打印流PrintStream和PrintWriter

/*打印流PrintStream和PrintWriter
打印流:
该流提供了打印方法,可以将各种数据类型的数据都原样打印.

字节打印流
PrintStream
构造难以为函数可以接收的参数类型:
1,file对象.File
2,字符串路径.String
3,字节输出流. OutputStream

字符打印流
PrintWriter
构造函数可以接收的参数类型:
1,file对象　File
2,字符串路径　String
3,字节输出流　OutputStream
4,字符输出流　Writer
*/
import java.io.*;
class  PrintStreamDemo
{
public static void main(String[] args)
{
System.out.println("Hello World!");
BufferedReader bufr =
new BufferedReader(new InputStreamReader(System.in));//读取键盘,System.in是键盘
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("a.txt"),true));//PrintWriter(OutputStream out, boolean autoFlush),true表示自动刷新

String line = null;
while ((line = bufr.readLine())!=null)
{
if ("over".equals(line))
break;
out.println(line.toUpperCase());
out.flush();
}
out.close();
bufr.close();
}
}