java 开发语言 网络I/o编程模型4 NIo之chanel通道实现文件复制

一 各种代码操作案例

1.1 向本地文件写数据

1.代码

package com.ljf.netty.nio;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

/**

* @ClassName: WriteToLocalDemo

* @Description: TODO

* @Author: liujianfu

* @Date: 2022/05/14 16:03:05

* @Version: V1.0

**/

public class WriteToLocalDemo {

public static void main(String[] args) throws IOException {

String str="hello,中国";

String dstPath="d:/liu.txt";

//创建一个输出流

FileOutputStream fileOutputStream=new FileOutputStream(dstPath);

//通过fileOutputStream获取对应的FileChannel

FileChannel fileChannel=fileOutputStream.getChannel();

//创建一个缓冲区 ByteBuffer

ByteBuffer byteBuffer=ByteBuffer.allocate(1024);

//将str内容放到缓存中

byteBuffer.put(str.getBytes());

//对bypteBuffer进行flip

byteBuffer.flip();

//将byteBuffer数据写入到fileChannel中

fileChannel.write(byteBuffer);

fileChannel.close();

}

}

2.效果

 1.2  读取本地文件进行输出

1.代码

package com.ljf.netty.nio;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

/**

* @ClassName: ReadFromLocalDemo

* @Description: TODO

* @Author: liujianfu

* @Date: 2022/05/14 16:15:14

* @Version: V1.0

**/

public class ReadFromLocalDemo {

public static void main(String[] args) throws IOException {

File file=new File("d:/liu.txt");

//创建文件的输入流

FileInputStream fileInputStream=new FileInputStream(file);

//通过fileinputstream 获取对应的filechannel

FileChannel fileChannel=fileInputStream.getChannel();

//创建缓存区

ByteBuffer byteBuffer=ByteBuffer.allocate((int)file.length());

//将通道的数据读入到Buffer

fileChannel.read(byteBuffer);

System.out.println(new String(byteBuffer.array()));

fileChannel.close();

}

}

2.结果

1.3  实现文件的复制操作

1.代码

package com.ljf.netty.nio;

import java.io.*;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

/**

* @ClassName: FileChannel01

* @Description: TODO

* @Author: liujianfu

* @Date: 2022/05/14 16:01:41

* @Version: V1.0

**/

public class FileChannel01 {

public static void main(String[] args) throws IOException {

//读

FileInputStream fileInputStream=new FileInputStream("d:/liu.txt");

FileChannel fileChannel01=fileInputStream.getChannel();

//写

FileOutputStream fileOutputStream=new FileOutputStream("d:/liu2.txt");

FileChannel fileChanne02=fileOutputStream.getChannel();

ByteBuffer byteBuffer=ByteBuffer.allocate(1024);

//循环

while(true){

//清空buffer，防止上一次存储的数据存储，

byteBuffer.clear();

int read= fileChannel01.read(byteBuffer);

if(read==-1){

System.out.println("已经读完，退出");

break;

}

//将buffer中的数据写入到filechannel02中

byteBuffer.flip();

fileChanne02.write(byteBuffer);

}

fileChannel01.close();

fileChanne02.close();

System.out.println("结束......");

}

}

2.结果

 1.4  使用transferFrom实现文件的复制操作

1.代码

package com.ljf.netty.nio;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.nio.channels.FileChannel;

/**

* @ClassName: TransferFileDemo

* @Description: TODO

* @Author: liujianfu

* @Date: 2022/05/14 16:55:18

* @Version: V1.0

**/

public class TransferFileDemo {

public static void main(String[] args) throws IOException {

FileInputStream fileInputStream=new FileInputStream("d:/liu.txt");

FileOutputStream fileOutputStream=new FileOutputStream("d:/liu3.txt");

//获取各个流对应的filechannel

FileChannel sourceCh=fileInputStream.getChannel();

FileChannel destCh=fileOutputStream.getChannel();

//使用transferFrom完成复制

destCh.transferFrom(sourceCh,0,sourceCh.size());

//关闭通道

sourceCh.close();

destCh.close();

fileInputStream.close();

fileOutputStream.close();

}

}

2.结果

 1.5  通过使用多个buffer完成读写操作

//Scattering:将数据写入到buffer时，可以采用buffer数组，依次写入【分散】

//Gathering: 从buffer读取数据时，可以采用buffer数组，依次读

1.代码

package com.ljf.netty.nio;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.nio.ByteBuffer;

import java.nio.channels.ServerSocketChannel;

import java.nio.channels.SocketChannel;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.stream.Collectors;

/**

* @ClassName: BacthCopy

* @Description: TODO

* @Author: liujianfu

* @Date: 2022/05/14 18:09:38

* @Version: V1.0

**/

public class BacthCopy {

public static void main(String[] args) throws IOException {

//Scattering:将数据写入到buffer时，可以采用buffer数组，依次写入【分散】

//Gathering: 从buffer读取数据时，可以采用buffer数组，依次读

//使用 ServerSocketChannel和socketChannel网络

ServerSocketChannel serverSocketChannel=ServerSocketChannel.open();

InetSocketAddress inetSocketAddress=new InetSocketAddress(7000);

//绑定端口到socket，并启动

serverSocketChannel.socket().bind(inetSocketAddress);

//创建buffer数组

ByteBuffer[] byteBuffers=new ByteBuffer[2];

byteBuffers[0]=ByteBuffer.allocate(5);

byteBuffers[1]=ByteBuffer.allocate(3);

//等客户端连接

SocketChannel socketChannel=serverSocketChannel.accept();

int messageLenght=8;

//循环读取

while(true){

int byteRead=0;

while(byteRead

long l=socketChannel.read(byteBuffers);

byteRead+=l;

System.out.println("读取字节数:"+byteRead);

Arrays.asList(byteBuffers).stream().map(bb-> "位置:"+bb.position()+" limit:"+bb.limit()).forEach(System.out::println);

List dataList=Arrays.asList(byteBuffers);

/*

List hhList= dataList.stream().map(bb-> "位置:"+bb.position()+" limit:"+bb.limit()).collect(Collectors.toList());

for(String hh:hhList){

System.out.println("jieguo:"+hh);

}

*/

}

//将所有的buffer进行flip

Arrays.asList(byteBuffers).forEach(buffer->buffer.flip());

//将数据读出，显示到客户端

long byteWirte=0;

while(byteWirte

long l=socketChannel.write(byteBuffers);

byteWirte=+l;

}

//将所有的buffer进行clear

Arrays.asList(byteBuffers).forEach(buffer->{buffer.clear();});

System.out.println("byteRead:"+byteRead+" bytewrite:"+byteWirte+"messagelength:"+messageLenght);

}

}

}

2.测试结果

cmd窗口，输入： telnet localhost 7000

按住，ctr+] 进行发送数据：

send zhongguo nihao

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