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;
    }
}