java：I/O 字节流和字符流

int read(byte[] b,int off,int len);

void write(byte[] b,int off,int len);

int read(char[] b,int off,int len);

void write(char[] b,int off,int len);

import java.io.*;
class Test
{
    public static void main(String args[]){
        FileReader fr =null;
        FileWriter fw =null;

        try{
            fr = new FileReader("e://d/from.txt");
            fw = new FileWriter("e://d/to.txt");
            char [] arr =new char[100];
            while(true){
                int temp =fr.read(arr,0,100);
                if(temp == -1){
                break;
                }
                fw.write(arr,0,temp);
            }
        }catch(Exception e){
            System.out.println(e);
        }
        finally{
            try{
                fr.close();
                fw.close();
            }catch(Exception e){
                System.out.println(e);
            }
        }
    }
}