using System;

using System.Collections.Generic;

using System.Linq;

using System.Runtime.InteropServices;

using System.Text;

using System.Threading.Tasks;

namespace GCHandleExcerse

{

    class Program

    {

        static void Main(string[] args)

        {

            People p1 = new People(10,180,"李白");

            byte[]buff=Struct2Bytes(p1);

            foreach (var i in buff)

            {

                Console.Write(i+"\t");

            }

            People p2= ByteToStruct<People>(buff);

            Console.WriteLine();

            Console.WriteLine(p2.Age+"\t"+p2.Name+"\t"+p2.Height);//输出10 李白 180

            Console.ReadKey();

        }

        //结构体转换为byte数组

        private static byte[] Struct2Bytes(object o)

        {

            // create a new byte buffer the size of your struct

            byte[] buffer = new byte[Marshal.SizeOf(o)];

            // pin the buffer so we can copy data into it w/o GC collecting it

            GCHandle bufferHandle = GCHandle.Alloc(buffer, GCHandleType.Pinned);//为指定的对象分配句柄，不通过GC回收,而是通过手动释放

            // copy the struct data into the buffer

            //StructureToPtr参数1：托管对象，包含要封送的数据。该对象必须是格式化类的实例。

            //StructureToPtr参数2：指向非托管内存块的指针，必须在调用此方法之前分配该指针。

            //StructureToPtr参数3：设置为 true 可在执行Marshal.DestroyStructure方法前对 ptr 参数调用此方法。请注意，传递 false 可导致内存泄漏。

            // bufferHandle.AddrOfPinnedObject():检索对象的地址并返回

            Marshal.StructureToPtr(o, bufferHandle.AddrOfPinnedObject(), false);//将数据从托管对象封送到非托管内存块。

            // free the GC handle

            bufferHandle.Free();

            return buffer;

        }

        //将byte数组转换为结构体

        public static T ByteToStruct<T>(byte[] by) where T : struct

        {

            int objectSize = Marshal.SizeOf(typeof(T));

            if (objectSize > by.Length) return default(T);

            // 分配内存

            IntPtr buffer = Marshal.AllocHGlobal(objectSize);

            // 将数据复制到内存中

            Marshal.Copy(by, 0, buffer, objectSize);

            // Push the memory into a new struct of type (T).将数据封送到结构体T中

            T returnStruct = (T)Marshal.PtrToStructure(buffer, typeof(T));

            // Free the unmanaged memory block.释放内存

            Marshal.FreeHGlobal(buffer);

            return returnStruct;

        }

    }

    struct People

    {

        public uint Age;

        public ushort Height;

        public string Name;

        public People(uint age, ushort height, string name)

        {

            this.Age = age;

            this.Height = height;

            this.Name = name;

        }

    }

}