Java NIO 网络编程

Java NIO和IO的主要区别

IO                NIO
面向流            面向缓冲
阻塞IO            非阻塞IO
无                选择器

面向流与面向缓冲

阻塞与非阻塞IO

选择器（Selectors）

NIO和IO如何影响应用程序的设计

API调用

数据处理

Name: Anna
Age: 25
Email: anna@mailserver.com
Phone: 1234567890

1

BufferedReader reader =

new

BufferedReader(

new

InputStreamReader(input));

2

3

String nameLine   = reader.readLine();

4

String ageLine    = reader.readLine();

5

String emailLine  = reader.readLine();

6

String phoneLine  = reader.readLine();

1

ByteBuffer buffer = ByteBuffer.allocate(

48

);

2

3

int

bytesRead = inChannel.read(buffer);

1

ByteBuffer buffer = ByteBuffer.allocate(

48

);

2

3

int

bytesRead = inChannel.read(buffer);

4

5

while

(! bufferFull(bytesRead) ) {

6

7

bytesRead = inChannel.read(buffer);

8

9

}

package com.example.main;

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.nio.channels.spi.SelectorProvider;
import java.util.Iterator;

/**
* TCP/IP的NIO非阻塞方式
* 服务器端
* */
public class Server implements Runnable {

//第一个端口
private Integer port1 = 8099;
//第二个端口
private Integer port2 = 9099;
//第一个服务器通道 服务A
private ServerSocketChannel serversocket1;
//第二个服务器通道 服务B
private ServerSocketChannel serversocket2;
//连接1
private SocketChannel clientchannel1;
//连接2
private SocketChannel clientchannel2;

//选择器，主要用来监控各个通道的事件
private Selector selector;

//缓冲区
private ByteBuffer buf = ByteBuffer.allocate(512);

public Server() {
init();
}

/**
* 这个method的作用
* 1：是初始化选择器
* 2：打开两个通道
* 3：给通道上绑定一个socket
* 4：将选择器注册到通道上
* */
public void init() {
try {
//创建选择器
this.selector = SelectorProvider.provider().openSelector();
//打开第一个服务器通道
this.serversocket1 = ServerSocketChannel.open();
//告诉程序现在不是阻塞方式的
this.serversocket1.configureBlocking(false);
//获取现在与该通道关联的套接字
this.serversocket1.socket().bind(new InetSocketAddress("localhost", this.port1));
//将选择器注册到通道上，返回一个选择键
//OP_ACCEPT用于套接字接受操作的操作集位
this.serversocket1.register(this.selector, SelectionKey.OP_ACCEPT);

//然后初始化第二个服务端
this.serversocket2 = ServerSocketChannel.open();
this.serversocket2.configureBlocking(false);
this.serversocket2.socket().bind(new InetSocketAddress("localhost", this.port2));
this.serversocket2.register(this.selector, SelectionKey.OP_ACCEPT);

} catch (Exception e) {
e.printStackTrace();
}

}

/**
* 这个方法是连接
* 客户端连接服务器
* @throws IOException
* */
public void accept(SelectionKey key) throws IOException {
ServerSocketChannel server = (ServerSocketChannel) key.channel();
if (server.equals(serversocket1)) {
clientchannel1 = server.accept();
clientchannel1.configureBlocking(false);
//OP_READ用于读取操作的操作集位
clientchannel1.register(this.selector, SelectionKey.OP_READ);
} else {
clientchannel2 = server.accept();
clientchannel2.configureBlocking(false);
//OP_READ用于读取操作的操作集位
clientchannel2.register(this.selector, SelectionKey.OP_READ);
}
}

/**
* 从通道中读取数据
* 并且判断是给那个服务通道的
* @throws IOException
* */
public void read(SelectionKey key) throws IOException {

this.buf.clear();
//通过选择键来找到之前注册的通道
//但是这里注册的是ServerSocketChannel为什么会返回一个SocketChannel？？
SocketChannel channel = (SocketChannel) key.channel();
//从通道里面读取数据到缓冲区并返回读取字节数
int count = channel.read(this.buf);

if (count == -1) {
//取消这个通道的注册
key.channel().close();
key.cancel();
return;
}

//将数据从缓冲区中拿出来
String input = new String(this.buf.array()).trim();
//那么现在判断是连接的那种服务
if (channel.equals(this.clientchannel1)) {
System.out.println("欢迎您使用服务A");
System.out.println("您的输入为：" + input);
} else {
System.out.println("欢迎您使用服务B");
System.out.println("您的输入为：" + input);
}

}

@Override
public void run() {
while (true) {
try {
System.out.println("running ... ");
//选择一组键，其相应的通道已为 I/O 操作准备就绪。
this.selector.select();

//返回此选择器的已选择键集
//public abstract Set<SelectionKey> selectedKeys()
Iterator selectorKeys = this.selector.selectedKeys().iterator();
while (selectorKeys.hasNext()) {
System.out.println("running2 ... ");
//这里找到当前的选择键
SelectionKey key = (SelectionKey) selectorKeys.next();
//然后将它从返回键队列中删除
selectorKeys.remove();
if (!key.isValid()) { // 选择键无效
continue;
}
if (key.isAcceptable()) {
//如果遇到请求那么就响应
this.accept(key);
} else if (key.isReadable()) {
//读取客户端的数据
this.read(key);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

public static void main(String[] args) {
Server server = new Server();
Thread thread = new Thread(server);
thread.start();
}
}

package com.example.main;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.net.InetAddress;

/**
* TCP/IP的NIO非阻塞方式
* 客户端
* */
public class Client {

//创建缓冲区
private ByteBuffer buffer = ByteBuffer.allocate(512);
//访问服务器

public void query(String host, int port) throws IOException {
InetSocketAddress address = new InetSocketAddress(InetAddress.getByName(host), port);
SocketChannel socket = null;
byte[] bytes = new byte[512];
while (true) {
try {
System.in.read(bytes);
socket = SocketChannel.open();
socket.connect(address);
buffer.clear();
buffer.put(bytes);
buffer.flip();
socket.write(buffer);
buffer.clear();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (socket != null) {
socket.close();
}
}
}
}

public static void main(String[] args) throws IOException {
new Client().query("localhost", 8099);

}
}