替换字符串中部分字符串，java

public  String replace(String from, String to, String source)      {           if (source == null || from == null || to == null)               return null;           StringBuffer bf = new StringBuffer("");           int index = -1;           while ((index = source.indexOf(from)) != -1)         {               bf.append(source.substring(0, index) + to);               source = source.substring(index + from.length());               index = source.indexOf(from);           }           bf.append(source);           return bf.toString();       }

http://slddyb.blog.51cto.com/2294765/409676