查看文件夹大小及占用空间

准备

　　1.簇：要了解文件的大小及占用空间的含义，必须先了解簇的定义。相关信息请看这里。

　　2.GetDiskFreeSpace：获取指定磁盘的信息，包括磁盘的可用空间（Retrieves information about the specified disk, including the amount of free space on the disk）。参考这里。此方法来自 kernel32.dll。具体调用请看正文。

正文

　　1.调用GetDiskFreeSpace获取磁盘信息。

/// <summary>
/// Retrieves information about the specified disk, including the amount of free space on the disk.
/// 获取指定磁盘的信息，包括磁盘的可用空间。
/// </summary>
/// <param name="lpRootPathName">磁盘根目录。如："C:\\"</param>
/// <param name="lpSectorsPerCluster">每个簇所包含的扇区个数</param>
/// <param name="lpBytesPerSector">每个扇区所占的字节数</param>
/// <param name="lpNumberOfFreeClusters">空闲的簇的个数</param>
/// <param name="lpTotalNumberOfClusters">簇的总个数</param>
/// <returns></returns>
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool GetDiskFreeSpace(string lpRootPathName, 
    out uint lpSectorsPerCluster, 
    out uint lpBytesPerSector, 
    out uint lpNumberOfFreeClusters, 
    out uint lpTotalNumberOfClusters);

　　2.获取指定磁盘的簇大小。

public int BytesPerCluster(string drive)
{
    uint lpSectorsPerCluster;
    uint lpBytesPerSector;
    uint lpNumberOfFreeClusters;
    uint lpTotalNumberOfClusters;
    GetDiskFreeSpace(drive, 
        out lpSectorsPerCluster, 
        out lpBytesPerSector, 
        out lpNumberOfFreeClusters, 
        out lpTotalNumberOfClusters);
    return (int)(lpBytesPerSector * lpSectorsPerCluster);
}

　　3.获取文件夹大小及占用空间。

public void DirectoryProperities(string path, int bytesPerCluster, ref long size, ref long usage)
{
    long temp;
    FileInfo fi = null;
    foreach (string file in Directory.GetFiles(path, "*", SearchOption.AllDirectories))
    {
        fi = new FileInfo(file);
        temp = fi.Length;
        size += temp;
        usage += temp + (temp % bytesPerCluster == 0 ? 0 : bytesPerCluster - temp % bytesPerCluster);
    }
}

　　4.剩下的就是除法运算了。

private void Form1_Load(object sender, EventArgs e)
{
    if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
    {
        string path = folderBrowserDialog1.SelectedPath;
        long size = 0, usage = 0;
        DirectoryProperities(path, BytesPerCluster(Path.GetPathRoot(path)), ref size, ref usage);
        lblSize.Text = ((double)size / 1024 / 1024).ToString("0.00 MB") 
            + "(" + size.ToString("N0") + " 字节)";
        lblUsage.Text = ((double)(usage >> 10) / 1024).ToString("0.00 MB") 
            + "(" + usage.ToString("N0") + " 字节)";
    }
}

　　5.大功告成。