C#——Marshal.StructureToPtr方法简介
来源:互联网 发布:淘宝天机平台论坛 编辑:程序博客网 时间:2024/06/06 10:05
本博客(http://blog.csdn.net/livelylittlefish)贴出作者(三二一、小鱼)相关研究、学习内容所做的笔记,欢
迎广大朋友指正!
具体可以参考http://msdn.microsoft.com。
Marshal.StructureToPtr方法简介
1. 功能及位置
将数据从托管对象封送到非托管内存块,属于.NET Framework 类库
命名空间:System.Runtime.InteropServices
程序集:mscorlib(在 mscorlib.dll 中)
命名空间:System.Runtime.InteropServices
程序集:mscorlib(在 mscorlib.dll 中)
2. 语法
C#:
[ComVisibleAttribute(true)] public static void StructureToPtr (Object structure,IntPtr ptr,bool fDeleteOld);
C++:
C++:
[ComVisibleAttribute(true)]public: static void StructureToPtr (Object^ structure, IntPtr ptr, bool fDeleteOld);
3. 参数说明
structure: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。
ptr: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。
fDeleteOld: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。
ptr: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。
fDeleteOld: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。
4. 异常
异常类型:ArgumentException
条件:structrue参数是泛型类型
条件:structrue参数是泛型类型
5. 备注
StructureToPtr将结构的内容复制到 ptr 参数指向的预分配内存块。如果 fDeleteOld 参数为 true,则使用嵌入指
针上适当的删除 API 来删除最初由 ptr 指向的缓冲区,但该缓冲区必须包含有效数据。此方法为在镜像托管类中指
定的每个引用字段执行清理工作。
假设 ptr 指向非托管内存块。此内存块的布局由相应的托管类 structure 描述。StructureToPtr将字段值从结构封
送到指针。假设 ptr 块包含引用字段,该字段指向当前包含“abc”的字符串缓冲区。假设托管端上相应的字段是包含“vwxyz”的字符串。如果不另行通知它,StructureToPtr将分配一个新的非托管缓冲区来保存“vwxyz”,并将它挂钩到 ptr 块。这将丢弃旧缓冲区“abc”使之漂移而不将其释放回非托管堆。最后,您将得到一个孤立的缓冲区,它表示在代码中存在内存泄漏。如果将 fDeleteOld 参数设置为真,则 StructureToPtr 在继续为“vwxyz”分配新缓冲区之前释放保存“abc”的缓冲区。
6. 举例
定义PERSON结构,并将该结构的一个变量拷贝到非托管内存,再将该内存中的PERSON还原为PERSON对象,观察其内容的变化。
源代码如下:
using System;
using System.Text;
using System.Runtime.InteropServices;
namespace testStructureToPtr
...{
public static class define //define some constant
...{
public const int MAX_LENGTH_OF_IDENTICARDID = 20; //maximum length of identicardid
public const int MAX_LENGTH_OF_NAME = 50; //maximum length of name
public const int MAX_LENGTH_OF_COUNTRY = 50; //maximum length of country
public const int MAX_LENGTH_OF_NATION = 50; //maximum length of nation
public const int MAX_LENGTH_OF_BIRTHDAY = 8; //maximum length of birthday
public const int MAX_LENGTH_OF_ADDRESS = 200; //maximum length of address
}
public struct PERSON //person structure
...{
//MarshalAs:指示如何在托管代码和非托管代码之间封送数据
//UnmanagedType:指定如何将参数或字段封送到非托管内存块
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_IDENTICARDID)]
public byte[] identicardid;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_NAME)]
public byte[] name;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_COUNTRY)]
public byte[] country;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_NATION)]
public byte[] nation;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_BIRTHDAY)]
public byte[] birthday;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_ADDRESS)]
public byte[] address;
}
class testProgram
...{
private static byte _fillChar = 0; //the fill character
//convert string to byte array in Ascii with length is len
public static byte[] CodeBytes(string str, int len)
...{
if (string.IsNullOrEmpty(str))
...{
str = string.Empty;
}
byte[] result = new byte[len];
byte[] strBytes = Encoding.Default.GetBytes(str);
//copy the array converted into result, and fill the remaining bytes with 0
for (int i = 0; i < len; i++)
result[i] = ((i < strBytes.Length) ? strBytes[i] : _fillChar);
return result;
}
//show the person information
public static void ShowPerson(PERSON person)
...{
Console.WriteLine("cardid :" + Encoding.ASCII.GetString(person.identicardid));
Console.WriteLine("name :" + Encoding.ASCII.GetString(person.name));
Console.WriteLine("country :" + Encoding.ASCII.GetString(person.country));
Console.WriteLine("nation :" + Encoding.ASCII.GetString(person.nation));
Console.WriteLine("birthday :" + Encoding.ASCII.GetString(person.birthday));
Console.WriteLine("address :" + Encoding.ASCII.GetString(person.address));
}
static void Main(string[] args)
...{
PERSON person;
person.identicardid = CodeBytes("123456198001011111", define.MAX_LENGTH_OF_IDENTICARDID);
person.name = CodeBytes("jackson", define.MAX_LENGTH_OF_NAME);
person.country = CodeBytes("China", define.MAX_LENGTH_OF_COUNTRY);
person.nation = CodeBytes("HanZu", define.MAX_LENGTH_OF_NATION);
person.birthday = CodeBytes("19800101", define.MAX_LENGTH_OF_BIRTHDAY);
person.address = CodeBytes("Luoshan Road, Shanghai", define.MAX_LENGTH_OF_ADDRESS);
int nSizeOfPerson = Marshal.SizeOf(person);
IntPtr intPtr = Marshal.AllocHGlobal(nSizeOfPerson);
Console.WriteLine("The person infomation is as follows:");
ShowPerson(person);
try
...{
//将数据从托管对象封送到非托管内存块,该内存块开始地址为intPtr
Marshal.StructureToPtr(person, intPtr, true);
//将数据从非托管内存块封送到新分配的指定类型的托管对象anotherPerson
PERSON anotherPerson = (PERSON)Marshal.PtrToStructure(intPtr, typeof(PERSON));
Console.WriteLine("The person after copied is as follows:");
ShowPerson(anotherPerson);
}
catch (ArgumentException)
...{
throw;
}
finally
...{
Marshal.FreeHGlobal(intPtr); //free tha memory
}
}
}
}
using System.Text;
using System.Runtime.InteropServices;
namespace testStructureToPtr
...{
public static class define //define some constant
...{
public const int MAX_LENGTH_OF_IDENTICARDID = 20; //maximum length of identicardid
public const int MAX_LENGTH_OF_NAME = 50; //maximum length of name
public const int MAX_LENGTH_OF_COUNTRY = 50; //maximum length of country
public const int MAX_LENGTH_OF_NATION = 50; //maximum length of nation
public const int MAX_LENGTH_OF_BIRTHDAY = 8; //maximum length of birthday
public const int MAX_LENGTH_OF_ADDRESS = 200; //maximum length of address
}
public struct PERSON //person structure
...{
//MarshalAs:指示如何在托管代码和非托管代码之间封送数据
//UnmanagedType:指定如何将参数或字段封送到非托管内存块
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_IDENTICARDID)]
public byte[] identicardid;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_NAME)]
public byte[] name;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_COUNTRY)]
public byte[] country;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_NATION)]
public byte[] nation;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_BIRTHDAY)]
public byte[] birthday;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = define.MAX_LENGTH_OF_ADDRESS)]
public byte[] address;
}
class testProgram
...{
private static byte _fillChar = 0; //the fill character
//convert string to byte array in Ascii with length is len
public static byte[] CodeBytes(string str, int len)
...{
if (string.IsNullOrEmpty(str))
...{
str = string.Empty;
}
byte[] result = new byte[len];
byte[] strBytes = Encoding.Default.GetBytes(str);
//copy the array converted into result, and fill the remaining bytes with 0
for (int i = 0; i < len; i++)
result[i] = ((i < strBytes.Length) ? strBytes[i] : _fillChar);
return result;
}
//show the person information
public static void ShowPerson(PERSON person)
...{
Console.WriteLine("cardid :" + Encoding.ASCII.GetString(person.identicardid));
Console.WriteLine("name :" + Encoding.ASCII.GetString(person.name));
Console.WriteLine("country :" + Encoding.ASCII.GetString(person.country));
Console.WriteLine("nation :" + Encoding.ASCII.GetString(person.nation));
Console.WriteLine("birthday :" + Encoding.ASCII.GetString(person.birthday));
Console.WriteLine("address :" + Encoding.ASCII.GetString(person.address));
}
static void Main(string[] args)
...{
PERSON person;
person.identicardid = CodeBytes("123456198001011111", define.MAX_LENGTH_OF_IDENTICARDID);
person.name = CodeBytes("jackson", define.MAX_LENGTH_OF_NAME);
person.country = CodeBytes("China", define.MAX_LENGTH_OF_COUNTRY);
person.nation = CodeBytes("HanZu", define.MAX_LENGTH_OF_NATION);
person.birthday = CodeBytes("19800101", define.MAX_LENGTH_OF_BIRTHDAY);
person.address = CodeBytes("Luoshan Road, Shanghai", define.MAX_LENGTH_OF_ADDRESS);
int nSizeOfPerson = Marshal.SizeOf(person);
IntPtr intPtr = Marshal.AllocHGlobal(nSizeOfPerson);
Console.WriteLine("The person infomation is as follows:");
ShowPerson(person);
try
...{
//将数据从托管对象封送到非托管内存块,该内存块开始地址为intPtr
Marshal.StructureToPtr(person, intPtr, true);
//将数据从非托管内存块封送到新分配的指定类型的托管对象anotherPerson
PERSON anotherPerson = (PERSON)Marshal.PtrToStructure(intPtr, typeof(PERSON));
Console.WriteLine("The person after copied is as follows:");
ShowPerson(anotherPerson);
}
catch (ArgumentException)
...{
throw;
}
finally
...{
Marshal.FreeHGlobal(intPtr); //free tha memory
}
}
}
}
运行过程中的对象地址及其内容如下:
intPtr指向的内存块的内容就是程序中对person对象所赋的初值,如下图所示,共计378个字节:
对象person和another的地址及其identicardid成员的地址:
对象person的identicardid成员的内容,即程序中的值123456198001011111,最后的2个字节为0,图中显示的是20个元素的ASCII码的16进制数值:
运行结果如下:
- C#——Marshal.StructureToPtr方法简介
- C#——Marshal.StructureToPtr方法简介
- C# - Marshal.StructureToPtr方法简介
- Marshal类 两个方法StructureToPtr和PtrToStructure实现序列化 字节 数组 转换
- Marshal类的两个方法StructureToPtr和PtrToStructure实现序列化
- Marshal类的两个方法StructureToPtr和PtrToStructure实现序列化
- Marshal类的两个方法StructureToPtr和PtrToStructure实现序列化
- Marshal类的两个方法StructureToPtr和PtrToStructure实现序列化
- Marshal类的两个方法StructureToPtr和PtrToStructure实现序列化
- Marshal类的两个方法StructureToPtr和PtrToStructure实现序列化
- C#关于使用Marshal.StructureToPtr保存文件
- Marshal.StructureToPtr(Object, IntPtr, Boolean)[将数据从托管对象封送到非托管内存块]
- Marshal.GetDelegateForFunctionPointer 方法和Marshal.GetFunctionPointerForDelegate 方法
- Python的marshal模块简介
- 微软Marshal.ReleaseComObject 方法的来龙去脉
- 微软Marshal.ReleaseComObject 方法的来龙去脉
- c#中Marshal.Copy方法的使用
- c#中Marshal.Copy()方法的使用
- 利用DEEP Table做层次XML输出(原文转自网络)
- 第一遍自学C#过程中的一些疑惑
- html读取xml数据实例一
- VB.NET(VS2005) 使用API的尴尬 (垃圾回收器 FUCK API)
- sipX简介
- C#——Marshal.StructureToPtr方法简介
- Android Say Hello 3
- PHP入门笔试题
- JDBC操作DB2 Clob、Blob字段的Bug探究
- 用java打造任意形状窗口和透明窗口
- IMP 数据库版本不对引起的错误
- 正则表达示收藏
- dbcc
- 如何在运行时确定对象类型(RTTI)