java IO的比较

最近在学习java NIO，然后写了三个程序来测试，分别为传统的IO加上缓冲区，直接缓冲区，和非直接缓冲区三种方式，测试的结果显示为直接缓冲区最快，传统IO加上缓冲区第二，最后是NIO非直接缓冲区。

package com.wmx.test;

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;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

/**
* 通道的主要实现类 java.nio.channels.Channel FileChannel 本地的通道网络的通道 SocketChannel
* ServerSocketChannel DatagramChannel
*
*
* @author Shinelon
*
*/

public class TestChannel {

//共耗时1017毫秒
   //通道之间的数据传输
   public static void main(String[] args) {
       long startTime = System.currentTimeMillis();
       FileChannel inChannel=null;
       FileChannel outChannel=null;
       try {
           inChannel = FileChannel.open(Paths.get("E:/BaiduNetdiskDownload/Microsoft Office 2013(64位).iso"),StandardOpenOption.READ);
           outChannel = FileChannel.open(Paths.get("E:/BaiduNetdiskDownload/1.jpg"),StandardOpenOption.WRITE,StandardOpenOption.READ,StandardOpenOption.CREATE_NEW);
//           inChannel.transferTo(0, inChannel.size(), outChannel);
           outChannel.transferFrom(inChannel, 0, inChannel.size());
       } catch (IOException e) {
           e.printStackTrace();
       }finally{
           if(inChannel!=null){
               try {
                   inChannel.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
           if(outChannel!=null){
               try {
                   outChannel.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
       }
       long endTime = System.currentTimeMillis();
       System.out.println("共耗时"+(endTime-startTime)+"毫秒");
   }

   public static void main3(String[] args) {
       //共耗时2728毫秒
       long startTime = System.currentTimeMillis();
       FileInputStream fis = null;
       FileOutputStream fos = null;
       BufferedInputStream bis = null;
       BufferedOutputStream bos = null;
       try {
           fis = new FileInputStream(new File("E:/BaiduNetdiskDownload/Microsoft Office 2013(64位).iso"));
           fos = new FileOutputStream(new File("E:/BaiduNetdiskDownload/1.jpg"));

           bis = new BufferedInputStream(fis);
           bos = new BufferedOutputStream(fos);

           byte[] by = new byte[1024];
           int len = 0;
           while ((len = bis.read(by)) != -1) {
               bos.write(by);
               bos.flush();
           }
       } catch (FileNotFoundException e) {
           e.printStackTrace();
       } catch (IOException e) {
           e.printStackTrace();
       } finally {
           if (bos != null) {
               try {
                   bos.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
           if (bis != null) {
               try {
                   bis.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
       }
       long endTime = System.currentTimeMillis();
       System.out.println("共耗时" + (endTime - startTime) + "毫秒");
   }

   // 使用直接缓冲区来完成文件的复制
   public static void main(String[] args) {
       // 总耗时1512毫秒提高两倍总耗时1093毫秒
       long startTime = System.currentTimeMillis();
       FileChannel inChannel = null;
       FileChannel outChannel = null;
       MappedByteBuffer inMapperChannel;
       MappedByteBuffer outMapperChannel;
       try {
           inChannel = FileChannel.open(Paths.get("E:/BaiduNetdiskDownload/Microsoft Office 2013(64位).iso"),
                   StandardOpenOption.READ);
           outChannel = FileChannel.open(Paths.get("E:/BaiduNetdiskDownload/4.jpg"), StandardOpenOption.WRITE,
                   StandardOpenOption.READ, StandardOpenOption.CREATE_NEW);

           // 原理和原来allocate
           // 内存映射文件
           inMapperChannel = inChannel.map(MapMode.READ_ONLY, 0, inChannel.size());
           outMapperChannel = outChannel.map(MapMode.READ_WRITE, 0, inChannel.size());

           // 直接对缓冲区进行数据的读写操作
           byte[] by = new byte[inMapperChannel.limit()];
           inMapperChannel.get(by);
           outMapperChannel.put(by);
       } catch (IOException e) {
           e.printStackTrace();
       } finally {
           if (outChannel != null) {
               try {
                   outChannel.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
           if (inChannel != null) {
               try {
                   inChannel.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }

           }

       }
       long endTime = System.currentTimeMillis();
       System.out.println("总耗时" + (endTime - startTime) + "毫秒");
   }

   // 非直接缓冲区
   public static void main1(String[] args) {
       // 总耗时3630毫秒总耗时3592毫秒总耗时3751毫秒
       long startTime = System.currentTimeMillis();
       FileInputStream fis = null;
       FileOutputStream fos = null;
       FileChannel inChannel = null;
       FileChannel outChannel = null;

       try {
           // 1.利用通道来完成文件的复制
           fis = new FileInputStream("E:/BaiduNetdiskDownload/Microsoft Office 2013(64位).iso");
           fos = new FileOutputStream("E:/BaiduNetdiskDownload/5.jpg");
           // 获取通道
           inChannel = fis.getChannel();
           outChannel = fos.getChannel();
           // 分配制定大小的缓冲区
           ByteBuffer buf = ByteBuffer.allocate(1024);

           // 将通道中的数据存入到缓冲区
           while (inChannel.read(buf) != -1) {
               buf.flip();// 切换到读取数据模式
               // 将数据写入到通道
               outChannel.write(buf);
               buf.clear();
           }
       } catch (IOException e) {
           e.printStackTrace();
       } finally {
           if (outChannel != null) {
               try {
                   outChannel.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
           if (inChannel != null) {
               try {
                   inChannel.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
           if (fos != null) {
               try {
                   fos.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
           if (fis != null) {
               try {
                   fis.close();
               } catch (IOException e) {
                   e.printStackTrace();
               }

           }

       }
       long endTime = System.currentTimeMillis();
       System.out.println("总耗时" + (endTime - startTime) + "毫秒");
   }
}

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