. Los fragmentos de código de este ejemplo aparecen en esta sección.

Cliente de .NET

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);
      }
    }
}

Servidor COM

// 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;
}

Consulte también

  • Last updated on