（3-4）从键盘输入数据。importjava.io.*;publicclassBlank_6{publicstaticvoidmain(String[]args){BufferedReaderbr=null;br=newBufferedReader(newInputStreamReader(System.in));Stringstr=null;System.out.println("请输入内容：");try{str=_________________//读取从键盘输入的数据br.close();}catch(IOExceptione){e.printStackTrace();}System.out.println("输入的内容是："+str);}}