package io.NIO;

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;

import java.util.Set;

public class MyNioServer {

private Selector selector; //创建一个选择器

private final static int port = 8686;

private final static int BUF_SIZE = 10240;

private void initServer() throws IOException {

//创建通道管理器对象selector

this.selector = Selector.open();

//创建一个通道对象channel

ServerSocketChannel channel = ServerSocketChannel.open();

channel.configureBlocking(false); //将通道设置为非阻塞

channel.socket().bind(new InetSocketAddress(port)); //将通道绑定在8686端口

//将上述的通道管理器和通道绑定，并为该通道注册OP_ACCEPT事件

//注册事件后，当该事件到达时，selector.select()会返回（一个key），如果该事件没到达selector.select()会一直阻塞

SelectionKey selectionKey = channel.register(selector, SelectionKey.OP_ACCEPT);

while (true) { //轮询

selector.select(); //这是一个阻塞方法，一直等待直到有数据可读，返回值是key的数量（可以有多个）

Set keys = selector.selectedKeys(); //如果channel有数据了，将生成的key访入keys集合中

Iterator iterator = keys.iterator(); //得到这个keys集合的迭代器

while (iterator.hasNext()) { //使用迭代器遍历集合

SelectionKey key = (SelectionKey) iterator.next(); //得到集合中的一个key实例

iterator.remove(); //拿到当前key实例之后记得在迭代器中将这个元素删除，非常重要，否则会出错

if (key.isAcceptable()) { //判断当前key所代表的channel是否在Acceptable状态，如果是就进行接收

doAccept(key);

} else if (key.isReadable()) {

doRead(key);

} else if (key.isWritable() && key.isValid()) {

doWrite(key);

} else if (key.isConnectable()) {

System.out.println("连接成功！");

}

}

}

}

public void doAccept(SelectionKey key) throws IOException {

ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();

System.out.println("ServerSocketChannel正在循环监听");

SocketChannel clientChannel = serverChannel.accept();

clientChannel.configureBlocking(false);

clientChannel.register(key.selector(), SelectionKey.OP_READ);

}

public void doRead(SelectionKey key) throws IOException {

SocketChannel clientChannel = (SocketChannel) key.channel();

ByteBuffer byteBuffer = ByteBuffer.allocate(BUF_SIZE);

long bytesRead = clientChannel.read(byteBuffer);

while (bytesRead > 0) {

byteBuffer.flip();

byte[] data = byteBuffer.array();

String info = new String(data).trim();

System.out.println("从客户端发送过来的消息是：" + info);

byteBuffer.clear();

bytesRead = clientChannel.read(byteBuffer);

}

if (bytesRead == -1) {

clientChannel.close();

}

}

public void doWrite(SelectionKey key) throws IOException {

ByteBuffer byteBuffer = ByteBuffer.allocate(BUF_SIZE);

byteBuffer.flip();

SocketChannel clientChannel = (SocketChannel) key.channel();

while (byteBuffer.hasRemaining()) {

clientChannel.write(byteBuffer);

}

byteBuffer.compact();

}

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

MyNioServer myNioServer = new MyNioServer();

myNioServer.initServer();

}

}