java IO和NIO测试

测试环境：cpu:Q9500 4核    频率2.83GHZ      内存4G   文件大小200M

 

测试代码

 

package com.lottery;

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

public class CopyFile {
	public static void main(String[] args) throws Exception {
		readWriteFileByNio();
		readWriteFileByNioTransferTo();
		readWriteByIo();
	}

	public static void readWriteFileByNio() throws Exception {
		Long startTime = System.currentTimeMillis();

		String inFile = "D:/lottery.log4j";
		String outFile = "d:/test/1";
		FileChannel fcin = new FileInputStream(inFile).getChannel();
		FileChannel fcout = new FileOutputStream(outFile).getChannel();
		ByteBuffer buffer = ByteBuffer.allocate(1024);
		while (true) {
			buffer.clear();
			int r = fcin.read(buffer);
			if (r == -1) {
				break;
			}
			buffer.flip();
			fcout.write(buffer);
		}
		fcin.close();
		fcout.close();

		Long endTime = System.currentTimeMillis();
		System.out.println("readWriteFileByNio：" + (endTime - startTime));
	}

	public static void readWriteFileByNioTransferTo() throws Exception {
		Long startTime = System.currentTimeMillis();
		String inFile = "D:/lottery.log4j";
		String outFile = "d:/test/2";
		FileChannel fcin = new FileInputStream(inFile).getChannel();
		FileChannel fcout = new FileOutputStream(outFile).getChannel();

		fcin.transferTo(0, fcin.size(), fcout);
		fcin.close();
		fcout.close();

		Long endTime = System.currentTimeMillis();
		System.out.println("readWriteFileByNioTransferTo：" + (endTime - startTime));
	}

	public static void readWriteByIo() throws FileNotFoundException {
		Long startTime = System.currentTimeMillis();
		String inFile = "D:/lottery.log4j";
		String outFile = "d:/test/3";
		BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream(outFile));
		BufferedInputStream is = new BufferedInputStream(new FileInputStream(inFile));
		byte[] buffer = new byte[1024];
		try {
			while (is.read(buffer) != -1) {
				os.write(buffer);
			}
			os.close();
			is.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
		Long endTime = System.currentTimeMillis();
		System.out.println("readWriteByIo：" + (endTime - startTime));
	}
}

 

测试结果：

readWriteFileByNio：3453

readWriteFileByNioTransferTo：1323

readWriteByIo：791

 

结论：此测试数据还是不是很充分，没有通过多个文件大小比较。但是单单从这一个测试结果来看使用Buffer的IO性能要大大好于NIO，不使用Buffer的IO和NIO性能差距不大

其实以我看来NIO文件操作的优势不再于全文件的读写，而在于可以随意访问文件块

另外NIO在网络上面提供了非阻塞读写。