java实现简单的IO字节流读写操作

package com.yang.stream;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class FileDemo {
public static void main(String[] args) {
        String oldpath = "d:/a.txt";
        String newpath = "d:/b.txt";
        BufferedInputStream in = null;
        BufferedOutputStream os = null;
try {
in = new BufferedInputStream(new FileInputStream(new File(oldpath)));
            os = new BufferedOutputStream(new FileOutputStream(new File(newpath)));
byte[] b = new byte[1024];
int len = 0;
while((len=in.read(b))!=-1){
                os.write(b, 0, len);
            }
            os.flush();
        } catch (FileNotFoundException e) {
            System.out.println("文件不存在");
        } catch (IOException e) {
            System.out.println("输入输出异常");
        } finally {
if(os!=null){
try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
if(in!=null){
try {
in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        System.out.println("文件传输成功");
    }
}