关于C# winform 读取网上文件的问题

C#实现访问网络共享文件夹，使用 WNetAddConnection2A 和 WNetCancelConnection2A。

在目标服务器建立共享文件夹，建立访问账号test;

public enum ERROR_ID
{
ERROR_SUCCESS = 0, // Success
ERROR_BUSY = 170,
ERROR_MORE_DATA = 234,
ERROR_NO_BROWSER_SERVERS_FOUND = 6118,
ERROR_INVALID_LEVEL = 124,
ERROR_ACCESS_DENIED = 5,
ERROR_INVALID_PASSWORD = 86,
ERROR_INVALID_PARAMETER = 87,
ERROR_BAD_DEV_TYPE = 66,
ERROR_NOT_ENOUGH_MEMORY = 8,
ERROR_NETWORK_BUSY = 54,
ERROR_BAD_NETPATH = 53,
ERROR_NO_NETWORK = 1222,
ERROR_INVALID_HANDLE_STATE = 1609,
ERROR_EXTENDED_ERROR = 1208,
ERROR_DEVICE_ALREADY_REMEMBERED = 1202,
ERROR_NO_NET_OR_BAD_PATH = 1203
}

public enum RESOURCE_SCOPE
{
RESOURCE_CONNECTED = 1,
RESOURCE_GLOBALNET = 2,
RESOURCE_REMEMBERED = 3,
RESOURCE_RECENT = 4,
RESOURCE_CONTEXT = 5
}

public enum RESOURCE_TYPE
{
RESOURCETYPE_ANY = 0,
RESOURCETYPE_DISK = 1,
RESOURCETYPE_PRINT = 2,
RESOURCETYPE_RESERVED = 8,
}

public enum RESOURCE_USAGE
{
RESOURCEUSAGE_CONNECTABLE = 1,
RESOURCEUSAGE_CONTAINER = 2,
RESOURCEUSAGE_NOLOCALDEVICE = 4,
RESOURCEUSAGE_SIBLING = 8,
RESOURCEUSAGE_ATTACHED = 16,
RESOURCEUSAGE_ALL = (RESOURCEUSAGE_CONNECTABLE | RESOURCEUSAGE_CONTAINER | RESOURCEUSAGE_ATTACHED),
}

public enum RESOURCE_DISPLAYTYPE
{
RESOURCEDISPLAYTYPE_GENERIC = 0,
RESOURCEDISPLAYTYPE_DOMAIN = 1,
RESOURCEDISPLAYTYPE_SERVER = 2,
RESOURCEDISPLAYTYPE_SHARE = 3,
RESOURCEDISPLAYTYPE_FILE = 4,
RESOURCEDISPLAYTYPE_GROUP = 5,
RESOURCEDISPLAYTYPE_NETWORK = 6,
RESOURCEDISPLAYTYPE_ROOT = 7,
RESOURCEDISPLAYTYPE_SHAREADMIN = 8,
RESOURCEDISPLAYTYPE_DIRECTORY = 9,
RESOURCEDISPLAYTYPE_TREE = 10,
RESOURCEDISPLAYTYPE_NDSCONTAINER = 11
}

[StructLayout(LayoutKind.Sequential)]
public struct NETRESOURCE
{
public RESOURCE_SCOPE dwScope;
public RESOURCE_TYPE dwType;
public RESOURCE_DISPLAYTYPE dwDisplayType;
public RESOURCE_USAGE dwUsage;

[MarshalAs(UnmanagedType.LPStr)]
public string lpLocalName;

[MarshalAs(UnmanagedType.LPStr)]
public string lpRemoteName;

[MarshalAs(UnmanagedType.LPStr)]
public string lpComment;

[MarshalAs(UnmanagedType.LPStr)]
public string lpProvider;
}

public class NetworkConnection
{

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

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

public static int Connect (string remotePath, string localPath, string username, string password)
{
NETRESOURCE[] share_driver = new NETRESOURCE[1];
share_driver[0].dwScope = RESOURCE_SCOPE.RESOURCE_GLOBALNET;
share_driver[0].dwType = RESOURCE_TYPE.RESOURCETYPE_DISK;
share_driver[0].dwDisplayType = RESOURCE_DISPLAYTYPE.RESOURCEDISPLAYTYPE_SHARE;
share_driver[0].dwUsage = RESOURCE_USAGE.RESOURCEUSAGE_CONNECTABLE;
share_driver[0].lpLocalName = localPath;
share_driver[0].lpRemoteName = remotePath;

Disconnect(localPath);
int ret = WNetAddConnection2A(share_driver, password, username, 1);

return ret;
}

public static int Disconnect (string localpath)
{
return WNetCancelConnection2A(localpath, 1, 1);
}

调用方式：

public static void TestNetWorkConnection()
{
string localpath = "X:";
//int status = NetworkConnection.Connect(@"\\192.168.0.2\test", localpath, @"test", "test");
int status = NetworkConnection.Connect("\\\\192.168.0.2\\test", localpath, @"test", "test");
if (status == (int)ERROR_ID.ERROR_SUCCESS)
{
FileStream fs = new FileStream(localpath + @"\\123.txt", FileMode.OpenOrCreate);
using (StreamWriter stream = new StreamWriter(fs))
{
stream.WriteLine("你好呀，成功了");
stream.Flush();
stream.Close();
}
fs.Close();
}
else
{
Console.WriteLine(status);
}
NetworkConnection.Disconnect(localpath);
}
下载的时候请是用文件流··
如果服务器设置了关闭ping的方法。
就很难实现了·

参考：

http://support.microsoft.com/kb/173011

http://support.microsoft.com/kb/842789

直接定向到网络文件路径就可以打开读取文件内容；
关于winform程序里下载网络文件，我就不太清楚了
不过在Web里直接定向文件路径会弹出保存对话框，可以选择保存或打开。

给你几个方向：
1 通过Sockets方式，按照http协议或者ftp协议（根据该文件实际的访问协议而定）给这个网络文件地址发送下载文件的请求包，然后再从该地址读取流。需要对http协议或者ftp协议有一定的了解。
2 通过dotnet内置的webbrowser控件进行下载。
3 使用dotnet的webclient控件，这个东西实际上是对sockets做了http封装，挺方便 可以试试。

using System.Net;//这个命名空间下

WebClient web = new WebClient(); //这个类。
下面有很多DOWNLOAD方法供你使用。