stringutils.java

Standord Classifier实现了一个基于Java的最大熵分类器。用于模式识别

package edu.stanford.nlp.util;

import java.util.*;
import java.util.regex.*;
import java.io.*;
import java.net.*;

/**
 *  Stringtils is a class for random String things. 
 *
 *  @author Dan Klein
 *  @author Christopher Manning
 *  @version 2003/02/03
 */
public class StringUtils {

    /**
     * Don't let anyone instantiate this class.
     */
    private StringUtils() {}


    /** Say whether this regular expression can be found inside 
     *  this String.  This method provides one of the two "missing"
     *  convenience methods for regular expressions in the String class
     *  in JDK1.4.  This is the one you'll want to use all the time if
     *  you're used to Perl.  What were they smoking?
     *  @param str String to search for match in
     *  @param regex String to compile as the regular expression
     *  @return Whether the regex can be found in str
     */
    public static boolean find(String str, String regex) {
	return Pattern.compile(regex).matcher(str).find();
    }


    /** Say whether this regular expression can be found at the beginning of
     *  this String.  This method provides one of the two "missing"
     *  convenience methods for regular expressions in the String class
     *  in JDK1.4. 
     *  @param str String to search for match at start of
     *  @param regex String to compile as the regular expression
     *  @return Whether the regex can be found at the start of str
     */
    public static boolean lookingAt(String str, String regex) {
	return Pattern.compile(regex).matcher(str).lookingAt();
    }


    /** Say whether this regular expression matches
     *  this String.  This method is the same as the String.matches() method,
     *  and is included just to give a call that is parallel to the other
     *  static regex methods in this class.
     *  @param str String to search for match at start of
     *  @param regex String to compile as the regular expression
     *  @return Whether the regex matches the whole of this str
     */
    public static boolean matches(String str, String regex) {
	return Pattern.compile(regex).matcher(str).matches();
    }


    public static String slurpFile(File file) throws IOException {
        String lineSeparator = System.getProperty("line.separator");
	
	BufferedReader br = new BufferedReader(new FileReader(file));
	String temp;
	StringBuffer buff = new StringBuffer(16000);  // make biggish
	while ((temp = br.readLine()) != null) {
	    buff.append(temp);
	    buff.append(lineSeparator);
	}
	br.close();
	return buff.toString();
    }
  

    public static String slurpURL(URL u) throws IOException {
        String lineSeparator = System.getProperty("line.separator");
	URLConnection uc = u.openConnection();
	InputStream is = uc.getInputStream();
	BufferedReader br = new BufferedReader(new InputStreamReader(is));
	String temp;
	StringBuffer buff = new StringBuffer(16000);  // make biggish
	while ((temp = br.readLine()) != null) {
	    buff.append(temp);
	    buff.append(lineSeparator);
	}
	br.close();
	return buff.toString();
    }
  

  public static String join(List l, String glue) {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < l.size(); i++) {
      if (i > 0)
	sb.append(glue);
      sb.append(l.get(i).toString());
    }
    return sb.toString();
  }
  
  public static String join(Object[] elements,String glue)
  {
      return(join(Arrays.asList(elements),glue));
  }

  public static String join(List l) {
    return join(l, " ");
  }
  
  public static String join(Object[] elements) {
      return(join(elements," "));
  }


  public static List split(String s) {
    return(Arrays.asList(s.split("\\s+")));
  }


  /** Return a String of length a minimum of totalChars characters by
   *  padding the input String str with spaces.  If str is already longer
   *  than totalChars, it is returned unchanged. 
   */
  public static String pad(String str, int totalChars) {
    StringBuffer sb = new StringBuffer(str);
    for (int i = 0; i < totalChars-str.length(); i++) {
      sb.append(" ");
    }
    return sb.toString();
  }

  public static String pad(Object obj, int totalChars) {
    return pad(obj.toString(), totalChars);
  }

  public static String leftPad(String str, int totalChars) {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < totalChars-str.length(); i++) {
      sb.append(" ");
    }
    sb.append(str);
    return sb.toString();
  }

  public static String leftPad(Object obj, int totalChars) {
    return leftPad(obj.toString(), totalChars);
  }
  
  public static String leftPad(int i, int totalChars) {
      return leftPad(new Integer(i), totalChars);
  }

  public static String leftPad(double d, int totalChars) {
      return leftPad(new Double(d), totalChars);
  }
  
  /** Returns s if it's at most maxWidth chars, otherwise chops right side to fit. */
  public static String trim(String s, int maxWidth) {
      if(s.length()<=maxWidth) return(s);
      return(s.substring(0,maxWidth));
  }
  
  public static String trim(Object obj, int maxWidth) {
      return trim(obj.toString(), maxWidth);
  }

  public static String fileNameClean(String s) {
    char[] chars = s.toCharArray();
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < chars.length; i++) {
      char c = chars[i];
      if ((c >= 'A' && c <= 'Z') ||
	  (c >= 'a' && c <= 'z') ||
	  (c >= '0' && c <= '9') ||
	  (c == '_'))
	  sb.append(c);
      else {
	if (c == ' ' ||
	    c == '-')
	  sb.append('_');
	else 
	  sb.append("x"+(int)c+"x");
      }
    }
    return sb.toString();
  }

}