界面设计学习

1、将项目加入到ComboBox的最上面

if ( this .comboBoxWeb.FindStringExact( this .comboBoxWeb.Text)  <   0 )
{
     this .comboBoxWeb.Items.Insert( 0 ,  this .comboBoxWeb.Text);
}

From http://www.codeproject.com/KB/IP/Crawler.aspx

 

2、显示CPU和内存使用率

 代码

System.Diagnostics.PerformanceCounter cpuCounter  =  
     new  System.Diagnostics.PerformanceCounte();
System.Diagnostics.PerformanceCounter ramCounter  =  
     new  System.Diagnostics.PerformanceCounte( " Memory " ,  " Available MBytes " );

cpuCounter.CategoryName  =   " Processor " ;
cpuCounter.CounterName  =   " % Processor Time " ;
cpuCounter.InstanceName  =   " _Total " ;

FreeMemory  =  ramCounter.NextValue();
CPUUsage  =  ( int )cpuCounter.NextValue();

其中FreeMemory和CPUUsage属性定义如下：

代码

private   float  nFreeMemory;
private   float  FreeMemory
{
     get  {  return  nFreeMemory; }
     set  
    {
        nFreeMemory  =  value;
        statusBarPanelMem.Text  =  nFreeMemory  +   " Mb Available " ;
    }
}

private   int  nCPUUsage;
private   int  CPUUsage
{
     get  {  return  nCPUUsage; }
     set  
    {
        nCPUUsage  =  value;
        statusBarPanelCPU.Text  =   " CPU usage "   +  nCPUUsage  +   " % " ;
        Icon icon  =  Icon.FromHandle(((Bitmap)imageListPercentage.Image[value / 10 ]).GetHicon());
        statusBarPanelCPU.Icon  =  icon;
    }
}

而在imageListPercentage中则是十个标识不同进度的图标icon。

From http://www.codeproject.com/KB/IP/Crawler.aspx 

3、监测网络连接状态

代码

[DllImport( " wininet " )]
public   static   extern   int  InternetGetConnectedState( ref   int  lpdwFlags,  int  dwReserved);
[DllImport( " wininet " )]
public   static   extern   int  InternetAutodial( int  dwFlags,  int  hwndParent);

使用下列检测代码：

代码

try
{
     int  nState  =   0 ;
     if (InternetGetConnectedState( ref  nState,  0 )  ==   0 )
    {
         if (nFirstTimeCheckConnection ++   ==   0 )
             //  ask for dial up or DSL connection
             if (InternetAutodial( 1 ,  0 )  !=   0 )
                 //  check internet connection state again
                InternetGetConnectedState( ref  nState,  0 );
    }
     if ((nState  &   2 )  ==   2   ||  (nState  &   4 )  ==   4 )
         //  reset to reask for connection agina
        nFirstTimeCheckConnection  =   0 ;
}
catch
{
}

对其中的状态再进行解析即可：

代码

string  InternetGetConnectedStateString()
{
     string  strState  =   "" ;
     try
    {
         int  nState  =   0 ;
         //  check internet connection state
         if (InternetGetConnectedState( ref  nState,  0 )  ==   0 )
             return   " You are currently not connected to the internet " ;
         if ((nState  &   1 )  ==   1 )
            strState  =   " Modem connection " ;
         else   if ((nState  &   2 )  ==   2 )
            strState  =   " LAN connection " ;
         else   if ((nState  &   4 )  ==   4 )
            strState  =   " Proxy connection " ;
         else   if ((nState  &   8 )  ==   8 )
            strState  =   " Modem is busy with a non-Internet connection " ;
         else   if ((nState  &   0x10 )  ==   0x10 )
            strState  =   " Remote Access Server is installed " ;
         else   if ((nState  &   0x20 )  ==   0x20 )
             return   " Offline " ;
         else   if ((nState  &   0x40 )  ==   0x40 )
             return   " Internet connection is currently configured " ;

         //  get current machine IP
        IPHostEntry he  =  Dns.Resolve(Dns.GetHostName());
        strState  +=   " ,  Machine IP:  " + he.AddressList[ 0 ].ToString();
    }
     catch
    {
    }
     return  strState;
}

注意：字符串中已经包含了当前计算机的IP地址。