137 lines
6.2 KiB
VB.net
137 lines
6.2 KiB
VB.net
#Region "Microsoft.VisualBasic::29053b400a3a14f972760567b564efce, Microsoft.VisualBasic.Core\Serialization\BinaryDumping\StructSerializer.vb"
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' Author:
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'
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' asuka (amethyst.asuka@gcmodeller.org)
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' xie (genetics@smrucc.org)
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' xieguigang (xie.guigang@live.com)
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'
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' Copyright (c) 2018 GPL3 Licensed
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'
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'
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' GNU GENERAL PUBLIC LICENSE (GPL3)
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'
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'
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' This program is free software: you can redistribute it and/or modify
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' it under the terms of the GNU General Public License as published by
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' the Free Software Foundation, either version 3 of the License, or
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' (at your option) any later version.
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'
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' This program is distributed in the hope that it will be useful,
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' but WITHOUT ANY WARRANTY; without even the implied warranty of
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' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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' GNU General Public License for more details.
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'
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' You should have received a copy of the GNU General Public License
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' along with this program. If not, see <http://www.gnu.org/licenses/>.
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' /********************************************************************************/
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' Summaries:
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' Module StructSerializer
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'
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' Function: ByteToStructure, StructureToByte
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'
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'
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' /********************************************************************************/
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#End Region
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Imports System.Runtime.CompilerServices
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Imports System.Runtime.InteropServices
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Namespace Serialization.BinaryDumping
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''' <summary>
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''' Some times these method is not works well, not sure why?
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''' </summary>
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''' <remarks>
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''' http://blog.csdn.net/zztoll/article/details/8695992
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'''
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''' Marshal类的两个方法StructureToPtr和PtrToStructure实现序列化
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'''
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''' 我们主要是使用Marshal类里的两个方法：
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'''
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''' 第一个是StructureToPtr，将数据从托管对象封送到非托管内存块。
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''' 第二个是PtrToStructure，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。
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'''
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''' 只要有了这两个相互转换的方法，我们就可以实现序列化了。
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'''
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''' 首先我们先来看下序列化
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'''
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''' 序列化：
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'''
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''' 有一个前提条件，那就是我们必须要知道需要序列化对象的大小。
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'''
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''' 第一步：我们先求出对象的大小，然后在非托管内存中给它分配相应的内存大小。
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''' 第二步：接着我们就把这个对象封送到刚分配出来的内存中，之后我们会得到一个分配出来的内存块首地址指针。
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''' 第三步：最后我们可以通过这个首地址指针，从指针所指的位置处开始，拷贝数据到指定的byte[]数组中，
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''' 拷贝的长度就是我们为这个对象分配出来的内存大小，得到byte[]数据后，下面的事情我就不用多说了，
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''' 你可以保存到数据库或者文件中。
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'''
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''' 反序列化：
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'''
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''' 序列化的时候我们先将一个对象封送到了非托管内存块中，然后再把内存块中的数据读到byte[]数组中，
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'''
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''' 现在我们反序列化
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'''
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''' 第一步：我们先求出对象的大小，然后在非托管内存中给它分配相应的内存大小。
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''' 第二步：然后把这个byte[]数据拷贝到非托管内存块中。
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''' 第三步：最后再从内存块中封送指定大小的数据到对象中。
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'''
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''' 有一个地方需要注意，那就是因为引用类型的对象我们是无法求的它的实际大小的，所以这里的对象我们只能使用非托管对象，比如struct结构体。
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''' 所以，当我们只是用来存储数据，不涉及任何操作的对象，我们可以把它作为一个结构体来处理，这样我们在序列化的时候可以节省空间开销。
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''' 因为你如果你要是用平常的序列化方法去序列化一个类对象，他所需要的空间开销是要大于你去序列化一个具有相同结构的struct对象。
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''' </remarks>
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Public Module StructSerializer
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' 2016.5.20 debugger exception:
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'
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' Unhandled Exception: System.AccessViolationException: Attempted to read Or write protected memory. This Is often an indication that other memory Is corrupt.
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' at System.Runtime.InteropServices.Marshal.StructureToPtr(Object Structure, IntPtr ptr, Boolean fDeleteOld)
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' at Microsoft.VisualBasic.Serialization.BinaryDumping.StructSerializer.StructureToByte[T](T struct)
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' at EasyDocument.Program.Main()
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' These two function will not works, prefer to the extensions in StructFormatter Module
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''' <summary>
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''' 由结构体转换为byte数组(字符串类型以及Class类型都将会被序列化为内存指针，所以这个函数只适合于值类型的)
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''' </summary>
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'''
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<Extension>
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Public Function StructureToByte(Of T As Structure)(struct As T) As Byte()
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Dim size As Integer = Marshal.SizeOf(GetType(T))
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Dim buffer As Byte() = New Byte(size - 1) {}
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Dim bufferIntPtr As IntPtr = Marshal.AllocHGlobal(size)
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Try
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Marshal.StructureToPtr(struct, bufferIntPtr, True)
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Marshal.Copy(bufferIntPtr, buffer, 0, size)
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Finally
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Marshal.FreeHGlobal(bufferIntPtr)
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End Try
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Return buffer
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End Function
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''' <summary>
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''' 由byte数组转换为结构体(字符串类型以及Class类型都将会被序列化为内存指针，所以这个函数只适合于值类型的)
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''' </summary>
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'''
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<Extension>
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Public Function ByteToStructure(Of T As Structure)(dataBuffer As Byte()) As T
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Dim struct As Object = Nothing
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Dim size As Integer = Marshal.SizeOf(GetType(T))
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Dim allocIntPtr As IntPtr = Marshal.AllocHGlobal(size)
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Try
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Marshal.Copy(dataBuffer, 0, allocIntPtr, size)
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struct = Marshal.PtrToStructure(allocIntPtr, GetType(T))
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Finally
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Marshal.FreeHGlobal(allocIntPtr)
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End Try
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Return DirectCast(struct, T)
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End Function
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End Module
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End Namespace
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