还记得之前介绍NIO时对比传统IO的一大特点吗?就是NIO是非阻塞式的,这篇文章带大家来看一下非阻塞的网络操作。
补充:以数组的形式使用缓冲区
package testnio;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class TestBufferArray {
public static void main(String[] args) throws IOException {
RandomAccessFile raf1=new RandomAccessFile("D:/1.txt","rw");
//1.获取通道
FileChannel channel1=raf1.getChannel();
//2.创建缓冲区数组
ByteBuffer buf1=ByteBuffer.allocate(512);
ByteBuffer buf2=ByteBuffer.allocate(512);
ByteBuffer[] bufs= {buf1,buf2};
//3.将数据读入缓冲区数组
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()));
//写入缓冲区数组到通道中
RandomAccessFile raf2=new RandomAccessFile("D:/2.txt","rw");
FileChannel channel2=raf2.getChannel();
channel2.write(bufs);
}
}
使用NIO实现阻塞式网络通信
TCP协议的网络通信传统实现方式是通过套接字编程(Socket和ServerSocket),NIO实现TCP网络通信需要用到 Channel 接口的两个实现类:SocketChannel和ServerSocketChannel
使用NIO实现阻塞式网络通信
客户端
package com.jikedaquan.blockingnio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
public class Client {
public static void main(String[] args) {
SocketChannel sChannel=null;
FileChannel inChannel=null;
try {
//1、获取通道
sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 1666));
//用于读取文件
inChannel = FileChannel.open(Paths.get("F:/a.jpg"), StandardOpenOption.READ);
//2、分配指定大小的缓冲区
ByteBuffer buf=ByteBuffer.allocate(1024);
//3、读取本地文件,发送到服务器端
while(inChannel.read(buf)!=-1) {
buf.flip();
sChannel.write(buf);
buf.clear();
}
} catch (IOException e) {
e.printStackTrace();
}finally {
//关闭通道
if (inChannel!=null) {
try {
inChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(sChannel!=null) {
try {
sChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
new InetSocketAddress("127.0.0.1", 1666) 用于向客户端套接字通道(SocketChannel)绑定要连接地址和端口
服务端
package com.jikedaquan.blockingnio;
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 Server {
public static void main(String[] args) {
ServerSocketChannel ssChannel=null;
FileChannel outChannel=null;
SocketChannel sChannel=null;
try {
//1、获取通道
ssChannel = ServerSocketChannel.open();
//用于保存文件的通道
outChannel = FileChannel.open(Paths.get("F:/b.jpg"), StandardOpenOption.WRITE,StandardOpenOption.CREATE);
//2、绑定要监听的端口号
ssChannel.bind(new InetSocketAddress(1666));
//3、获取客户端连接的通道
sChannel = ssChannel.accept();
//4、分配指定大小的缓冲区
ByteBuffer buf=ByteBuffer.allocate(1024);
//5、接收客户端的数据,并保存到本地
while(sChannel.read(buf)!=-1) {
buf.flip();
outChannel.write(buf);
buf.clear();
}
} catch (IOException e) {
e.printStackTrace();
}finally {
//6、关闭通道
if(sChannel!=null) {
try {
sChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(outChannel!=null) {
try {
outChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(ssChannel!=null) {
try {
ssChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
服务端套接字仅绑定要监听的端口即可
ssChannel.bind(new InetSocketAddress(1666));
上面的代码使用NIO实现的网络通信,可能有同学会问,没有看到阻塞效果啊,确实是阻塞式的看不到效果,因为客户端发送一次数据就结束了,服务端也是接收一次数据就结束了。那如果服务端接收完成数据后,再向客户端反馈呢?
能够看到阻塞效果的网络通信
客户端
package com.jikedaquan.blockingnio2;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
public class Client {
public static void main(String[] args) {
SocketChannel sChannel=null;
FileChannel inChannel=null;
try {
sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 1666));
inChannel = FileChannel.open(Paths.get("F:/a.jpg"), StandardOpenOption.READ);
ByteBuffer buf=ByteBuffer.allocate(1024);
while(inChannel.read(buf)!=-1) {
buf.flip();
sChannel.write(buf);
buf.clear();
}
//sChannel.shutdownOutput();//去掉注释掉将不会阻塞
//接收服务器端的反馈
int len=0;
while((len=sChannel.read(buf))!=-1) {
buf.flip();
System.out.println(new String(buf.array(),0,len));
buf.clear();
}
} catch (IOException e) {
e.printStackTrace();
}finally {
if(inChannel!=null) {
try {
inChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(sChannel!=null) {
try {
sChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
服务端
package com.jikedaquan.blockingnio2;
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 Server {
public static void main(String[] args) {
ServerSocketChannel ssChannel=null;
FileChannel outChannel=null;
SocketChannel sChannel=null;
try {
ssChannel = ServerSocketChannel.open();
outChannel = FileChannel.open(Paths.get("F:/a.jpg"),StandardOpenOption.WRITE,StandardOpenOption.CREATE);
ssChannel.bind(new InetSocketAddress(1666));
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("服务端接收数据成功".getBytes());
buf.flip();
sChannel.write(buf);
} catch (IOException e) {
e.printStackTrace();
}finally {
if(sChannel!=null) {
try {
sChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(outChannel!=null) {
try {
outChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(ssChannel!=null) {
try {
ssChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
服务端将向客户端发送两次数据
选择器(Selector)
想要实现非阻塞的IO,必须要先弄懂选择器。Selector 抽象类,可通过调用此类的 open 方法创建选择器,该方法将使用系统的默认选择器提供者创建新的选择器。
将通道设置为非阻塞之后,需要将通道注册到选择器中,注册的同时需要指定一个选择键的类型 (SelectionKey)。
选择键(SelectionKey)可以认为是一种标记,标记通道的类型和状态。
SelectionKey的静态字段:
OP_ACCEPT:用于套接字接受操作的操作集位
OP_CONNECT:用于套接字连接操作的操作集位
OP_READ:用于读取操作的操作集位
OP_WRITE:用于写入操作的操作集位
用于检测通道状态的方法:
方法名称 | 说明 |
---|---|
isAcceptable() | 测试此键的通道是否已准备好接受新的套接字连接 |
isConnectable() | 测试此键的通道是否已完成其套接字连接操作 |
isReadable() | 测试此键的通道是否已准备好进行读取 |
isWritable() | 测试此键的通道是否已准备好进行写入 |
将通道注册到选择器:
ssChannel.register(selector, SelectionKey.OP_ACCEPT);
IO操作准备就绪的通道大于0,轮询选择器
while(selector.select()>0) {
//获取选择键,根据不同的状态做不同的操作
}
实现非阻塞式TCP协议网络通信
非阻塞模式:channel.configureBlocking(false);
客户端
package com.jikedaquan.nonblockingnio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Scanner;
public class Client {
public static void main(String[] args) {
SocketChannel sChannel=null;
try {
//1、获取通道
sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1",1666));
//2、切换非阻塞模式
sChannel.configureBlocking(false);
//3、分配指定大小的缓冲区
ByteBuffer buf=ByteBuffer.allocate(1024);
//4、发送数据给服务端
Scanner scanner=new Scanner(System.in);
//循环从控制台录入数据发送给服务端
while(scanner.hasNext()) {
String str=scanner.next();
buf.put((new Date().toString()+"\n"+str).getBytes());
buf.flip();
sChannel.write(buf);
buf.clear();
}
} catch (IOException e) {
e.printStackTrace();
}finally {
//5、关闭通道
if(sChannel!=null) {
try {
sChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
服务端
package com.jikedaquan.nonblockingnio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
public class Server {
public static void main(String[] args) throws IOException {
//1、获取通道
ServerSocketChannel ssChannel=ServerSocketChannel.open();
//2、切换非阻塞模式
ssChannel.configureBlocking(false);
//3、绑定监听的端口号
ssChannel.bind(new InetSocketAddress(1666));
//4、获取选择器
Selector selector=Selector.open();
//5、将通道注册到选择器上,并指定“监听接收事件”
ssChannel.register(selector, SelectionKey.OP_ACCEPT);
//6、轮询式的获取选择器上已经 “准备就绪”的事件
while(selector.select()>0) {
//7、获取当前选择器中所有注册的“选择键(已就绪的监听事件)”
Iterator<SelectionKey> it=selector.selectedKeys().iterator();
while(it.hasNext()) {
//8、获取准备就绪的事件
SelectionKey sk=it.next();
//9、判断具体是什么事件准备就绪
if(sk.isAcceptable()) {
//10、若“接收就绪”,获取客户端连接
SocketChannel sChannel=ssChannel.accept();
//11、切换非阻塞模式
sChannel.configureBlocking(false);
//12、将该通道注册到选择器上
sChannel.register(selector, SelectionKey.OP_READ);
}else if(sk.isReadable()) {
//13、获取当前选择器上“读就绪”状态的通道
SocketChannel sChannel=(SocketChannel)sk.channel();
//14、读取数据
ByteBuffer buf=ByteBuffer.allocate(1024);
int len=0;
while((len=sChannel.read(buf))>0) {
buf.flip();
System.out.println(new String(buf.array(),0,len));
buf.clear();
}
}
//15、取消选择键 SelectionKey
it.remove();
}
}
}
}
服务端接收客户端的操作需要在判断 isAcceptable() 方法内将就绪的套接字通道以读操作注册到 选择器中
在判断 isReadable() 内从通道中获取数据
实现非阻塞式UDP协议网络通信
发送端
package com.jikedaquan.nonblockingnio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.util.Scanner;
public class TestDatagramSend {
public static void main(String[] args) throws IOException {
//获取通道
DatagramChannel dChannel=DatagramChannel.open();
//非阻塞
dChannel.configureBlocking(false);
ByteBuffer buf=ByteBuffer.allocate(1024);
Scanner scanner=new Scanner(System.in);
while(scanner.hasNext()) {
String str=scanner.next();
buf.put(str.getBytes());
buf.flip();
//发送数据到目标地址和端口
dChannel.send(buf,new InetSocketAddress("127.0.0.1", 1666));
buf.clear();
}
dChannel.close();
}
}
接收端
package com.jikedaquan.nonblockingnio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.Iterator;
public class TestDatagramReceive {
public static void main(String[] args) throws IOException {
//获取通道
DatagramChannel dChannel=DatagramChannel.open();
dChannel.configureBlocking(false);
//绑定监听端口
dChannel.bind(new InetSocketAddress(1666));
//获取选择器
Selector selector=Selector.open();
//读操作注册通道
dChannel.register(selector, SelectionKey.OP_READ);
while(selector.select()>0) {
Iterator<SelectionKey> it=selector.selectedKeys().iterator();
//迭代选择键
while(it.hasNext()) {
SelectionKey sk=it.next();
//通道可读
if(sk.isReadable()) {
ByteBuffer buf=ByteBuffer.allocate(1024);
//接收数据存入缓冲区
dChannel.receive(buf);
buf.flip();
System.out.println(new String(buf.array(),0,buf.limit()));
buf.clear();
}
}
it.remove();
}
}
}
原文地址:https://www.cnblogs.com/AIThink/p/9925961.html