Ch06自定义字符串处理类.ppt

1,第6章 定义字符串处理类,6.1 自定义类的创建 6.2 数据与属性的定义 6.3 构造函数与销毁函数 6.4 Web 中文文本分词相关函数 6.5 密码穷举相关函数 6.6 其它常用函数 6.7 类的使用与测试 6.8 本章小结,2,6.1 自定义类的创建,3,4,Public Enum SortOfCharSet DigitalSet = 0 数字集合 UCaseSet = 1 大写字母集合 LCaseSet = 2 小写字母集合 AllLetters = 3 所有字母集合 AllChars = 4 所有数字和字母集合 UserCharSet = 5 用户字符集 End Enum,6.2 数据与属性的定义,5,Private Const _strDigits As String = “0123456789“ Private Const _strUCase As String = “ABCDEFGHIJKLMNOPQRSTUVWXYZ“ Private Const _strLCase As String = “abcdefghijklmnopqrstuvwxyz“ Private _strCharSet As String Public ReadOnly Property CharSet() As String Get Return _strCharSet End Get End Property Private _eCompare As CompareMethod = CompareMethod.Binary,6,Private Sub SetCharSet(ByVal nCharSet As SortOfCharSet, _ Optional ByVal strUser As String = “) 设置字符集,6.3 构造函数与销毁函数,7,Public Sub New() SetCharSet(SortOfCharSet.AllChars) End Sub Public Sub New(ByVal nCharSet As SortOfCharSet, _ Optional ByVal UserCharSet As String = “) SetCharSet(nCharSet, UserCharSet) End Sub Public Sub Dispose() Me.Finalize() End Sub,8,在中文Web信息处理中，如信息检索、信息抽取，以及图书情报关键词的建立，都需要对文本信息进行分词处理。 对于英文文本，单词用空格分隔，只需要对后缀进行处理，即可进行统计分析。 中文句子是以连续的字符串形式出现的，词与词之间没有间隔，这就涉及到中文文本的分词处理。,6.4 Web 中文文本分词相关函数,9,在中文Web信息处理中，如信息检索、信息抽取，以及图书情报关键词的建立，都需要对文本信息进行分词处理。 对于英文文本，单词用空格分隔，只需要对后缀进行处理，即可进行统计分析。 中文句子是以连续的字符串形式出现的，词与词之间没有间隔，这就涉及到中文文本的分词处理。,6.4 Web 中文文本分词相关函数,10,Public Function NextString(ByVal strSource As String, ByVal strSeg As String) As String 获取 第一个strSeg 以后的字符串 以 “abc/de/ff“, “/“ 为参数，将返回 “de/ff“ Dim I As Integer Dim J As Integer J = strSeg.Length If J = 0 Then Return “ I = strSource.IndexOf(strSeg, _eCompare) If I = -1 Then Return “ Else Return strSource.Substring(I + J) End If End Function,11,Public Function GetLeftString(ByVal strSource As String, ByVal strSeg As String) _ As String 获取 strSeg 左边的字符串 以 “abc/de/ff“, “/“ 为参数，将返回 “abc“ Dim nLoc As Integer nLoc = strSource.IndexOf(strSeg, _eCompare) If nLoc = -1 Then Return strSource Else Return strSource.Substring(0, nLoc) End If End Function,12,Public Function GetNumTail(ByVal strSource As String, ByVal strSeg As String, _ ByVal nLocation As Integer) As String 获取被 strSeg 分隔的第 n 个字符串尾巴，0 将直接返回整个字符串 以 “abc/de/ff“,“/“,1 为参数，将返回 “de/ff“ Dim I As Integer = 0 Dim strTmp As String = strSource If nLocation = 0 Then Return strSource Do While I “ strTmp = NextString(strTmp, strSeg) I = I + 1 Loop Return strTmp End Function,13,Public Function GetNumString(ByVal strSource As String, _ ByVal strSeg As String, _ ByVal nLocation As Integer) As String 获取 第 nLocation 个 strSeg 前面的一段字符串，Start from 0. 以 “abc/de/ff“, “/“, 1 为参数，将返回 “de“ Dim strVal(0) As String Dim strResult() As String strVal(0) = strSeg strResult = strSource.Split(strVal, StringSplitOptions.RemoveEmptyEntries) If nLocation = strResult.Length Then Return “ Else Return strResult(nLocation) End If End Function,14,Public Function GetLastString(ByVal strSource As String, ByVal strSeg As String) _ As String 获取 strSeg 分隔的最后一段子字符串 以 “abc/de/ff“, “/“ 为参数，将返回 “ff“ Dim nLen As Integer Dim nLoc As Integer nLen = strSeg.Length nLoc = strSource.LastIndexOf(strSeg) If nLoc = -1 Then Return “ Else Return strSource.Substring(nLoc + nLen) End If End Function,15,Public Function GetLastString(ByVal strSource As String, ByVal strSeg As String) _ As String 获取 strSeg 分隔的最后一段子字符串 以 “abc/de/ff“, “/“ 为参数，将返回 “ff“ Dim nLen As Integer Dim nLoc As Integer nLen = strSeg.Length nLoc = strSource.LastIndexOf(strSeg) If nLoc = -1 Then Return “ Else Return strSource.Substring(nLoc + nLen) End If End Function,16,Public Function GenNextDate(ByVal strPW As String) As String 输入691231, 输出700101 Dim strTmp As String Dim dt As Date If strPW.Length 6 OrElse CheckLegalChars(strPW, _strDigits) = False Then Return “ strTmp = strPW.Insert(4, “-“) strTmp = strTmp.Insert(2, “-“) Try dt = DateTime.Parse(strTmp) dt = dt.AddDays(1) Return dt.ToString(“yyMMdd“) Catch ex As Exception Return “ End Try End Function,6.5 密码穷举相关函数,17,Public Function GenPreviousDate(ByVal strPW As String) As String 输入700101, 输出691231 Dim strTmp As String Dim dt As DateTime If strPW.Length 6 OrElse CheckLegalChars(strPW, _strDigits) = False _ Then Return “ strTmp = strPW.Insert(4, “-“) strTmp = strTmp.Insert(2, “-“) Try dt = DateTime.Parse(strTmp) dt = dt.AddDays(-1) Return dt.ToString(“yyMMdd“) Catch ex As Exception Return “ End Try End Function,18,Public Function ReplaceSubString(ByVal strSource As String, _ ByVal strOld As String, _ ByVal strNew As String) As String 输入：“ab*cd*e“,“*“,“22“ 输出：“ab22cd*e“,只替换第一个 If strSource.Contains(strOld) = False OrElse strOld = “ OrElse strNew = “ _ Then Return strSource Dim nLocation As Integer = strSource.IndexOf(strOld, _eCompare) Dim nOldLen As Integer = strOld.Length If nLocation = -1 OrElse nOldLen = 0 Then Return strSource Else Return strSource.Substring(0, nLocation) & strNew _ & strSource.Substring(nLocation + nOldLen) End If End Function,6.6 其它常用函数,19,Public oString As StringProcess.StringProcess = New StringProcess.StringProcess,6.7 类的使用与测试,20,StringProcess 自定义类来自多个工程项目的经验总结，可以用于 Web 中文文本分词处理和 Web 知识发现，也可以用于密码穷举和邮政信函的循环编号。 GetNumString 方法常用于从源字符串中获取指定序号的特征数据； On