C# 中的 StringTokenizer 类

    <p>在Java中，有一个StringTokenizer类，对于分析单词非常有用。</p>

C# 中，似乎没有系统自带的StringTokenizer类，不过，可以自己写一个。

网上搜索到一个非常专业的代码。如下：

using System;
using System.Collections;
using System.Text;
/// <summary>
/// StringTokenizer. A String Tokenizer that accepts Strings as source and delimiter. Only 1 delimiter is supported (either String or char[]).
/// </summary>
public class StringTokenizer
{
private int curIndex;
private int numTokens;
private ArrayList tokens;
private string source;
private string delimiter;
/// &lt;summary&gt;
/// Constructor for StringTokenizer Class.
/// &lt;/summary&gt;
/// 
/// The Source String. 
/// The Delimiter String. If a 0 length delimiter is given, " " (space) is used by default.
///
public StringTokenizer(string source, string delimiter)
{
    this.tokens = new ArrayList(10);
    this.source = source;
    this.delimiter = delimiter;

    if (delimiter.Length &lt;= 0)
    {
        this.delimiter = " ";
    }
    this.Tokenize();
}

///
/// Constructor for StringTokenizer Class.
/// 
/// The Source String.
/// The Delimiter String as a char[]. Note that this is converted into a single String and expects Unicode encoded chars.
/// 
public StringTokenizer(string source, char[] delimiter)
    : this(source, new string(delimiter))
{
}

///
/// Constructor for StringTokenizer Class. The default delimiter of " " (space) is used.
/// 
/// The Source String.
/// 
public StringTokenizer(string source)
    : this(source, "")
{
}

///
/// Empty Constructor. Will create an empty StringTokenizer with no source, no delimiter, and no tokens.
/// If you want to use this StringTokenizer you will have to call the NewSource(string s) method. You may
/// optionally call the NewDelim(string d) or NewDelim(char[] d) methods if you don't with to use the default
/// delimiter of " " (space).
/// 
public StringTokenizer()
    : this("", "")
{

}

private void Tokenize()
{
    string tempSource = this.source;
    string tok = "";
    this.numTokens = 0;
    this.tokens.Clear();
    this.curIndex = 0;

    if (tempSource.IndexOf(this.delimiter) &lt; 0 &amp;&amp; tempSource.Length &gt; 0) {
        this.numTokens = 1;
        this.curIndex = 0;
        this.tokens.Add(tempSource);
        this.tokens.TrimToSize();
        tempSource = "";
    }
    else if (tempSource.IndexOf(this.delimiter) &lt; 0 &amp;&amp; tempSource.Length &lt;= 0)
    {
        this.numTokens = 0;
        this.curIndex = 0;
        this.tokens.TrimToSize();
    }
    while (tempSource.IndexOf(this.delimiter) &gt;= 0)
    {
        // Delimiter at beginning of source String.
        if (tempSource.IndexOf(this.delimiter) == 0)
        {
            if (tempSource.Length &gt; this.delimiter.Length)
            {
                tempSource = tempSource.Substring(this.delimiter.Length);
            }
            else
            {
                tempSource = "";
            }
        }
        else
        {
            tok = tempSource.Substring(0, tempSource.IndexOf(this.delimiter));
            this.tokens.Add(tok);
            if (tempSource.Length &gt; (this.delimiter.Length + tok.Length))
            {
                tempSource = tempSource.Substring(this.delimiter.Length + tok.Length);
            }
            else
            {
                tempSource = "";
            }
        }
    }
    // we may have a string leftover.
    if (tempSource.Length &gt; 0)
    {
        this.tokens.Add(tempSource);
    }
    this.tokens.TrimToSize();
    this.numTokens = this.tokens.Count;
}

///
/// Method to add or change this Instance's Source string. The delimiter will remain the same (either default of " " (space) or whatever you 
/// constructed this StringTokenizer with or added with NewDelim(string d) or NewDelim(char[] d) ).
/// 
/// The new Source String.
///
public void NewSource(string newSource)
{
    this.source = newSource;
    this.Tokenize();
}

///
/// Method to add or change this Instance's Delimiter string. The source string will remain the same (either empty if you used Empty Constructor, or 
/// the previous value of source from the call to a parameterized constructor or NewSource(string s) ).
/// 
/// The new Delimiter String
/// 
public void NewDelim(string newDel)
{
    if (newDel.Length == 0)
    {
        this.delimiter = " ";
    }
    else
    {
        this.delimiter = newDel;
    }
    this.Tokenize();
}

///
/// Method to add or change this Instance's Delimiter string. The source string will remain the same (either empty if you used Empty Constructor, or 
/// the previous vlaue of source from the call to a parameterized constructor or NewSource(string s) ).
/// 
/// The New Delimiter as a char[]. Note that this is converted into a single String and expects Unicode encoded chars.
/// 
public void NewDelim(char[] newDel)
{
    string temp = new String(newDel);
    if (temp.Length == 0)
    {
        this.delimiter = " ";
    }
    else
    {
        this.delimiter = temp;
    }
    this.Tokenize();
}

///
/// Method to get the number of tokens in this StringTokenizer.
/// 
/// The number fo Tokens in the internal ArrayList.
///
public int CountTokens()
{
    return this.tokens.Count;
}

///
/// Method to probe for more tokens.
/// 
/// true if there are more tokens; false otherwise.
/// 
public bool HasMoreTokens() {
    if (this.curIndex &lt;= (this.tokens.Count -1)) {
        return true;
    } else {
        return false;
    }
}

///
/// Method to get the next (string) token of this StringTokenizer.
/// 
/// A string representing the next token; null if no tokens or more tokens.
/// 
public string NextToken() {
    string returnString = "";
    if (this.curIndex &lt;= this.tokens.Count -1) {
        returnString = (string)tokens[curIndex];
        this.curIndex ++;
        return returnString;
    } else {
        return null;
    }
}

///
/// Gets the Source string of this StringTokenizer.
/// 
/// A string representing the current Source.
/// 
public string Source {
    get {
        return this.source;
    }
}

///
/// Gets the Delimiter string of this StringTokenizer.
/// 
/// A string representing the current Delimiter.
/// 
public string Delimeter {
    get {
        return this.delimiter;
    }
}

///
/// Gets the tokens of this StringTokenizer.

    ///
    /// 涂鸦添加此属性过程，以便调用。
///
public ArrayList Tokens {
get {
return this.tokens;
}
}
}