传统IO存在阻塞,CPU资源不能有效的利用。
NIO非阻塞模式,选择器(Selector)会把每一个通道Channel都注册到该Selector上,其作用是监控这些通道Channel的IO情况,再分配到服务端的线程,此间服务端可以干自己的事情,提高CPU的利用率。
package com.expgiga.NIO;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
/**
* 一、使用NIO完成网络通信的三个核心:
* 1.通道Channel:负责连接
* java.nio.channels.Channel接口:
* |--SelectableChannel
* |--SocketChannel
* |--ServerSocketChannel
* |--DatagramChannel
* <p>
* |--Pipe.SinkChannel
* |--Pipe.SourceChannel
* <p>
* 2.缓冲区Buffer:负责数据的存取
* <p>
* 3.选择器Selector:是SelectableChannel的多路复用器。用于监控SelectableChannel的IO状况。
*/
public class TestBlockingNIO {
//客户端
public void client() throws IOException {
//1.获取通道
SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("123.0.0.1", 9898));
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
//2.分配指定大小的缓冲区域
ByteBuffer buf = ByteBuffer.allocate(1024);
//3.读取本地文件,并发送到服务端去
while (inChannel.read(buf) != -1) {
buf.flip();
sChannel.write(buf);
buf.clear();
}
//4.关闭通道
inChannel.close();
sChannel.close();
}
//服务端
public void server() throws IOException {
//1.获取通道
ServerSocketChannel ssChannel = ServerSocketChannel.open();
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);
//2.绑定连接
ssChannel.bind(new InetSocketAddress(9898));
//3.获取客户端连接的通道
SocketChannel sChannel = ssChannel.accept();
//4.分配一个指定大小的缓冲区
ByteBuffer buf = ByteBuffer.allocate(1024);
//5.接受客户端的数据,保存到本地
while (sChannel.read(buf) != -1) {
buf.flip();
outChannel.write(buf);
buf.clear();
}
//6.关闭通道
sChannel.close();
outChannel.close();
ssChannel.close();
}
}
package com.expgiga.NIO;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
/**
*
*/
public class TestBlockingNIO2 {
//客户端
public void client() throws IOException {
SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));
FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
ByteBuffer buf = ByteBuffer.allocate(1024);
while (inChannel.read(buf) != -1) {
buf.flip();
sChannel.write(buf);
buf.clear();
}
sChannel.shutdownOutput();
//接受服务端的反馈
int len = 0;
while (sChannel.read(buf) != -1) {
buf.flip();
System.out.println(new String(buf.array(), 0, len));
buf.clear();
}
inChannel.close();
sChannel.close();
}
//服务端
public void server() throws IOException {
ServerSocketChannel ssChannel = ServerSocketChannel.open();
FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);
ssChannel.bind(new InetSocketAddress(9898));
SocketChannel sChannel = ssChannel.accept();
ByteBuffer buf = ByteBuffer.allocate(1024);
while (sChannel.read(buf) != -1) {
buf.flip();
outChannel.write(buf);
buf.clear();
}
//发送反馈给客户端
buf.put("服务端接受客户端数据成功".getBytes());
buf.flip();
sChannel.write(buf);
sChannel.close();
outChannel.close();
ssChannel.close();
}
}