Java读写文件

package com.enorth.mpup.util; 

import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 

public  class Log { 

   public  void logFile(){ 
     
    String filePath= "d://zzz/"; 
     
    String fileName="log.txt"; 
     
    File file = new File(filePath,fileName); 
     
    try { 
        
      InputStream is = new FileInputStream(file); 
        
      OutputStream os=new FileOutputStream("d://zzz/a.txt"); 
        
      byte[] buffer=new byte[400]; 
        
      int length=0; 
        
      while(    (length=is.read(buffer))    >    0     ){ 
        os.write(buffer, 0, length); 
      } 
        
      is.close(); 
        
//      os.write("华师大金卡回答厉害的".getBytes());    //直接写 
        
      os.close(); 
        
    } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
  } 
    
  public static void main(String[] args) { 
    Log log=new Log(); 
    log.logFile(); 
  } 
}