C#访问网络共享文件夹的方法

C#访问网络共享文件夹的方法有以下两种：

1. 使用.NET框架提供的System.IO命名空间和File类
2. 使用WNetAddConnection2函数和WNetCancelConnection2函数

方法一：使用System.IO命名空间和File类

在C#中，我们可以使用System.IO命名空间中的File类来访问网络共享文件夹。具体步骤如下：

1. 在代码中引入System.IO命名空间.

using System.IO;

1. 使用File的静态方法来打开文件

FileStream fileStream = File.Open(@"\\servername\sharedfolder\file.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

需要注意的是，在文件路径中要指定网络共享文件夹的地址，格式为\servername\sharedfolder\filename。

代码示例：

using System.IO;

namespace AccessNetworkSharedFolder
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                FileStream fileStream = File.Open(@"\\servername\sharedfolder\file.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                StreamReader reader = new StreamReader(fileStream);
                Console.WriteLine(reader.ReadLine());
                reader.Close();
                fileStream.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception : " + ex.Message);
            }
        }
    }
}

方法二：使用WNetAddConnection2和WNetCancelConnection2函数

另外一种访问网络共享文件夹的方法是使用WNetAddConnection2函数和WNetCancelConnection2函数。WNetAddConnection2函数可以将远程共享资源连接到本地驱动器号（例如，将远程共享文件夹映射到本地的一个驱动器号，如 Z:）。WNetCancelConnection2函数用于取消远程共享资源的连接。

具体步骤如下：

1. 在代码中引入System.Runtime.InteropServices命名空间。

using System.Runtime.InteropServices;

1. 声明WNetAddConnection2函数和WNetCancelConnection2方法。

[DllImport("mpr.dll")]
private static extern int WNetAddConnection2A(ref NETRESOURCE lpNetResource, string lpPassword, string lpUsername, int dwFlags);

[DllImport("mpr.dll")]
public static extern int WNetCancelConnection2A(string lpName, int dwFlags, bool fForce);

1. 创建NETRESOURCE对象。

[StructLayout(LayoutKind.Sequential)]
public struct NETRESOURCE
{
    public int dwScope;
    public int dwType;
    public int dwDisplayType;
    public int dwUsage;
    public string lpLocalName;
    public string lpRemoteName;
    public string lpComment;
    public string lpProvider;
}

1. 调用WNetAddConnection2函数来连接共享资源并获取本地驱动器号。

NETRESOURCE nr = new NETRESOURCE();
nr.dwType = RESOURCETYPE_DISK;
nr.lpRemoteName = @"\\servername\sharedfolder";
int result = WNetAddConnection2A(ref nr, "password", "username", 0);

if (result == 0)
{
    Console.WriteLine("Connection established");
    string sharedFolder = @"Z:\folder\file.txt";
    StreamReader reader = new StreamReader(sharedFolder);
    Console.WriteLine(reader.ReadLine());
    reader.Close();
}
else
{
    Console.WriteLine("Connection failed");
}

1. 使用完毕后，使用WNetCancelConnection2函数来取消连接。

int result = WNetCancelConnection2A(@"Z:", 0, true);

if (result == 0)
{
    Console.WriteLine("Connection terminated successfully");
}
else
{
    Console.WriteLine("Connection termination failed");
}

完整代码示例：

using System;
using System.IO;
using System.Runtime.InteropServices;

namespace AccessNetworkSharedFolder
{
    class Program
    {
        [StructLayout(LayoutKind.Sequential)]
        public struct NETRESOURCE
        {
            public int dwScope;
            public int dwType;
            public int dwDisplayType;
            public int dwUsage;
            public string lpLocalName;
            public string lpRemoteName;
            public string lpComment;
            public string lpProvider;
        }

        [DllImport("mpr.dll")]
        private static extern int WNetAddConnection2A(ref NETRESOURCE lpNetResource, string lpPassword, string lpUsername, int dwFlags);

        [DllImport("mpr.dll")]
        public static extern int WNetCancelConnection2A(string lpName, int dwFlags, bool fForce);

        private const int RESOURCETYPE_DISK = 1;

        static void Main(string[] args)
        {
            NETRESOURCE nr = new NETRESOURCE();
            nr.dwType = RESOURCETYPE_DISK;
            nr.lpRemoteName = @"\\servername\sharedfolder";
            int result = WNetAddConnection2A(ref nr, "password", "username", 0);

            if (result == 0)
            {
                Console.WriteLine("Connection established");
                string sharedFolder = @"Z:\folder\file.txt";
                StreamReader reader = new StreamReader(sharedFolder);
                Console.WriteLine(reader.ReadLine());
                reader.Close();
            }
            else
            {
                Console.WriteLine("Connection failed");
            }

            int disconnectResult = WNetCancelConnection2A(@"Z:", 0, true);

            if (disconnectResult == 0)
            {
                Console.WriteLine("Connection terminated successfully");
            }
            else
            {
                Console.WriteLine("Connection termination failed");
            }
        }
    }
}