C# Marshal类基本概念和入门示例程序

刺骨的言语ヽ痛彻心扉 2023-01-19 04:49 18阅读 0赞

marshal:直译为“编排”， 在计算机中特 指将数据按某种描述格式编排出来，通常来说一般是从非文本格式到文本格式的数据转化。  
unmarshal是指marshal的逆过程。比如在WebService中，我们需要把java对象以xml方式表示并在网络间传输，把java对象转化成xml片段的过程就是marshal.

微软对C\#中Marshal类描述的链接在此；

https://docs.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.marshal?view=net-5.0

Provides a collection of methods for allocating unmanaged memory, copying unmanaged memory blocks, and converting managed to unmanaged types, as well as other miscellaneous methods used when interacting with unmanaged code.  
提供一个方法集合，分配非托管内存，拷贝非托管内存块，转换托管和非托管类型，以及一些和非托管代码交互的杂类方法；

这是Marshal类的基本功能；.net一共包含四个Marshal类，每个都有一些方法；

下面来看一个Marshal类基本程序；程序运行结果如下；

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JjYm9ibzIxY24_size_16_color_FFFFFF_t_70][]

代码如下；

using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.Runtime.InteropServices;
    
    namespace marshalDemo1
    {
        public struct Point
        {
            public Int32 x, y;
        }
    
        public partial class Form1 : Form
        {
    
            [DllImport("Kernel32", ExactSpelling = true, SetLastError = true)]
            static extern Boolean CloseHandle(IntPtr h);
    
            public Form1()
            {
                InitializeComponent();
            }
    
            private void button1_Click(object sender, EventArgs e)
            {
                textBox1.Text = Marshal.SystemDefaultCharSize.ToString();
                textBox2.Text = Marshal.SystemMaxDBCSCharSize.ToString();
                textBox3.Text = Marshal.SizeOf(typeof(Point)).ToString();
                Point p = new Point(); 
                textBox4.Text = Marshal.SizeOf(p).ToString();
                IntPtr hglobal = Marshal.AllocHGlobal(100);
                textBox5.Text = hglobal.ToString();
                Marshal.FreeHGlobal(hglobal);
    
                Boolean f = CloseHandle(new IntPtr(-1));
                if (!f)
                {
                    Console.WriteLine("CloseHandle call failed with an error code of: {0}",
                        Marshal.GetLastWin32Error());
                }
            }
        }
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JjYm9ibzIxY24_size_16_color_FFFFFF_t_70]: /images/20221021/231e431cbb6849d695527200425c07ac.png