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

 

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：

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

[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：

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：

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。