C#设计软件30天评估期限制

为了保护软件的著作权，又想让用户有个好的体验，我们需要设计软件评估期，这里贴一个用C#实现软件评估期30天的限制的实例代码：

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Text; 
using System.Windows.Forms; 
using Infralution.Licensing.CF; 

namespace Geoff.DeviceApplication 
{ 
    public partial class Form1 : Form 
    { 
        const string LICENSE_PARAMETERS = 
            @"<LicenseParameters> 
                <RSAKeyValue> 
                    <Modulus>rzRJ6dZ4ZTJ8/EzFtq2XIaik7QBSc24b8i8KJrPaxXGiCMDFcj8JtEFePa1SYX1W3cQoiwvCAF/MYmkXto74WdApYzILel+bOHSaUXTImrxpPtykNhPD7fF3PEXxrLRrTjUWQyEX5+XSaNPstmbDJw/Zg83mraCfmGeLcsiEypM=</Modulus> 
                    <Exponent>AQAB</Exponent> 
                </RSAKeyValue> 
                <DesignSignature>GJYsK2rQE7uj539+QCyJ3Z2GyrNEZQNxruxOQR6P2jo+Ze3Ev5Kgbf3N33RaLf7oEUsZNF4Gv7w5UFgYcdHzCphqznt4vcR++u9tb0sC5m6hf26538GXhkNodyVR9FDcv1AX4+PaM/kY+Z8mrMMmC148lYPpCHypXvgjOmDd9oQ=</DesignSignature> 
                <RuntimeSignature>coZIUnOTaRZCIa67HBMM6/xbkQNYS+l4ROeLmzn7SqRamBwP7cbfOEAsxlFV2roKlY6oz1B91/PYcTVPLfWahwjHaiAaLjKAosXK41yZOozu0vRWpv4H9ERiEli0pYX0M8fMBIkvSDT6n9X9T/6U4ujyefv8b4IxbYsB3zsjjx0=</RuntimeSignature> 
                <KeyStrength>7</KeyStrength> 
             </LicenseParameters>"; 

        const string LICENSE_FILE = "Licensed.lic"; 

        public Form1() 
        { 
            InitializeComponent(); 

            EncryptedLicenseProvider provider = new EncryptedLicenseProvider(); 
            EncryptedLicense license = provider.GetLicense(LICENSE_PARAMETERS, LICENSE_FILE); 
            if (license == null) 
            { 
                LicenseInstallForm licenseForm = new LicenseInstallForm(); 

                license = licenseForm.ShowDialog("DeviceApp", LICENSE_FILE); 
                if (license != null) 
                { 
                    MessageBox.Show("程式授权"); 
                } 
            } 

            if (license == null) 
            { 
                EvaluationMonitor monitor = new EvaluationMonitor("DeviceApp"); 
                if (monitor.DaysInUse > 30 || monitor.Invalid) 
                { 
                    MessageBox.Show("程式评估期限过期"); 
                    Application.Exit(); 
                } 
                else 
                { 
                    MessageBox.Show(string.Format("程式30天评估期，已使用{0}天", monitor.DaysInUse));  
                } 
            } 
        } 
    } 
}