JAVANIO通道

package com.nio.test;

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;

import java.nio.channels.FileChannel.MapMode;

import java.nio.file.Paths;

import java.nio.file.StandardOpenOption;

import org.junit.Test;

/**

 *

 * @author fliay

 *

 *         一、通道(channel): 用于源节点与目标节点的连接。在JavaNIO中负责缓冲区中数据的传输。

 *         Channel本身不存在存数据，因此需要配合缓冲区进行传输。

 *

 *         二、通道的主要实体类

 *          |--FileChannel

 *          |--SocketChannel

 *          |--ServerSocketChannel

 *          |--DatagramChannel

 *

 *         三、获取通道 1.Java针对支持通道的类提供了getChannel()方法 本地IO:

 *         FileInputStream/FileOutputStream RandomAccessFile

 *

 *         网络IO

 *          |--Socket

 *          |--ServerSocket

 *          |--DatagramSocket

 *

 *         2.在JDK1.7中的NIO.2针对各个通道提供了静态方法open()

 *         3.在JDK1.7中的NIO.2的file工具类的newByteChannel()

 *

 *         四、通道之间的数据传输

 *         	transferFrom()

 *         	transferTo()

 *

 *         五、分散(Scatter)与聚集()

 *

 */

public class TestChannel {

	// 利用通道完成文件的复制

	@Test

	public void test1() {

		long start = System.currentTimeMillis();

		FileInputStream fis = null;

		FileOutputStream fos = null;

		FileChannel inChannel = null;

		FileChannel outChannel = null;

		try {

			// cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408 大小为3.42G

			fis = new FileInputStream("/虚拟机/cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso");

			fos = new FileOutputStream("/开发/cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso");

			// 1.获取通道

			inChannel = fis.getChannel();

			outChannel = fos.getChannel();

			// 2.分配指定大小的缓冲区

			ByteBuffer buf = ByteBuffer.allocate(1024);

			// 3.将通道中的数据存入缓冲区中

			while (inChannel.read(buf) != -1) {

				// 切换到读取数据模式

				buf.flip();

				// 4.将缓冲区中的数据写入通道中

				outChannel.write(buf);

				// 情况缓冲区

				buf.clear();

			}

		} catch (FileNotFoundException e) {

			// TODO Auto-generated catch block

			e.printStackTrace();

		} catch (IOException e) {

			// TODO Auto-generated catch block

			e.printStackTrace();

		} finally {

			try {

				outChannel.close();

				inChannel.close();

				fos.close();

				fis.close();

			} catch (IOException e) {

				// TODO Auto-generated catch block

				e.printStackTrace();

			}

		}

		long end = System.currentTimeMillis();

		System.out.println("消耗时间为：" + (end - start));

	}

	// 消耗时间为：12651

	// 使用直接缓冲区完成文件的复制（内存映射文件）

	@Test

	public void Test2() throws IOException {

		long start = System.currentTimeMillis();

		FileChannel inChannel = FileChannel.open(Paths.get("/虚拟机/cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso"),

				StandardOpenOption.READ);

		FileChannel outChannel = FileChannel.open(Paths.get("/开发/cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso"),

				StandardOpenOption.WRITE, StandardOpenOption.READ, StandardOpenOption.CREATE);

		// long[] sizes = new long[3];

		// 如果文件过长的话会报错 Size exceeds Integer.MAX_VALUE 可以通过对文件进行分批存

		// sizes[0]=0;

		// sizes[1]=inChannel.size()/2;

		// sizes[2]=inChannel.size()-inChannel.size()/2;

		// for(int i=0;i<sizes.length-1;i++){

		// //内存映射文件

		// MappedByteBuffer inMappedBuf = inChannel.map(MapMode.READ_ONLY,

		// sizes[i],sizes[i+1]);

		// MappedByteBuffer outMappedBuf = outChannel.map(MapMode.READ_WRITE,

		// sizes[i],sizes[i+1]);

		// //直接对缓冲区进行数据的读写操作

		// byte[] dst = new byte[inMappedBuf.limit()];

		// inMappedBuf.get(dst);

		// outMappedBuf.put(dst);

		// }

		// 内存映射文件

		MappedByteBuffer inMappedBuf = inChannel.map(MapMode.READ_ONLY, 0, inChannel.size());

		MappedByteBuffer outMappedBuf = outChannel.map(MapMode.READ_WRITE, 0, inChannel.size());

		// 直接对缓冲区进行数据的读写操作

		byte[] dst = new byte[inMappedBuf.limit()];

		inMappedBuf.get(dst);

		outMappedBuf.put(dst);

		inChannel.close();

		outChannel.close();

		long end = System.currentTimeMillis();

		System.out.println("消耗时间为：" + (end - start));

	}// 执行时间6161

	// 通道之间的数据传输

	@Test

	public void Test3() throws IOException {

		long start = System.currentTimeMillis();

		FileChannel inChannel = FileChannel.open(Paths.get("/虚拟机/cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso"),

				StandardOpenOption.READ);

		FileChannel outChannel = FileChannel.open(Paths.get("/开发/cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso"),

				StandardOpenOption.WRITE, StandardOpenOption.READ, StandardOpenOption.CREATE);

		// inChannel.transferTo(0, inChannel.size(), outChannel);//执行时间为3957

		// 但是文件为拷贝完，只拷贝了2/3

		outChannel.transferFrom(inChannel, 0, inChannel.size());// 执行时间8313 成功拷贝

		inChannel.close();

		outChannel.close();

		long end = System.currentTimeMillis();

		System.out.println("消耗时间为：" + (end - start));

	}

	//分散和聚集

	@Test

	public void Test4() throws IOException{

		RandomAccessFile ref1 = new RandomAccessFile("/Study/JavaSite/JaveNIO/src/main/java/com/nio/test/TestChannel.java","rw");

		//1.获取通道

		FileChannel channel1 = ref1.getChannel();

		//2.分配指定大小的缓冲区

		ByteBuffer buf1 = ByteBuffer.allocate(100);

		ByteBuffer buf2 = ByteBuffer.allocate(1024);

		//3.分散读取

		ByteBuffer[] bufs ={buf1,buf2};

		channel1.read(bufs);

		for(ByteBuffer byteBuffer:bufs){

			byteBuffer.flip();

		}

		System.out.println(new String(bufs[0].array(),0,bufs[0].limit()));

		System.out.println("----------------------------------------");

		System.out.println(new String(bufs[1].array(),0,bufs[1].limit()));

		//4.聚集写入

		RandomAccessFile ref2 = new RandomAccessFile("/Study/JavaSite/JaveNIO/src/main/java/com/nio/test/TestChannel2.java","rw");

		FileChannel channel2 = ref2.getChannel();

		channel2.write(bufs);

	}

}