使用NIO实现聊天室
程序员文章站
2022-05-06 18:12:20
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服务端
package example;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
public class GroupChatServer {
private Selector selector;
private ServerSocketChannel listenChannel;
private static final int PORT = 80;
/**
* 构造器
* 初始化任务
*/
public GroupChatServer(){
try {
// 得到选择器
selector = Selector.open();
// serverSocketChannel
listenChannel = ServerSocketChannel.open();
// 绑定端口
listenChannel.socket().bind(new InetSocketAddress(PORT));
// 设置非阻塞模式
listenChannel.configureBlocking(false);
// 将该listenChannel 注册到Selector
listenChannel.register(selector, SelectionKey.OP_ACCEPT);
}catch (IOException e){
e.printStackTrace();
}
}
/**
* 监听
*/
public void listen(){
try {
// 循环处理
while (true){
int count = selector.select();
//System.out.println("**系统通知**:当前线程被唤醒!");
if (count > 0){ // 有事件处理
// 遍历得到的selectionKey集合
Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()){
// 取出selectionKey
SelectionKey key = iterator.next();
// 监听到OP_ACCEPT
if (key.isAcceptable()){
SocketChannel sc = listenChannel.accept();
sc.configureBlocking(false);
// 将该socketChannel注册到Selector
sc.register(selector, SelectionKey.OP_READ);
// 提示
System.out.println(sc.getRemoteAddress() + " connected to the chat");
//
sc.write(ByteBuffer.wrap(("您好," + sc.getRemoteAddress() + ",欢迎来到聊天室~~~").getBytes()));
}
// 通道可读
if (key.isReadable()){
// TODO处理读
readData(key);
}
// 当前的key删除, 防止重复处理
iterator.remove();
}
}
}
}catch (Exception e){
e.printStackTrace();
}
}
/**
* 读取客户端消息
* @param key
*/
private void readData(SelectionKey key){
// 定义一个SocketChannel
SocketChannel channel = null;
String msg = null;
try {
// 得到channel
channel = (SocketChannel) key.channel();
// 创建缓冲buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
int count = channel.read(buffer);
// 根据count的值做处理
if (count > 0){
// 把缓冲区数据转为字符串并输出
msg = new String(buffer.array());
// 输出该消息
System.out.println("from Client: " + msg);
}
} catch (IOException e){
try {
msg = "**系统通知:**" + channel.getRemoteAddress() + " is offline";
// 输出该消息
System.out.println(msg);
// 取消注册
key.cancel();
// 关闭通道
channel.close();
} catch (IOException e1) {
e1.printStackTrace();
}
} finally {
try {
sendInfoToAllClients(msg);
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 广播消息给所有客户端(channel)
* @param msg
*/
private void sendInfoToAllClients(String msg) throws IOException {
// 遍历, 所有注册到selector上的SocketChannel
for (SelectionKey key : selector.keys()){
// 通过key取出对应的SocketChannel
Channel targetChannel = key.channel();
if (targetChannel instanceof SocketChannel && targetChannel.isOpen()){
// 转型
SocketChannel dest = (SocketChannel) targetChannel;
// 将消息存储到buffer
ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
// 将buffer数据写入到通道
dest.write(buffer);
}
}
}
public static void main(String[] args) {
// 创建服务器对象
GroupChatServer groupChatServer = new GroupChatServer();
groupChatServer.listen();
}
}
客户端
package example;
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.SocketChannel;
import java.util.Iterator;
import java.util.Scanner;
public class GroupChatClient {
// 定义相关属性
private final int PORT = 80;
private Selector selector;
private SocketChannel socketChannel;
private java.lang.String username;
/**
* 构造器, 完成初始化工作
*/
public GroupChatClient() throws IOException {
selector = Selector.open();
// 连接服务器
socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", PORT));
// 设置非阻塞
socketChannel.configureBlocking(false);
// 将channel 注册到selector
socketChannel.register(selector, SelectionKey.OP_READ);
// 得到username
username = socketChannel.getLocalAddress().toString().substring(1);
System.out.println(username + " is fine");
}
/**
* 向服务器发送消息
* @param info
*/
public void sendInfo(String info){
info = username + " said: " + info;
try {
socketChannel.write(ByteBuffer.wrap(info.getBytes()));
} catch (IOException e) {
e.printStackTrace();
}
}
public void readInfo(){
try{
int readChannels = selector.select();
//System.out.println("**系统通知**:当前线程被唤醒!");
// 有可用的通道
if (readChannels > 0){
Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()){
SelectionKey key = iterator.next();
// 客户端只考虑可读
if (key.isReadable()){
// 得到相关通道
SocketChannel sc = (SocketChannel) key.channel();
// 得到一个Buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
// 读取
sc.read(buffer);
// 把读到的缓冲区数据转成字符串
String msg = new String(((buffer.array())));
//String msg = getString(buffer);
System.out.println(msg.trim());
}
}
iterator.remove(); // 删除当前的selectionKey, 防止重复操作
} else {
System.out.println("No channel available");
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws IOException {
// 启动客户端
GroupChatClient chaClient = new GroupChatClient();
// 启动一个线程
new Thread(){
@Override
public void run() {
while (true){
chaClient.readInfo();
}
}
}.start();
// 发送数据给服务器端
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()){
String s = scanner.nextLine();
chaClient.sendInfo(s);
}
}
}
参考资料
[01] NIO SelectionKey.cancel只对下一次select()生效?
[02] Java NIO开发需要注意的陷阱
[03] NIO网络编程实战之简单多人聊天室
[04] NIO 聊天室代码实现
[05] Java NIO示例:多人网络聊天室
[06] Java NIO实战之聊天室
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