三种读取文件的方式（inputStream，BufferedInputStream，FileChannel）

package com.qzl.learn;

import javax.annotation.processing.SupportedSourceVersion;
import java.io.*;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

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

    public void readFileTest(){
        long time = System.currentTimeMillis();
        File zipFile = new File("C:\\projects\\dbdatafile\\test.rar");
        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;
        try{
            fileOutputStream = new FileOutputStream(zipFile);
            zipOutputStream = new ZipOutputStream(fileOutputStream);
            for ( int i = 0;i<10;i++){
                File in = new File("C:\\projects\\dbdatafile\\test.txt");
                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;
//三种方式用一种就可以了
                //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);
                inputStream.close();
                inputStream = null;
            }
            zipOutputStream.closeEntry();
            zipOutputStream.finish();
        }catch (Exception e){
            System.out.println("1:"+e.getStackTrace());
        }finally {
            try{
                if (fileOutputStream != null ){
                    fileOutputStream.close();
                }
            }catch (Exception e){
                System.out.println("2:"+e.getStackTrace());
            }
            try{
                if (zipOutputStream != null){
                    zipOutputStream.close();
                }
            }catch (Exception e){
                System.out.println("3:"+e.getStackTrace());
            }
            try{
                if (bufferedOutputStream != null){
                    bufferedOutputStream.close();
                }
            }catch (Exception e){
                System.out.println("3.1:"+e.getStackTrace());
            }
            try{
                if (writableByteChannel != null && writableByteChannel.isOpen()){
                    writableByteChannel.close();
                }
            }catch (Exception e){
                System.out.println("3.2:"+e.getStackTrace());
            }
            try{
                if (inputStream != null){
                    inputStream.close();
                }
            }catch (Exception e){
                System.out.println("4:"+e.getStackTrace());
            }
            try{
                if (bufferedInputStream != null){
                    bufferedInputStream.close();
                }
            }catch (Exception e){
                System.out.println("5:"+e.getStackTrace());
            }
            try{
                if (fileChannel != null && fileChannel.isOpen()){
                    fileChannel.close();
                }
            }catch (Exception e){
                System.out.println("5:"+e.getStackTrace());
            }
        }
        printTimeCost(time);
    }
    private void printTimeCost(long timestart){
        long timeNow = System.currentTimeMillis();
        System.out.println("cost Time is : " + (timeNow -timestart));
    }
}

标签：zipOutputStream,BufferedInputStream,System,inputStream,FileChannel,println,new,n
来源： https://www.cnblogs.com/thinkqin/p/11957720.html