共享内存,写入文件
本文关键字:文件 内存 共享 | 更新日期: 2023-09-27 18:06:34
我在碎片内存中有TXT文件。代码在最后。我一直在尝试将它从内存中取出并写入C:' drive.
中的文件。但是我得到一个错误:
Type 'SharedMemSaveToFile.SharedMemSaver+Data' cannot be marshaled as an
unmanaged structure; no meaningful size or offset can be computed.
如果我改变代码来写内存的CMD,它的工作原理,所以我知道内存在那里。我也试着用这些来写TXT:
System.IO.StreamWriter file = new System.IO.StreamWriter("c:''file.txt");
file.WriteLine(d);
:
using (StreamWriter outfile = new StreamWriter(d + @"C:''file.txt"))
{
outfile.Write(sb.ToString());
}
:
StreamWriter sw = new StreamWriter("file.txt");
sw.Write(d);
sw.Close();
谢谢!
public class Data
{
static void Main(string[] args)
{
SharedMemSaver sf = new SharedMemSaver();
sf.OpenView();
String d = sf.GetData();
System.IO.File.WriteAllText(@"C:'file.txt", d);
}
}
#region Win32 API stuff
public const int FILE_MAP_READ = 0x0004;
[DllImport("Kernel32", CharSet = CharSet.Auto, SetLastError = true)]
internal static extern IntPtr OpenFileMapping(int dwDesiredAccess,
bool bInheritHandle, StringBuilder lpName);
[DllImport("Kernel32", CharSet = CharSet.Auto, SetLastError = true)]
internal static extern IntPtr MapViewOfFile(IntPtr hFileMapping,
int dwDesiredAccess, int dwFileOffsetHigh, int dwFileOffsetLow,
int dwNumberOfBytesToMap);
[DllImport("Kernel32.dll")]
internal static extern bool UnmapViewOfFile(IntPtr map);
[DllImport("kernel32.dll")]
internal static extern bool CloseHandle(IntPtr hObject);
#endregion
private bool fileOpen = false;
private IntPtr map;
private IntPtr handle;
~SharedMemSaver()
{
CloseView();
}
public bool OpenView()
{
if (!fileOpen)
{
StringBuilder sharedMemFile = new StringBuilder("Mem_Values");
handle = OpenFileMapping(FILE_MAP_READ, false, sharedMemFile);
if (handle == IntPtr.Zero)
{
throw new Exception("Unable to open file mapping.");
}
map = MapViewOfFile(handle, FILE_MAP_READ, 0, 0, Marshal.SizeOf((Type)typeof(Data)));
if (map == IntPtr.Zero)
{
throw new Exception("Unable to read shared memory.");
}
fileOpen = true;
}
return fileOpen;
}
public void CloseView()
{
if (fileOpen)
{
UnmapViewOfFile(map);
CloseHandle(handle);
}
}
public String GetData()
{
if (fileOpen)
{
String data = (String)Marshal.PtrToStringAuto(map);
return data;
}
else
{
return null;
}
}
}
}
我强烈建议使用内置的MemoryMappedFile类(在。net 4中新增)
请看Yahia的答案。
但是试图修复你的代码时,错误信息显示all:
你想从Marshal.SizeOf((Type)typeof(Data))
那里得到什么?
它没有大小,因为它没有数据。查看MSDN文档。MapViewOfFile
的最后一个参数"如果该参数为0(零),则映射从指定的偏移量扩展到文件映射的末尾。"