java简单的文件读写，字节流和字符串形式

import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.FileReader;

import java.io.IOException;

public class FileSaveAs {

     

File f;

byte[] bit=new byte[100];

/**

* @param args

* @throws IOException 

*/

public static void main(String[] args) throws IOException {

// TODO Auto-generated method 

FileSaveAs filesa=new FileSaveAs();

filesa.Open("f:\\123.txt");

filesa.SaveAS("f:\\12.txt");

}

public void Open(String filename){

f=new File(filename);

if(f.exists()){

try{

   String temp;

FileReader fr=new FileReader(f);

BufferedReader br=new BufferedReader(fr);

while((temp=br.readLine())!=null){System.out.println(temp);}

fr.close();

br.close();

}catch(IOException e){

}

}

}

public void SaveAS(String filename) throws IOException{

File t=new File(filename);

FileOutputStream fot=new FileOutputStream(t);

   FileInputStream fit=new FileInputStream(f);

   fit.read(bit);//以字节形式读取

   fot.write(bit);//以字节形式写入文件

   fit.close();

   fot.close();

   

/*String temp;  ///字符串形式写入文件

t.createNewFile();

BufferedReader br=new BufferedReader(new FileReader(f));

FileWriter fw=new FileWriter(t);

while((temp=br.readLine())!=null){

fw.write(temp);

}

br.close();

fw.close();*/

}

}