public static void main(String[] args) { 
 try { 
 //创建字节输出流实例 
 OutputStream out=new FileOutputStream("L:\\test.txt"); 
 //根据字节输出流构建字节缓冲流 
 BufferedOutputStream buf=new BufferedOutputStream(out); 
 String data="好好学习,天天向上"; 
 buf.write(data.getBytes());//写入缓冲区 
 buf.flush();//刷新缓冲区，即把内容写入 
 //关闭流 
 buf.close();//关闭缓冲流时,也会刷新一次缓冲区 
 out.close(); 
} catch (IOException e) { 
 e.printStackTrace(); 
} 
 }

public static void main(String[] args) { 
 try { 
 //创建字节输入流实例 
 InputStream in=new FileInputStream("L:\\test.txt"); 
 //根据字节输入流构建字节缓冲流 
 BufferedInputStream buf=new BufferedInputStream(in); 
 byte[]bytes=new byte[1024]; 
 //数据读取 
 int len=-1; 
 StringBuffer sb=new StringBuffer(); 
 while((len=buf.read(bytes))!=-1) 
 { 
 sb.append(new String(bytes,0,len)); 
 } 
 System.out.println("内容为："+sb); 
 //关闭流 
 buf.close(); 
 in.close(); 

 } catch (IOException e) { 
 e.printStackTrace(); 
 } 
 } 

public static void main(String[] args) { 
 try { 
 Writer w=new FileWriter("L:\\test.txt"); 
 //根据字符输出流创建字符缓冲流 
 BufferedWriter buf=new BufferedWriter(w); 
 //写入数据 
 buf.write("只要功夫深铁杵磨成针"); 
 //刷新流 
 buf.flush(); 
 //关闭流 
 buf.close(); 
 w.close(); 
 } catch (IOException e) { 
 e.printStackTrace(); 
 } 
 } 

public static void main(String[] args) { 
 try { 
 Reader r=new FileReader("L:\\test.txt"); 
 //根据字符输入流创建字符缓冲流 
 BufferedReader buf=new BufferedReader(r); 
 char [] data=new char[512]; 
 //数据读取 
 int len=-1; 
 StringBuilder sb=new StringBuilder(); 
 while((len=buf.read(data))!=-1) 
 { 
 sb.append(new String(data,0,len)); 
 } 
 System.out.println("内容是： "+sb); 
 //关闭流 
 buf.close(); 
 r.close(); 
 } catch (IOException e) { 
 e.printStackTrace(); 
 } 
 }