该代码是Java数据库高级编程宝典中的重要的代码

				package jdbcbook.pub.util;
				
				import java.util.*;
				
				/**
				 * 自己编写的字符串工具
				 */
				public class StringUtil
				{
					// 判断一个字符串是否为空
					public static boolean isEmptyString( String str )
					{
						return str==null || str.length()==0;
					}
				
					// 去掉一个字符串两端的空格
					public static String trim( String str )
					{
						if ( str == null ) return null;
						return str.trim();
					}
				
					public static String[] strTokenizer( String str, String delim )
					{
						if( isEmptyString( trim( str ) ) ) return null;
				
						StringTokenizer st = new StringTokenizer( str, delim );
						String[] result = new String[st.countTokens()];
						int i=0;
						while ( st.hasMoreTokens() ) 
						{
							result[i++] = st.nextToken();
						}
						return result;
					}
				
					public static String getFileName( String filename )
					{
						filename = trim( filename );
				
						if( isEmptyString( filename ) ) return null;
				
						int nIndex = filename.lastIndexOf( "\\" );
						if( nIndex > 0 )
							return filename.substring( nIndex+1 );
						return filename;
					}
				}