Scanner scanner = new Scanner(System.in); scanner.close();
hasNext(); 不能得到有空格的字符串!
hasNextLine();以回车键为结束符
next(); nextLine();获取输入的字符串;
hasNextInt(); nextInt();
hasNextFloat(); nextFloat();

Scanner scanner = new Scanner(System.in); scanner.close();
hasNext(); 不能得到有空格的字符串!
hasNextLine();以回车键为结束符
next(); nextLine();获取输入的字符串;
hasNextInt(); nextInt();
hasNextFloat(); nextFloat();