Java开发网 - 下面那个nio教材的试验

Topic: 下面那个nio教材的试验

1.下面那个nio教材的试验

Posted by: alin_ass
Posted on: 2003-11-25 23:14

package io;
import java.io.*;
import java.nio.*;
import java.nio.channels.*;

public class CopyFile {
  FileChannel fcin;
  FileChannel fcout;
  int bufferSize;

  CopyFile(String infile, String outfile, int bufferSize) throws Exception {
    fcin = new FileInputStream(infile).getChannel();
    fcout = new FileOutputStream(outfile).getChannel();
    this.bufferSize = bufferSize;
  }

  public void copy() throws Exception {
    ByteBuffer buffer = ByteBuffer.allocate(bufferSize);
    for (int i = 0; i < 100000; i++) {
      while (true) {
        buffer.clear();
        //正常情况下，应该是按缓冲区的大小分批把通道中的字节读入缓冲区
        int r = fcin.read(buffer);
        if (r == -1) {
          break;
        }
        buffer.flip();
        fcout.write(buffer);
      }
    }
  }

  static public void main(String args[]) {
    try {
      CopyFile cf =
        new CopyFile(
          "G:/javaProject/javastudy/src/io/infile.txt",
          "G:/javaProject/javastudy/src/io/outfile.txt",
          10000);
      long startTime = System.currentTimeMillis();
      cf.copy();
      System.out.println(System.currentTimeMillis() - startTime);
    } catch (Exception e) {
      System.out.println(System.err);
    }
  }
}
－－－－－－－
在main里面做缓冲区大小改变并让他拷贝100000次文件(2000多字节)，10个字节跟10000个字节都是250毫秒左右真奇怪