java nio SocketChannel 服务器端与多客户端 信息交互(聊天功能)

服务器端:

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
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.charset.Charset;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class NIOSServer {
private int port = 8888;
//解码buffer
private Charset cs = Charset.forName("gbk");
/*接受数据缓冲区*/
private static ByteBuffer sBuffer = ByteBuffer.allocate(1024);
/*发送数据缓冲区*/
private static ByteBuffer rBuffer = ByteBuffer.allocate(1024);
/*映射客户端channel */
private Map clientsMap = new HashMap();
private static Selector selector;

public NIOSServer(int port){
this.port = port;
try {
init();
} catch (Exception e) {
e.printStackTrace();
}
}
private void init() throws IOException{
/*
*启动服务器端,配置为非阻塞,绑定端口,注册accept事件
*ACCEPT事件:当服务端收到客户端连接请求时,触发该事件
*/
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false);
ServerSocket serverSocket = serverSocketChannel.socket();
serverSocket.bind(new InetSocketAddress(port));
selector = Selector.open();
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("server start on port:"+port);
}
/**
* 服务器端轮询监听,select方法会一直阻塞直到有相关事件发生或超时
*/
private void listen(){
while (true) {
try {
selector.select();//返回值为本次触发的事件数
Set selectionKeys = selector.selectedKeys();
for(SelectionKey key : selectionKeys){
handle(key);
}
selectionKeys.clear();//清除处理过的事件
} catch (Exception e) {
e.printStackTrace();
break;
}

}
}

/**
* 处理不同的事件
*/
private void handle(SelectionKey selectionKey) throws IOException {
ServerSocketChannel server = null;
SocketChannel client = null;
String receiveText=null;
int count=0;
if (selectionKey.isAcceptable()) {
/*
* 客户端请求连接事件
* serversocket为该客户端建立socket连接,将此socket注册READ事件,监听客户端输入
* READ事件:当客户端发来数据,并已被服务器控制线程正确读取时,触发该事件
*/
server = (ServerSocketChannel) selectionKey.channel();
client = server.accept();
client.configureBlocking(false);
client.register(selector, SelectionKey.OP_READ);
} else if (selectionKey.isReadable()) {
/*
* READ事件,收到客户端发送数据,读取数据后继续注册监听客户端
*/
client = (SocketChannel) selectionKey.channel();
rBuffer.clear();
count = client.read(rBuffer);
if (count > 0) {
rBuffer.flip();
receiveText = String.valueOf(cs.decode(rBuffer).array());
System.out.println(client.toString()+":"+receiveText);
dispatch(client, receiveText);
client = (SocketChannel) selectionKey.channel();
client.register(selector, SelectionKey.OP_READ);
}
}
}

/**
* 把当前客户端信息 推送到其他客户端
*/
private void dispatch(SocketChannel client,String info) throws IOException{
Socket s = client.socket();
String name = "["+s.getInetAddress().toString().substring(1)+":"+Integer.toHexString(client.hashCode())+"]";
if(!clientsMap.isEmpty()){
for(Map.Entry entry : clientsMap.entrySet()){
SocketChannel temp = entry.getValue();
if(!client.equals(temp)){
sBuffer.clear();
sBuffer.put((name+":"+info).getBytes());
sBuffer.flip();
//输出到通道
temp.write(sBuffer);
}
}
}
clientsMap.put(name, client);
}
public static void main(String[] args) throws IOException {
NIOSServer server = new NIOSServer(7777);
server.listen();
}
}



客户端,可运行启动多个:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Set;

public class NIOClient {
/*发送数据缓冲区*/
private static ByteBuffer sBuffer = ByteBuffer.allocate(1024);
/*接受数据缓冲区*/
private static ByteBuffer rBuffer = ByteBuffer.allocate(1024);
/*服务器端地址*/
private InetSocketAddress SERVER;
private static Selector selector;
private static SocketChannel client;
private static String receiveText;
private static String sendText;
private static int count=0;

public NIOClient(int port){
SERVER = new InetSocketAddress("localhost", port);
init();
}
public void init(){
try {
/*
* 客户端向服务器端发起建立连接请求
*/
SocketChannel socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
selector = Selector.open();
socketChannel.register(selector, SelectionKey.OP_CONNECT);
socketChannel.connect(SERVER);
/*
* 轮询监听客户端上注册事件的发生
*/
while (true) {
selector.select();
Set keySet = selector.selectedKeys();
for(final SelectionKey key : keySet){
handle(key);
};
keySet.clear();
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws IOException {
NIOClient client = new NIOClient(7777);
}

private void handle(SelectionKey selectionKey) throws IOException{
if (selectionKey.isConnectable()) {
/*
* 连接建立事件,已成功连接至服务器
*/
client = (SocketChannel) selectionKey.channel();
if (client.isConnectionPending()) {
client.finishConnect();
System.out.println("connect success !");
sBuffer.clear();
sBuffer.put((new Date().toLocaleString()+" connected!").getBytes());
sBuffer.flip();
client.write(sBuffer);//发送信息至服务器
/*
* 启动线程一直监听客户端输入,有信心输入则发往服务器端
* 因为输入流是阻塞的,所以单独线程监听
*/
new Thread(){
@Override
public void run() {
while(true){
try {
sBuffer.clear();
InputStreamReader input = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(input);
sendText = br.readLine();
/*
* 未注册WRITE事件,因为大部分时间channel都是可以写的
*/
sBuffer.put(sendText.getBytes());
sBuffer.flip();
client.write(sBuffer);
} catch (IOException e) {
e.printStackTrace();
break;
}
}
};
}.start();
}
//注册读事件
client.register(selector, SelectionKey.OP_READ);
} else if (selectionKey.isReadable()) {
/*
* 读事件触发
* 有从服务器端发送过来的信息,读取输出到屏幕上后,继续注册读事件
* 监听服务器端发送信息
*/
client = (SocketChannel) selectionKey.channel();
rBuffer.clear();
count=client.read(rBuffer);
if(count>0){
receiveText = new String( rBuffer.array(),0,count);
System.out.println(receiveText);
client = (SocketChannel) selectionKey.channel();
client.register(selector, SelectionKey.OP_READ);
}
}
}
}

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