几种读取文件的方式和耗时（inputStream，BufferedInputStream，FileChannel, directMemory, pipe）

public class IOTestMain {
    public static void main (String s[]){
        IOTestMain ioTestMain = new IOTestMain();
        ioTestMain.readFileTest();
    }

    private void closeOutStream (OutputStream stream){
        if (stream != null){
            try{
                stream.close();
            }catch (IOException e){
                System.out.println(e.getMessage());
            }

        }
    }
    private void closeInStream (InputStream inputStream){
        if (inputStream != null){
            try{
                inputStream.close();
            }catch (IOException e){
                System.out.println(e.getMessage());
            }

        }
    }
    //异步任务
    private void runTask(Pipe pipe,long fileLength,File in) {
        try(ZipOutputStream zos = new ZipOutputStream(Channels.newOutputStream(pipe.sink()));
            WritableByteChannel out = Channels.newChannel(zos)) {
            for (int i = 0; i < 10; i++) {
                //System.out.println("Begin"+i);
                zos.putNextEntry(new ZipEntry("test"+i+".txt"));
                FileChannel jpgChannel = new FileInputStream(in).getChannel();
                jpgChannel.transferTo(0, fileLength, out);
                jpgChannel.close();
            }
            zos.closeEntry();
            //zos.finish();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    public void readFileTest(){
        long time = System.currentTimeMillis();
        File zipFile = new File("C:\projects\dbdatafile\test.rar");
        File in = new File("C:\projects\dbdatafile\test.txt");
        ZipOutputStream zipOutputStream = null;
        FileOutputStream fileOutputStream = null;
        InputStream inputStream = null;
        ///use buffer
        BufferedInputStream bufferedInputStream = null;
        BufferedOutputStream bufferedOutputStream = null;

        //use file channel
        FileChannel fileChannel = null;
        WritableByteChannel writableByteChannel = null;

        MappedByteBuffer mappedByteBuffer = null;
        try{
            fileOutputStream = new FileOutputStream(zipFile);

            //第五种 异步方式耗时1.5+ S
            writableByteChannel = Channels.newChannel(fileOutputStream);
            Pipe pipe = Pipe.open();
            CompletableFuture.runAsync(() ->runTask(pipe,in.length(),in));
            ReadableByteChannel readableByteChannel = pipe.source();
            ByteBuffer buffer = ByteBuffer.allocate(((int) in.length()*10));
            while (readableByteChannel.read(buffer)>= 0) {
                buffer.flip();
                writableByteChannel.write(buffer);
                buffer.clear();
            }
            if (writableByteChannel != null && writableByteChannel.isOpen()){
                writableByteChannel.close();//如果不close，后面又直接重新new，会导致数据写不到磁盘
            }
            for ( int i = 0;i<10;i++){
                if (zipOutputStream == null){
                    zipOutputStream = new ZipOutputStream(fileOutputStream);
                }
                inputStream = new FileInputStream(in);
                bufferedInputStream = new BufferedInputStream(inputStream);
                zipOutputStream.putNextEntry(new ZipEntry("test"+i+".txt"));
                bufferedOutputStream = new BufferedOutputStream(zipOutputStream);
                fileChannel = ((FileInputStream) inputStream).getChannel();
                writableByteChannel = Channels.newChannel(zipOutputStream);
                int temp = 0;
                //第一种方式耗时间20+秒
                while ((temp = inputStream.read())!= -1){
                    zipOutputStream.write(temp);
                }
                //第二种方式耗时间0.8+秒
                while ((temp = bufferedInputStream.read())!= -1){
                    bufferedOutputStream.write(temp);
                }
                //第三种方式耗时间0.4+秒
                fileChannel.transferTo(0,in.length(),writableByteChannel);
                //第四种，使用java堆外内存做缓冲区,耗时0.4+秒
                mappedByteBuffer =
                        new RandomAccessFile(in,"r").getChannel().map(FileChannel.MapMode.READ_ONLY,0,in.length());
                writableByteChannel.write(mappedByteBuffer);
                closeInStream(inputStream);
                inputStream = null;
            }
            closeOutStream(zipOutputStream);
            zipOutputStream = null;
        }catch (Exception e){
            System.out.println("1:"+e.getStackTrace()+e.getMessage());
        }finally {
            closeOutStream(fileOutputStream);
            closeOutStream(zipOutputStream);
            closeOutStream(bufferedOutputStream);
            try{
                if (writableByteChannel != null && writableByteChannel.isOpen()){
                    writableByteChannel.close();
                }
            }catch (Exception e){
                System.out.println("3.2:"+e.getStackTrace());
            }
            closeInStream(inputStream);
            closeInStream(bufferedInputStream);
            try{
                if (fileChannel != null && fileChannel.isOpen()){
                    fileChannel.close();
                }
            }catch (Exception e){
                System.out.println("6:"+e.getStackTrace());
            }

        }
        printTimeCost(time);
    }
    private void printTimeCost(long timestart){
        long timeNow = System.currentTimeMillis();
        System.out.println("cost Time is : " + (timeNow -timestart));
    }

}