NIO内存映射

package nio;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

public class MappedByteBufferTest {

 private static String sourceFileName = "UCS_PM_1.1.5_EN.sql";
 private static String dstFileNameByMappedBuffer = "new.sql";
 private static String dstFileNameByFileCopy = "new1.sql";
 private static String dstFileNameByAllocateDirect = "new2.sql";
 private static FileChannel readChannel, writeChannel;
 private static long start;
 private static long length;

 public static void main(String[] args) throws Exception {
  mapBufferWriteFile();    //使用内存映射流来完成文件复制
  testFileCopy();         //使用普通的IO流来完成文件复制
  allocateDirectWriteFile();      //使用DirectMemory来完成文件复制
 }   

 public static void mapBufferWriteFile() {
  try {
   start = System.currentTimeMillis();
   RandomAccessFile fos = new RandomAccessFile(dstFileNameByMappedBuffer, "rw");
   writeChannel = fos.getChannel();
   //writeChannel.position(writeChannel.size());  append to file end position
   
   RandomAccessFile fis = new RandomAccessFile(sourceFileName, "r");
   readChannel = fis.getChannel();
   length = readChannel.size();
   MappedByteBuffer mbb = readChannel.map(FileChannel.MapMode.READ_ONLY, 0, length);
   writeChannel.write(mbb);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   try {
    readChannel.close();
    writeChannel.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
   System.out.println("mapBufferWriteFile:" + (System.currentTimeMillis() - start));
  }
 }
 
 private static void testFileCopy() {
  start = System.currentTimeMillis();
  BufferedInputStream bis =null;
  BufferedOutputStream bos = null;
  try {
   bis = new BufferedInputStream(new FileInputStream(sourceFileName));
   bos = new BufferedOutputStream(new FileOutputStream(dstFileNameByFileCopy));
   byte[] bytes = new byte[1024];
   int index = 0;
   int b = bis.read();
   while(b != -1){
    bytes[index] = (byte) b;
    index ++;
    if(index == 1023){
     bos.write(bytes, 0, index);
     index = 0;
     b = bis.read();
    }else{
     b = bis.read();
    }
   }
   if(index != 1023){
    bos.write(bytes, 0, index);
   }
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  }catch (IOException e) {
   e.printStackTrace();
  }finally {
   try {
    bis.close();
    bos.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  System.out.println("testFileCopy:" + (System.currentTimeMillis() - start));    
 }
 
 private static void allocateDirectWriteFile() {
  try {
   start = System.currentTimeMillis();
   RandomAccessFile fos = new RandomAccessFile(dstFileNameByAllocateDirect, "rw");
   writeChannel = fos.getChannel();
   
   RandomAccessFile fis = new RandomAccessFile(sourceFileName, "r");
   readChannel = fis.getChannel();
   length = readChannel.size();
   ByteBuffer mbb = ByteBuffer.allocate((int)readChannel.size());
   readChannel.read(mbb);
   mbb.flip();
   writeChannel.write(mbb);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   try {
    readChannel.close();
    writeChannel.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
   System.out.println("allocateDirectWriteFile:" + (System.currentTimeMillis() - start));
  }
 }
}