C#的GUID是怎么样生成的

// ==++==

// The use and distribution terms for this software are contained in the file

// named license.txt, which can be found in the root of this distribution.

// By using this software in any fashion, you are agreeing to be bound by the

// terms of this license.

// You must not remove this notice, or any other, from this software.

// ==--==

namespace System {

using System;

using System.Text;

using System.Runtime.InteropServices;

using System.Runtime.CompilerServices;

using System.Globalization;

// Represents a Globally Unique Identifier.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid"]/*' />

[StructLayout(LayoutKind.Sequential)]

[Serializable]

public struct Guid : IFormattable, IComparable

{

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.Empty"]/*' />

public static readonly Guid Empty = new Guid();

////////////////////////////////////////////////////////////////////////////////

// Member variables

////////////////////////////////////////////////////////////////////////////////

private int _a;

private short _b;

private short _c;

private byte _d;

private byte _e;

private byte _f;

private byte _g;

private byte _h;

private byte _i;

private byte _j;

private byte _k;

////////////////////////////////////////////////////////////////////////////////

// Constructors

////////////////////////////////////////////////////////////////////////////////

// Creates a new guid from an array of bytes.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.Guid"]/*' />

public Guid(byte[] b)

{

if (b==null)

throw new ArgumentNullException("b");

if (b.Length != 16)

throw new ArgumentException(String.Format(Environment.GetResourceString("Arg_GuidArrayCtor"), "16"));

_a = ((int)b[0] << 24) | ((int)b[1] << 16) | ((int)b[2] << 8) | b[3];

_b = (short)(((int)b[4] << 8) | b[5]);

_c = (short)(((int)b[6] << 8) | b[7]);

_d = b[8];

_e = b[9];

_f = b[10];

_g = b[11];

_h = b[12];

_i = b[13];

_j = b[14];

_k = b[15];

}

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.Guid1"]/*' />

[CLSCompliant(false)]

public Guid (uint a, ushort b, ushort c, byte d, byte e, byte f, byte g, byte h, byte i, byte j, byte k)

{

_a = (int)a;

_b = (short)b;

_c = (short)c;

_d = d;

_e = e;

_f = f;

_g = g;

_h = h;

_i = i;

_j = j;

_k = k;

}

// Creates a new guid with all contents having value of 0

private Guid(bool blank)

{

// Must initialize value class members even if the native

// function reinitializes them. Compiler appeasement.

_a = 0;

_b = 0;

_c = 0;

_d = 0;

_e = 0;

_f = 0;

_g = 0;

_h = 0;

_i = 0;

_j = 0;

_k = 0;

if (!blank)

CompleteGuid();

}

// Creates a new guid based on the value in the string. The value is made up

// of hex digits speared by the dash ("-"). The string may begin and end with

// brackets ("{", "}").

// The string must be of the form dddddddd-dddd-dddd-dddd-dddddddddddd. where

// d is a hex digit. (That is 8 hex digits, followed by 4, then 4, then 4,

// then 12) such as: "CA761232-ED42-11CE-BACD-00AA0057B223"

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.Guid2"]/*' />

public Guid(String g)

{

if (g==null)

throw new ArgumentNullException("g", "ArgumentNull_String");

int startPos=0;

int temp;

long templ;

int[] spArray = new int[1];

try

{

// Check if it's of the form dddddddd-dddd-dddd-dddd-dddddddddddd

if(g.IndexOf('-', 0) >= 0)

{

String guidString = g.Trim(); //Remove Whitespace

// check to see that it's the proper length

if (guidString[0]=='{') {

if (guidString.Length!=38 || guidString[37]!='}') {

throw new FormatException(Environment.GetResourceString("Format_GuidInvLen"));

}

startPos=1;

}

else if (guidString[0]=='(')

{

if (guidString.Length!=38 || guidString[37]!=')')

{

throw new FormatException(Environment.GetResourceString("Format_GuidInvLen"));

}

startPos=1;

}

else if(guidString.Length != 36) {

throw new FormatException(Environment.GetResourceString("Format_GuidInvLen"));

}

if (guidString[8+startPos] != '-' ||

guidString[13+startPos] != '-' ||

guidString[18+startPos] != '-' ||

guidString[23+startPos] != '-') {

throw new FormatException(Environment.GetResourceString("Format_GuidDashes"));

}

spArray[0]=startPos;

_a = TryParse(guidString, spArray,8);

spArray[0]++; //Increment past the '-';

_b = (short)TryParse(guidString, spArray,4);

spArray[0]++; //Increment past the '-';

_c = (short)TryParse(guidString, spArray,4);

spArray[0]++; //Increment past the '-';

temp=TryParse(guidString, spArray,4);

spArray[0]++; //Increment past the '-';

startPos=spArray[0];

templ = ParseNumbers.StringToLong(guidString, 16, 0, spArray);

if (spArray[0]-startPos!=12) {

throw new FormatException(String.Format(Environment.GetResourceString("Format_GuidInvLen")));

}

_d = (byte)(temp>>8);

_e = (byte)(temp);

temp = (int)(templ >> 32);

_f = (byte)(temp>>8);

_g = (byte)(temp);

temp = (int)(templ);

_h = (byte)(temp>>24);

_i = (byte)(temp>>16);

_j = (byte)(temp>>8);

_k = (byte)(temp);

}

// Else check if it is of the form

// {0xdddddddd,0xdddd,0xdddd,{0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd}}

else if(g.IndexOf('{', 0) >= 0)

{

int numStart = 0;

int numLen = 0;

// Convert to lower case

//g = g.ToLower();

// Eat all of the whitespace

g = EatAllWhitespace(g);

// Check for leading '{'

if(g[0] != '{')

throw new FormatException(Environment.GetResourceString("Format_GuidBrace"));

// Check for '0x'

if(!IsHexPrefix(g, 1))

throw new FormatException(String.Format(Environment.GetResourceString("Format_GuidHexPrefix"), "{0xdddddddd, etc}"));

// Find the end of this hex number (since it is not fixed length)

numStart = 3;

numLen = g.IndexOf(',', numStart) - numStart;

if(numLen <= 0)

throw new FormatException(Environment.GetResourceString("Format_GuidComma"));

// Read in the number

_a = (int) ParseNumbers.StringToInt(g.Substring(numStart, numLen), // first DWORD

16, // hex

ParseNumbers.IsTight); // tight parsing

// Check for '0x'

if(!IsHexPrefix(g, numStart+numLen+1))

throw new FormatException(String.Format(Environment.GetResourceString("Format_GuidHexPrefix"), "{0xdddddddd, 0xdddd, etc}"));

// +3 to get by ',0x'

numStart = numStart + numLen + 3;

numLen = g.IndexOf(',', numStart) - numStart;

if(numLen <= 0)

throw new FormatException(Environment.GetResourceString("Format_GuidComma"));

// Read in the number

_b = (short) ParseNumbers.StringToInt(

g.Substring(numStart, numLen), // first DWORD

16, // hex

ParseNumbers.IsTight); // tight parsing

// Check for '0x'

if(!IsHexPrefix(g, numStart+numLen+1))

throw new FormatException(String.Format(Environment.GetResourceString("Format_GuidHexPrefix"), "{0xdddddddd, 0xdddd, 0xdddd, etc}"));

// +3 to get by ',0x'

numStart = numStart + numLen + 3;

numLen = g.IndexOf(',', numStart) - numStart;

if(numLen <= 0)

throw new FormatException(Environment.GetResourceString("Format_GuidComma"));

// Read in the number

_c = (short) ParseNumbers.StringToInt(

g.Substring(numStart, numLen), // first DWORD

16, // hex

ParseNumbers.IsTight); // tight parsing

// Check for '{'

if(g.Length <= numStart+numLen+1 || g[numStart+numLen+1] != '{')

throw new FormatException(Environment.GetResourceString("Format_GuidBrace"));

// Prepare for loop

numLen++;

byte[] bytes = new byte[8];

for(int i = 0; i < 8; i++)

{

// Check for '0x'

if(!IsHexPrefix(g, numStart+numLen+1))

throw new FormatException(String.Format(Environment.GetResourceString("Format_GuidHexPrefix"), "{

{

0xdd,

}}"));

// +3 to get by ',0x' or '{0x' for first case

numStart = numStart + numLen + 3;

// Calculate number length

if(i < 7) // first 7 cases

{

numLen = g.IndexOf(',', numStart) - numStart;

}

else // last case ends with '}', not ','

{

numLen = g.IndexOf('}', numStart) - numStart;

}

if(numLen <= 0)

throw new FormatException(Environment.GetResourceString("Format_GuidComma"));

// Read in the number

bytes[i] = (byte) Convert.ToInt32(g.Substring(numStart, numLen),16);

}

_d = bytes[0];

_e = bytes[1];

_f = bytes[2];

_g = bytes[3];

_h = bytes[4];

_i = bytes[5];

_j = bytes[6];

_k = bytes[7];

// Check for last '}'

if(numStart+numLen+1 >= g.Length || g[numStart+numLen+1] != '}')

throw new FormatException(Environment.GetResourceString("Format_GuidEndBrace"));

return;

}

else

// Check if it's of the form dddddddddddddddddddddddddddddddd

{

String guidString = g.Trim(); //Remove Whitespace

if(guidString.Length != 32) {

throw new FormatException(Environment.GetResourceString("Format_GuidInvLen"));

}

_a = (int) ParseNumbers.StringToInt(g.Substring(startPos, 8), // first DWORD

16, // hex

ParseNumbers.IsTight); // tight parsing

startPos += 8;

_b = (short) ParseNumbers.StringToInt(g.Substring(startPos, 4),

16,

ParseNumbers.IsTight);

startPos += 4;

_c = (short) ParseNumbers.StringToInt(g.Substring(startPos, 4),

16,

ParseNumbers.IsTight);

startPos += 4;

temp=(short) ParseNumbers.StringToInt(g.Substring(startPos, 4),

16,

ParseNumbers.IsTight);

startPos += 4;

spArray[0] = startPos;

templ = ParseNumbers.StringToLong(guidString, 16, startPos, spArray);

if (spArray[0]-startPos!=12) {

throw new FormatException(String.Format(Environment.GetResourceString("Format_GuidInvLen")));

}

_d = (byte)(temp>>8);

_e = (byte)(temp);

temp = (int)(templ >> 32);

_f = (byte)(temp>>8);

_g = (byte)(temp);

temp = (int)(templ);

_h = (byte)(temp>>24);

_i = (byte)(temp>>16);

_j = (byte)(temp>>8);

_k = (byte)(temp);

}

catch(IndexOutOfRangeException)

{

throw new FormatException(Environment.GetResourceString("Format_GuidUnrecognized"));

}

// Creates a new GUID initialized to the value represented by the arguments.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.Guid3"]/*' />

public Guid(int a, short b, short c, byte[] d)

{

if (d==null)

throw new ArgumentNullException("d");

// Check that array is not too big

if(d.Length != 8)

throw new ArgumentException(String.Format(Environment.GetResourceString("Arg_GuidArrayCtor"), "8"));

_a = a;

_b = b;

_c = c;

_d = d[0];

_e = d[1];

_f = d[2];

_g = d[3];

_h = d[4];

_i = d[5];

_j = d[6];

_k = d[7];

}

// Creates a new GUID initialized to the value represented by the

// arguments. The bytes are specified like this to avoid endianness issues.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.Guid4"]/*' />

public Guid(int a, short b, short c, byte d, byte e, byte f, byte g, byte h, byte i, byte j, byte k)

{

_a = a;

_b = b;

_c = c;

_d = d;

_e = e;

_f = f;

_g = g;

_h = h;

_i = i;

_j = j;

_k = k;

}

private static int TryParse(String str, int []parsePos, int requiredLength) {

int currStart = parsePos[0];

int retVal;

try

{

retVal = ParseNumbers.StringToInt(str, 16, 0, parsePos);

}

catch (FormatException)

{

throw new FormatException(Environment.GetResourceString("Format_GuidUnrecognized"));

}

//If we didn't parse enough characters, there's clearly an error.

if (parsePos[0]-currStart!=requiredLength) {

throw new FormatException(Environment.GetResourceString("Format_GuidUnrecognized"));

}

return retVal;

}

private static String EatAllWhitespace(String str)

{

int newLength = 0;

char[] chArr = new char[str.Length];

char curChar;

// Now get each char from str and if it is not whitespace add it to chArr

for(int i = 0; i < str.Length; i++)

{

curChar = str[i];

if(!Char.IsWhiteSpace(curChar))

{

chArr[newLength++] = curChar;

}

// Return a new string based on chArr

return new String(chArr, 0, newLength);

}

private static bool IsHexPrefix(String str, int i)

{

if(str[i] == '0' && (Char.ToLower(str[i+1], CultureInfo.InvariantCulture) == 'x'))

return true;

else

return false;

}

// Returns an unsigned byte array containing the GUID.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.ToByteArray"]/*' />

public byte[] ToByteArray()

{

byte[] g = new byte[16];

g[0] = (byte)(_a >> 24);

g[1] = (byte)(_a >> 16);

g[2] = (byte)(_a >> 8);

g[3] = (byte)(_a);

g[4] = (byte)(_b >> 8);

g[5] = (byte)(_b);

g[6] = (byte)(_c >> 8);

g[7] = (byte)(_c);

g[8] = _d;

g[9] = _e;

g[10] = _f;

g[11] = _g;

g[12] = _h;

g[13] = _i;

g[14] = _j;

g[15] = _k;

return g;

}

// Returns the guid in "registry" format.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.ToString"]/*' />

public override String ToString()

{

return ToString("D",null);

}

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.GetHashCode"]/*' />

public override int GetHashCode()

{

return _a ^ (((int)_b << 16) | (int)(ushort)_c) ^ (((int)_f << 24) | _k);

}

// Returns true if and only if the guid represented

// by o is the same as this instance.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.Equals"]/*' />

public override bool Equals(Object o)

{

Guid g;

// Check that o is a Guid first

if(o == null || !(o is Guid))

return false;

else g = (Guid) o;

// Now compare each of the elements

if(g._a != _a)

return false;

if(g._b != _b)

return false;

if(g._c != _c)

return false;

if (g._d != _d)

return false;

if (g._e != _e)

return false;

if (g._f != _f)

return false;

if (g._g != _g)

return false;

if (g._h != _h)

return false;

if (g._i != _i)

return false;

if (g._j != _j)

return false;

if (g._k != _k)

return false;

return true;

}

private int GetResult(uint me, uint them) {

if (me<them) {

return -1;

}

return 1;

}

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.CompareTo"]/*' />

public int CompareTo(Object value) {

if (value == null) {

return 1;

}

if (!(value is Guid)) {

throw new ArgumentException(Environment.GetResourceString("Arg_MustBeGuid"));

}

Guid g = (Guid)value;

if (g._a!=this._a) {

return GetResult((uint)this._a, (uint)g._a);

}

if (g._b!=this._b) {

return GetResult((uint)this._b, (uint)g._b);

}

if (g._c!=this._c) {

return GetResult((uint)this._c, (uint)g._c);

}

if (g._d!=this._d) {

return GetResult((uint)this._d, (uint)g._d);

}

if (g._e!=this._e) {

return GetResult((uint)this._e, (uint)g._e);

}

if (g._f!=this._f) {

return GetResult((uint)this._f, (uint)g._f);

}

if (g._g!=this._g) {

return GetResult((uint)this._g, (uint)g._g);

}

if (g._h!=this._h) {

return GetResult((uint)this._h, (uint)g._h);

}

if (g._i!=this._i) {

return GetResult((uint)this._i, (uint)g._i);

}

if (g._j!=this._j) {

return GetResult((uint)this._j, (uint)g._j);

}

if (g._k!=this._k) {

return GetResult((uint)this._k, (uint)g._k);

}

return 0;

}

// Compares two Guids by calling Guid.Equals(Guid).

/* private static bool operator equals(Guid a, Guid b)

{

return a.Equals(b);

}*/

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.operatorEQ"]/*' />

public static bool operator ==(Guid a, Guid b)

{

return a.Equals(b);

}

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.operatorNE"]/*' />

public static bool operator !=(Guid a, Guid b)

{

return !a.Equals(b);

}

// This will fill in the members of Guid using CoCreateGuid.

[MethodImplAttribute(MethodImplOptions.InternalCall)]

private extern void CompleteGuid();

// This will create a new guid. Since we've now decided that constructors should 0-init,

// we need a method that allows users to create a guid.

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.NewGuid"]/*' />

public static Guid NewGuid() {

return new Guid(false);

}

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.ToString1"]/*' />

public String ToString(String format) {

return ToString(format, null);

}

private static char HexToChar(int a)

{

a = a & 0xf;

return (char) ((a > 9) ? a - 10 + 0x61 : a + 0x30);

}

private static int HexsToChars(char[] guidChars, int offset, int a, int b)

{

guidChars[offset++] = HexToChar(a>>4);

guidChars[offset++] = HexToChar(a);

guidChars[offset++] = HexToChar(b>>4);

guidChars[offset++] = HexToChar(b);

return offset;

}

// IFormattable interface

// We currently ignore provider

/// <include file='doc\Guid.uex' path='docs/doc[@for="Guid.ToString2"]/*' />

public String ToString(String format, IFormatProvider provider)

{

if (format == null || format.Length == 0)

format = "D";

char[] guidChars;

int offset = 0;

int strLength = 38;

bool dash = true;

if (String.Compare(format,"N",true, CultureInfo.InvariantCulture) == 0)

{

guidChars = new char[32];

strLength = 32;

dash = false;

}

else if (String.Compare(format,"B",true, CultureInfo.InvariantCulture) == 0)

{

guidChars = new char[38];

guidChars[offset++] = '{';

guidChars[37] = '}';

}

else if (String.Compare(format,"P",true, CultureInfo.InvariantCulture) == 0)

{

guidChars = new char[38];

guidChars[offset++] = '(';

guidChars[37] = ')';

}

else if (String.Compare(format,"D",true, CultureInfo.InvariantCulture) == 0)

{

guidChars = new char[36];

strLength = 36;

}

else

throw new FormatException(Environment.GetResourceString("Format_InvalidGuidFormatSpecification"));

offset = HexsToChars(guidChars, offset, _a >> 24, _a >> 16);

offset = HexsToChars(guidChars, offset, _a >> 8, _a);

if (dash) guidChars[offset++] = '-';

offset = HexsToChars(guidChars, offset, _b >> 8, _b);

if (dash) guidChars[offset++] = '-';

offset = HexsToChars(guidChars, offset, _c >> 8, _c);

if (dash) guidChars[offset++] = '-';

offset = HexsToChars(guidChars, offset, _d, _e);

if (dash) guidChars[offset++] = '-';

offset = HexsToChars(guidChars, offset, _f, _g);

offset = HexsToChars(guidChars, offset, _h, _i);

offset = HexsToChars(guidChars, offset, _j, _k);

return new String(guidChars, 0, strLength);

}

posted on 2005-08-04 01:28 wanna 阅读(4304) 评论(2) 编辑收藏举报