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关于java.util.regex 包中新增字符替换方法的比较

 2008-01-05 19:20:27 来源:WEB开发网   
核心提示:代码如下:import java.util.regex.*;public class regex {public regex() {}public static String replaceByRegex (String input,String toChg,String chgTo) {StringBuffer sb

  代码如下:
  import java.util.regex.*;
  
  public class regex {
  
   public regex() {
  
   }
  
   public static String replaceByRegex (String input,String toChg,String chgTo) {
  
    StringBuffer sb = null;
  
    if (input==nullinput.length()==0) return input;
  
    if (toChg==nulltoChg.length()==0) return input;
  
    Pattern chagePattern = Pattern.compile(toChg);
  
    Matcher inputMatcher = chagePattern.matcher(input);
  
    sb = new StringBuffer();
  
    while (inputMatcher.find()) {
  
     inputMatcher.appendReplacement(sb,chgTo);
  
    }
  
    inputMatcher.appendTail(sb);
  
    return sb.toString();
  
   }
  
   public static String replaceByStringBuffer(String _old,String _str,String _new)
  
   {
  
    if (_old==null) {return null;}
  
    StringBuffer _temp=new StringBuffer();
  
    int i=0;
  
    int j=0;
  
     while((j=_old.indexOf(_str,0))!=-1)
  
     {
  
      _temp.append(_old.substring(0,j)+_new);
  
      _old=_old.substring(j+_str.length());
  
     }
  
    _temp.append( _old);
  
    return _temp.toString();
  
    }
  
    public static String replaceByString(String _old,String _str,String _new)
  
    {
  
     if (_old==null) {return null;}
  
     String _temp="";
  
     int i=0;
  
     int j=0;
  
      while((j=_old.indexOf(_str,0))!=-1)
  
      {
  
       _temp+=_old.substring(0,j)+_new;
  
       _old=_old.substring(j+_str.length());
  
      }
  
     _temp+=_old;
  
     return _temp;
  
   }
  
   public static void main(String[] args) throws Throwable {
  
    String tmp = "the the ii bb ttisc hisadf. oeoflaksdjflkjeivnlaskdfjiieiah";
  
    long t = System.currentTimeMillis();
  
    for (int i=0;i<100000;i++,regex.replaceByStringBuffer(tmp,"i","WW"));
  
    System.out.PRintln("replace it by string buffer :"+(System.currentTimeMillis()-t));
  
    t = System.currentTimeMillis();
  
    for (int i=0;i<100000;i++,regex.replaceByString(tmp,"i","WW"));
  
    System.out.println("replace it by string :"+(System.currentTimeMillis()-t));
  
    t = System.currentTimeMillis();
  
    for (int i=0;i<100000;i++,regex.replaceByRegex(tmp,"i","WW"));
  
    System.out.println("replace it by regex :"+(System.currentTimeMillis()-t));
  
   }
  
  }
  
  测试结果:
  replace it by string buffer :2443
  
  replace it by string :3305
  
  replace it by regex :4226
  
  可见,

Tags:关于 java util

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