比较严谨的判断字符串为空

public static boolean isBlank( String input ) {if ( input == null || "".equals( input ) )return true;for ( int i = 0; i < input.length(); i++ ) {char c = input.charAt( i );if ( c != ' ' && c != '\t' && c != '\r' && c != '\n' ){return false;}}return true;}