c# - 将字符串数据写入 MemoryMappedFile

Question

我正在学习本教程 here

我很难弄清楚如何将字符串“THIS IS A TEST MESSAGE”存储在内存映射文件中，然后将其从另一端拉出。本教程说使用字节数组。请原谅我，我是新手，先自己尝试。

谢谢，凯文

##Write to mapped file

using System;
using System.IO.MemoryMappedFiles;

class Program1
{
    static void Main()
    {
        // create a memory-mapped file of length 1000 bytes and give it a 'map name' of 'test'
        MemoryMappedFile mmf = MemoryMappedFile.CreateNew("test", 1000);
        // write an integer value of 42 to this file at position 500
        MemoryMappedViewAccessor accessor = mmf.CreateViewAccessor();
        accessor.Write(500, 42);
        Console.WriteLine("Memory-mapped file created!");
        Console.ReadLine(); // pause till enter key is pressed
        // dispose of the memory-mapped file object and its accessor
        accessor.Dispose();
        mmf.Dispose();
    }
}   


##read from mapped file  
using System;
using System.IO.MemoryMappedFiles;
class Program2
{
    static void Main()
    {
        // open the memory-mapped with a 'map name' of 'test'
        MemoryMappedFile mmf = MemoryMappedFile.OpenExisting("test");
        // read the integer value at position 500
        MemoryMappedViewAccessor accessor = mmf.CreateViewAccessor();
        int value = accessor.ReadInt32(500);
        // print it to the console
        Console.WriteLine("The answer is {0}", value);
        // dispose of the memory-mapped file object and its accessor
        accessor.Dispose();
        mmf.Dispose();
    }
}

Answer 1

可以考虑先写字符串的长度，再写字符串的byte[]形式。
例如，如果我想写“Hello”，那么我将它转换成字节:

byte[] Buffer = ASCIIEncoding.ASCII.GetBytes("Hello");

然后在写入内存映射文件的同时执行以下操作。

MemoryMappedFile mmf = MemoryMappedFile.CreateNew("test", 1000);
MemoryMappedViewAccessor accessor = mmf.CreateViewAccessor();
accessor.Write(54, (ushort)Buffer.Length);
accessor.WriteArray(54 + 2, Buffer, 0, Buffer.Length);

首先读取位置 54 并读取 2 个字节来保存字符串的长度。然后您可以读取该长度的数组并将其转换为字符串。

MemoryMappedFile mmf = MemoryMappedFile.CreateNew("test", 1000);
MemoryMappedViewAccessor accessor = mmf.CreateViewAccessor();
ushort Size = accessor.ReadUInt16(54);
byte[] Buffer = new byte[Size];
accessor.ReadArray(54 + 2, Buffer, 0, Buffer.Length); 
MessageBox.Show(ASCIIEncoding.ASCII.GetString(Buffer));