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package com.flyoung;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.util.Iterator;
import java.util.Set;
import java.nio.channels.SocketChannel;
public class NIOServer {
/*标志数字*/
private static int flag = 0;
/*定义缓冲区大小*/
private static int block = 4096;
/*接收缓冲区*/
private static ByteBuffer receiveBuffer = ByteBuffer.allocate(block);
/*发送缓冲区*/
private static ByteBuffer sendBuffer = ByteBuffer.allocate(block);
/*定义Selector*/
private Selector selector;
public NIOServer(int port) throws IOException{
//打开服务器套接字通道
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
//服务器配置为非阻塞
serverSocketChannel.configureBlocking(false);
//检索与此服务器套接字通道关联的套接字
ServerSocket serverSocket = serverSocketChannel.socket();
//进行服务的绑定
serverSocket.bind(new InetSocketAddress(port));
//通过open()方法找到Selector
selector = Selector.open();
//注册到selector
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("Server Start -----8888:");
}
//监听
public void listen() throws IOException{
while(true){
//监控所有注册的 channel ，当其中有注册的 IO 操作可以进行时，该函数返回，并将对应的 SelectionKey 加入 selected-key set
selector.select();
//Selected-key set 代表了所有通过 select() 方法监测到可以进行 IO 操作的 channel ，这个集合可以通过 selectedKeys() 拿到
Set<SelectionKey> selectionKeys = selector.selectedKeys();
Iterator<SelectionKey> iterator = selectionKeys.iterator();
while(iterator.hasNext()){
SelectionKey selectionKey = iterator.next();
handleKey(selectionKey);
iterator.remove();
}
}
}
//处理请求
public void handleKey(SelectionKey selectionKey) throws IOException{
//接受请求
ServerSocketChannel serverSocketChannel = null;
SocketChannel socketChannel = null;
String receiveText;
String sendText;
int count;
//测试此键的通道是否准备好接受新的套接字连接
if(selectionKey.isAcceptable()){
//返回创建此键的通道
serverSocketChannel = (ServerSocketChannel)selectionKey.channel();
//接受客户端建立连接的请求，并返回 SocketChannel 对象
socketChannel = serverSocketChannel.accept();
//配置为非阻塞
socketChannel.configureBlocking(false);
//注册到selector
socketChannel.register(selector, SelectionKey.OP_READ);
}else if(selectionKey.isReadable()){
//返回为之创建此键的通道
socketChannel = (SocketChannel)selectionKey.channel();
//将缓冲区清空，以备下次读取
receiveBuffer.clear();
//将发送来的数据读取到缓冲区
count = socketChannel.read(receiveBuffer);
if(count>0){
receiveText = new String(receiveBuffer.array(),0,count);
System.out.println("服务器端接受到的数据---"+receiveText);
socketChannel.register(selector, SelectionKey.OP_WRITE);
}
}else if (selectionKey.isWritable()) {
//将缓冲区清空以备下次写入
sendBuffer.clear();
// 返回为之创建此键的通道。
socketChannel = (SocketChannel) selectionKey.channel();
sendText="message from server--" + flag++;
//向缓冲区中输入数据
sendBuffer.put(sendText.getBytes());
//将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位
sendBuffer.flip();
//输出到通道
socketChannel.write(sendBuffer);
System.out.println("服务器端向客户端发送数据--："+sendText);
socketChannel.register(selector, SelectionKey.OP_READ);
}
}
public static void main(String[] args) throws IOException {
int port = 8888;
NIOServer server = new NIOServer(port);
server.listen();
}
}
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