Java 复制文件 （文件输入输出流）

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 CopyFileDemo {



    public static void main(String[] args) {

        copyFile("c:\\a.txt","d:\\b.txt");

    }

    

    private static final int OUTPUT_FILE_BUFFER_SIZE = 4*1024;

    

    private static boolean copyFile(String srcdir,String desdir){ 

        //文件流

        FileInputStream fileInputStream = null;

        FileOutputStream fileOutputStream = null;

        

        //使用缓存

        BufferedInputStream bis;

        BufferedOutputStream bos;

        

        //每次读取的长度

        int readLength = 0;

        

        //当前位置

        int position = 0;

        

        //打印信息

        System.out.println("copyFile srcdir: " + srcdir + " desdir:" + desdir);

        //目标文件

        File disFileInfo = null;

        //源文件信息

        File fileInfo = new File(srcdir);

        if(!fileInfo.exists()){

            System.out.println("源文件不存在 返回false");

            return false;

        }

        

        //定义缓存大小

        byte[] buffer  = new byte[OUTPUT_FILE_BUFFER_SIZE];

        try {

            fileInputStream = new FileInputStream(fileInfo);

        } catch (FileNotFoundException e) {

            e.printStackTrace();

            return false;

        }

        //缓冲的输入流

        bis = new BufferedInputStream(fileInputStream, 0x4000);

        

        //检测目标文件是否存在 创建文件

        disFileInfo = new File(desdir);

        if(!disFileInfo.exists()){

            try {

                disFileInfo.createNewFile();

            } catch (IOException e) {

                e.printStackTrace();

                return false;

            }

        }

        

        try {

            fileOutputStream = new FileOutputStream(disFileInfo);

        } catch (FileNotFoundException e) {

            e.printStackTrace();

            return false;

        }

        //缓冲的输出流

        bos = new BufferedOutputStream(fileOutputStream, 0x10000);

        

        while(position != fileInfo.length())

        {

            if(position != fileInfo.length()){

                try {

                    //{@

                    /*核心代码*/

                    //从此字节输入流中给定偏移量处开始将各字节读取到指定的 byte数组中buffer

                    readLength = bis.read(buffer, 0, OUTPUT_FILE_BUFFER_SIZE);

                    //将指定 byte数组buffer中从偏移量 off开始的 len个字节写入此缓冲的输出流

                    bos.write(buffer, 0, readLength);

                    position += readLength;

                    //@}

                } catch (IOException e) {

                    e.printStackTrace();

                    return false;

                }

            }

        }

        

        //依次关闭流

        if(bis != null){

            try {

                bis.close();

            } catch (IOException e) {

                e.printStackTrace();

                return false;

            }

        }

        

        if(bos != null){

            try {

                bos.close();

            } catch (IOException e) {

                e.printStackTrace();

                return false;

            }

        }

        

        if(position == fileInfo.length()){

            System.out.println("copyFile success !!");

            return true;

        }

        

        return false;

    }

}