mystringtoken.java

招标投标网上系统

package com.neusoft.util;

/*
 * @(#)StringTokenizer.java	1.26 01/12/03
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */



import java.lang.*;
import java.util.Enumeration;
import java.util.NoSuchElementException;

/**
 * The string tokenizer class allows an application to break a
 * string into tokens. The tokenization method is much simpler than
 * the one used by the <code>StreamTokenizer</code> class. The
 * <code>StringTokenizer</code> methods do not distinguish among
 * identifiers, numbers, and quoted strings, nor do they recognize
 * and skip comments.
 * <p>
 * The set of delimiters (the characters that separate tokens) may
 * be specified either at creation time or on a per-token basis.
 * <p>
 * An instance of <code>StringTokenizer</code> behaves in one of two
 * ways, depending on whether it was created with the
 * <code>returnDelims</code> flag having the value <code>true</code>
 * or <code>false</code>:
 * <ul>
 * <li>If the flag is <code>false</code>, delimiter characters serve to
 *     separate tokens. A token is a maximal sequence of consecutive
 *     characters that are not delimiters.
 * <li>If the flag is <code>true</code>, delimiter characters are themselves
 *     considered to be tokens. A token is thus either one delimiter
 *     character, or a maximal sequence of consecutive characters that are
 *     not delimiters.
 * </ul><p>
 * A <tt>StringTokenizer</tt> object internally maintains a current
 * position within the string to be tokenized. Some operations advance this
 * current position past the characters processed.<p>
 * A token is returned by taking a substring of the string that was used to
 * create the <tt>StringTokenizer</tt> object.
 * <p>
 * The following is one example of the use of the tokenizer. The code:
 * <blockquote><pre>
 *     StringTokenizer st = new StringTokenizer("this is a test");
 *     while (st.hasMoreTokens()) {
 *         println(st.nextToken());
 *     }
 * </pre></blockquote>
 * <p>
 * prints the following output:
 * <blockquote><pre>
 *     this
 *     is
 *     a
 *     test
 * </pre></blockquote>
 *
 * @author  unascribed
 * @version 1.26, 12/03/01
 * @see     java.io.StreamTokenizer
 * @since   JDK1.0
 */
public
class MyStringToken implements Enumeration {
    private int currentPosition;
    private int newPosition;
    private int maxPosition;
    private String str;
    private String delimiters;
    private boolean retDelims;
    private boolean delimsChanged;
    private int delimsIndex;
    private boolean delimsCheck;
    private int delimitersLeng;

    /**
     * maxDelimChar stores the value of the delimiter character with the
     * highest value. It is used to optimize the detection of delimiter
     * characters.
     */
    private char maxDelimChar;

    /**
     * Set maxDelimChar to the highest char in the delimiter set.
     */
    private void setMaxDelimChar() {
        if (delimiters == null) {
            maxDelimChar = 0;
            return;
        }

        char m = 0;
        for (int i = 0; i < delimiters.length(); i++) {
            char c = delimiters.charAt(i);
            if (m < c)
                m = c;
        }
        maxDelimChar = m;
    }

    /**
     * Constructs a string tokenizer for the specified string. All
     * characters in the <code>delim</code> argument are the delimiters
     * for separating tokens.
     * <p>
     * If the <code>returnDelims</code> flag is <code>true</code>, then
     * the delimiter characters are also returned as tokens. Each
     * delimiter is returned as a string of length one. If the flag is
     * <code>false</code>, the delimiter characters are skipped and only
     * serve as separators between tokens.
     *
     * @param   str            a string to be parsed.
     * @param   delim          the delimiters.
     * @param   returnDelims   flag indicating whether to return the delimiters
     *                         as tokens.
     */
    public MyStringToken(String str, String delim, boolean returnDelims) {
        currentPosition = -1;
        newPosition = -1;
        delimsChanged = false;
        this.str = str;
        maxPosition = str.length();
        delimiters = delim;
        retDelims = returnDelims;
        delimsIndex=0;
        delimitersLeng=delimiters.length();
        setMaxDelimChar();
    }

    /**
     * Constructs a string tokenizer for the specified string. The
     * characters in the <code>delim</code> argument are the delimiters
     * for separating tokens. Delimiter characters themselves will not
     * be treated as tokens.
     *
     * @param   str     a string to be parsed.
     * @param   delim   the delimiters.
     */
    public MyStringToken(String str, String delim) {
        this(str, delim, false);
    }

    /**
     * Constructs a string tokenizer for the specified string. The
     * tokenizer uses the default delimiter set, which is
     * <code>"&nbsp;&#92;t&#92;n&#92;r&#92;f"</code>: the space character,
     * the tab character, the newline character, the carriage-return character,
     * and the form-feed character. Delimiter characters themselves will
     * not be treated as tokens.
     *
     * @param   str   a string to be parsed.
     */
    public MyStringToken(String str) {
        this(str, " \t\n\r\f", false);
    }

    /**
     * Skips delimiters starting from the specified position. If retDelims
     * is false, returns the index of the first non-delimiter character at or
     * after startPos. If retDelims is true, startPos is returned.
     */
    private int skipDelimiters(int startPos) {
        if (delimiters == null)
            throw new NullPointerException();

        int position = startPos;
        int curposition=position;
        delimsIndex=0;
        while (!retDelims && (curposition <= maxPosition)) {
            if ((delimsIndex==delimitersLeng)||(curposition==maxPosition)){
                if(delimsIndex==delimitersLeng){
                   position = position + delimsIndex;
                   delimsIndex=0;
               }else{
                   position++;
               }
              break;
            }
            char c = str.charAt(curposition);
            if((c > maxDelimChar) || (delimiters.indexOf(c) < 0)){

                  break;
            }

            if(delimiters.charAt(delimsIndex)==c){
                  delimsIndex++;
            }
            curposition++;
        }
        return position;
    }

    /**
     * Skips ahead from startPos and returns the index of the next delimiter
     * character encountered, or maxPosition if no such delimiter is found.
     */
    private int scanToken(int startPos) {
        int position = startPos;
        delimsIndex=0;
        while (position <=maxPosition) {
            if(delimsIndex==delimitersLeng||position==maxPosition){
              if(delimsIndex==delimitersLeng){
                position = position - delimitersLeng;
                delimsIndex = 0;
              }
              break;
            }
            char c = str.charAt(position);
            if(delimiters.charAt(delimsIndex)==c){
                  delimsIndex++;
            }

            position++;
        }
        return position;
    }

    /**
     * Tests if there are more tokens available from this tokenizer's string.
     * If this method returns <tt>true</tt>, then a subsequent call to
     * <tt>nextToken</tt> with no argument will successfully return a token.
     *
     * @return  <code>true</code> if and only if there is at least one token
     *          in the string after the current position; <code>false</code>
     *          otherwise.
     */
    public boolean hasMoreTokens() {
        /*
         * Temporary store this position and use it in the following
         * nextToken() method only if the delimiters have'nt been changed in
         * that nextToken() invocation.
         */
          if(str.equals("")){
              return false;
          }
          if(newPosition > maxPosition){
              return false;
          }
          if(currentPosition!=-1){
              newPosition = skipDelimiters(currentPosition);
          }else{
              newPosition=0;
          }
        return (newPosition <= maxPosition);
    }

    /**
     * Returns the next token from this string tokenizer.
     *
     * @return     the next token from this string tokenizer.
     * @exception  NoSuchElementException  if there are no more tokens in this
     *               tokenizer's string.
     */
    public String nextToken() {
        /*
         * If next position already computed in hasMoreElements() and
         * delimiters have changed between the computation and this invocation,
         * then use the computed value.
         */
        if(newPosition==maxPosition){
            newPosition++;
            return "";
        }
        currentPosition = (newPosition >= 0 && !delimsChanged) ?
            newPosition : skipDelimiters(currentPosition);
        /* Reset these anyway */
        delimsChanged = false;
        newPosition = -1;

        if (currentPosition >= maxPosition)
            throw new NoSuchElementException();
        int start = currentPosition;
        currentPosition = scanToken(currentPosition);
        if(currentPosition==start){
            return "";
        }else{
          return str.substring(start, currentPosition);
        }
    }

    /**
     * Returns the next token in this string tokenizer's string. First,
     * the set of characters considered to be delimiters by this
     * <tt>StringTokenizer</tt> object is changed to be the characters in
     * the string <tt>delim</tt>. Then the next token in the string
     * after the current position is returned. The current position is
     * advanced beyond the recognized token.  The new delimiter set
     * remains the default after this call.
     *
     * @param      delim   the new delimiters.
     * @return     the next token, after switching to the new delimiter set.
     * @exception  NoSuchElementException  if there are no more tokens in this
     *               tokenizer's string.
     */
    public String nextToken(String delim) {
        delimiters = delim;

        /* delimiter string specified, so set the appropriate flag. */
        delimsChanged = true;

        setMaxDelimChar();
        return nextToken();
    }

    /**
     * Returns the same value as the <code>hasMoreTokens</code>
     * method. It exists so that this class can implement the
     * <code>Enumeration</code> interface.
     *
     * @return  <code>true</code> if there are more tokens;
     *          <code>false</code> otherwise.
     * @see     java.util.Enumeration
     * @see     java.util.StringTokenizer#hasMoreTokens()
     */
    public boolean hasMoreElements() {
        return hasMoreTokens();
    }

    /**
     * Returns the same value as the <code>nextToken</code> method,
     * except that its declared return value is <code>Object</code> rather than
     * <code>String</code>. It exists so that this class can implement the
     * <code>Enumeration</code> interface.
     *
     * @return     the next token in the string.
     * @exception  NoSuchElementException  if there are no more tokens in this
     *               tokenizer's string.
     * @see        java.util.Enumeration
     * @see        java.util.StringTokenizer#nextToken()
     */
    public Object nextElement() {
        return nextToken();
    }

    /**
     * Calculates the number of times that this tokenizer's
     * <code>nextToken</code> method can be called before it generates an
     * exception. The current position is not advanced.
     *
     * @return  the number of tokens remaining in the string using the current
     *          delimiter set.
     * @see     java.util.StringTokenizer#nextToken()
     */
    public int countTokens() {
        int count = 0;
        int currpos = currentPosition;
        while (currpos < maxPosition) {
            currpos = skipDelimiters(currpos);
            if (currpos >= maxPosition)
                break;
            currpos = scanToken(currpos);
            count++;
        }
        return count;
    }
    public static void main(String[] args){
          MyStringToken mst=new MyStringToken("aa=-aa","=-");
          while(mst.hasMoreElements()){
            System.out.println("**"+mst.nextToken()+"**");
            //mst.nextToken();
          }

    }
}