基于NIO的简易群聊系统
服务器端 (最下面有NIO的使用demo)
package me.jar.nio.groupchat; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SelectableChannel; 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.Iterator; import java.util.Set; /** * @Description * @Date 2021/1/24-22:45 */ public class GroupCharServer { private Selector selector; private ServerSocketChannel serverSocketChannel; private static final int PORT = 8889; public GroupCharServer() { try { selector = Selector.open(); serverSocketChannel = ServerSocketChannel.open(); serverSocketChannel.configureBlocking(false); serverSocketChannel.socket().bind(new InetSocketAddress(PORT)); serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT); } catch (IOException e) { System.out.println("服务器启动失败!" + e.getMessage()); } } public void listen() { try { while (true) { int count = selector.select(2000L); if (count == 0) { continue; } Iterator<SelectionKey> iterator = selector.selectedKeys().iterator(); while (iterator.hasNext()) { SelectionKey selectionKey = iterator.next(); if (selectionKey.isAcceptable()) { SocketChannel socketChannel = serverSocketChannel.accept(); socketChannel.configureBlocking(false); System.out.println("【" + socketChannel.getRemoteAddress() + "】上线了>>>"); socketChannel.register(selector, SelectionKey.OP_READ); } if (selectionKey.isReadable()) { SocketChannel channel = (SocketChannel) selectionKey.channel(); ByteBuffer byteBuffer = ByteBuffer.allocate(1024); int length = 0; try { length = channel.read(byteBuffer); String message = "【" + channel.getRemoteAddress() + "】说->" + new String(byteBuffer.array(), 0, length, Charset.forName("UTF-8")); System.out.println(message); sendToOthers(channel, message); } catch (IOException e) { System.out.println("【" + channel.getRemoteAddress() + "】离线了..."); selectionKey.cancel(); channel.close(); } } iterator.remove(); } } } catch (IOException e) { e.printStackTrace(); } } private void sendToOthers(SocketChannel channel, String message) throws IOException { // 转发消息到其他客户端 Set<SelectionKey> keys = selector.keys(); for (SelectionKey key : keys) { SelectableChannel selectableChannel = key.channel(); if (selectableChannel instanceof SocketChannel && selectableChannel != channel) { SocketChannel socketChannel = (SocketChannel) selectableChannel; ByteBuffer messageToSend = ByteBuffer.wrap(message.getBytes(Charset.forName("UTF-8"))); socketChannel.write(messageToSend); } } } public static void main(String[] args) { GroupCharServer server = new GroupCharServer(); server.listen(); } }
客户端
package me.jar.nio.groupchat; import java.io.IOException; import java.net.InetSocketAddress; import java.net.SocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; import java.util.Iterator; import java.util.Scanner; /** * @Description * @Date 2021/1/24-23:33 */ public class GroupChatClient { private static final String HOST_NAME = "127.0.0.1"; private static final int HOST_PORT = 8889; private Selector selector; private SocketChannel socketChannel; public GroupChatClient() { try { selector = Selector.open(); socketChannel = SocketChannel.open(); socketChannel.configureBlocking(false); socketChannel.connect(new InetSocketAddress(HOST_NAME, HOST_PORT)); while (!socketChannel.finishConnect()) { System.out.println("连接正在建立..."); } socketChannel.register(selector, SelectionKey.OP_READ); } catch (IOException e) { System.out.println("客户端启动失败!" + e.getMessage()); } } public void run() { new Thread(() -> { Scanner scanner = new Scanner(System.in); while (scanner.hasNext()) { String line = scanner.nextLine(); ByteBuffer byteBuffer = ByteBuffer.wrap(line.getBytes(Charset.forName("UTF-8"))); try { socketChannel.write(byteBuffer); SocketAddress localAddress = socketChannel.getLocalAddress(); System.out.println("【" + line + "】已发送!你的地址->" + localAddress); } catch (IOException e) { System.out.println("消息发送失败!" + e.getMessage()); } } }).start(); try { while (true) { int count = selector.select(2000L); if (count == 0) { continue; } Iterator<SelectionKey> iterator = selector.selectedKeys().iterator(); while (iterator.hasNext()) { SelectionKey selectionKey = iterator.next(); if (selectionKey.isReadable()) { ByteBuffer byteBuffer = ByteBuffer.allocate(1024); SocketChannel socketChannel = (SocketChannel) selectionKey.channel(); int length = 0; try { length = socketChannel.read(byteBuffer); } catch (IOException e) { System.out.println("服务端断开了..." + e.getMessage()); } System.out.println(new String(byteBuffer.array(), 0, length, Charset.forName("UTF-8"))); } iterator.remove(); } } }catch (IOException e) { System.out.println("连接断开..." + e.getMessage()); } } public static void main(String[] args) { GroupChatClient client = new GroupChatClient(); client.run(); } }
NIO的使用demo
服务器端
package me.jar.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.nio.charset.Charset; import java.util.Iterator; import java.util.Set; /** * @Description * @Date 2021/1/24-16:28 */ public class NIOServer { public static void main(String[] args) throws IOException { // 创建ServerSocketChannel对象 ServerSocketChannel serverSocketChannel = ServerSocketChannel.open(); // 创建一个Selector对象 Selector selector = Selector.open(); // 绑定一个端口,在服务器端监听 serverSocketChannel.socket().bind(new InetSocketAddress(6666)); // 设置为非阻塞(这步很重要也很容易忽略)! serverSocketChannel.configureBlocking(false); // 把ServerSocketChannel注册到Selector中,关注的事件是OP_ACCEPT serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT); // 循环等待客户端连接 while (true) { // 没有事件发生。等待一秒,如果没有事件发生,continue if (selector.select(1000L) == 0) { System.out.println("服务器等待了1秒,无连接"); continue; } // 如果返回>0,能获取到相关的SelectionKey集合,表示已经获取到关注的事件 // 通过selectionKey反向获取通道 Set<SelectionKey> selectionKeys = selector.selectedKeys(); Iterator<SelectionKey> iterator = selectionKeys.iterator(); while (iterator.hasNext()) { // 获取selectionKey SelectionKey selectionKey = iterator.next(); // 根据selectionKey,对应的通道发生的事件做相应处理 if (selectionKey.isAcceptable()) { // 如果是OP_ACCEPT,有新的客户端连接 // 在该客户端生成一个SocketChannel SocketChannel socketChannel = serverSocketChannel.accept(); System.out.println("客户端连接成功,生成了一个socketChannel->" + socketChannel.hashCode()); // 设置为非阻塞 socketChannel.configureBlocking(false); // 将socketChannel注册到selector,关注事件为OP_READ,同时给socketChannel关联一个Buffer socketChannel.register(selector, SelectionKey.OP_READ, ByteBuffer.allocate(1024)); } if (selectionKey.isReadable()) { // 发生OP_READ // 通过selectionKey,反向获取对应Channel SocketChannel socketChannel = (SocketChannel) selectionKey.channel(); // 获取到该channel关联的buffer ByteBuffer byteBuffer = (ByteBuffer) selectionKey.attachment(); int length = 0; try { length = socketChannel.read(byteBuffer); } catch (IOException e) { System.out.println("客户端可能已经断开!"); selectionKey.cancel(); } if (length > 0) { System.out.println("from 客户端:" + new String(byteBuffer.array(), 0, length, Charset.forName("UTF-8"))); } } // 手动从集合中移除当前的selectionKey,防止重复操作 iterator.remove(); } } } }
客户端
package me.jar.nio; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SocketChannel; import java.nio.charset.Charset; /** * @Description * @Date 2021/1/24-16:55 */ public class NIOClient { public static void main(String[] args) { try { // 得到一个网络通道 SocketChannel socketChannel = SocketChannel.open(); // 设置非阻塞 socketChannel.configureBlocking(false); // 提供服务器端的ip和端口 boolean connect = socketChannel.connect(new InetSocketAddress("127.0.0.1", 6666)); if (!connect) { while (!socketChannel.finishConnect()) { System.out.println("因为连接需要时间,客户端不会阻塞,可以做其他事情...."); } } // 如果连接成功,就发送数据 String words = "哈哈,让我们学习NIO吧"; // 将字符串放到buffer中 ByteBuffer byteBuffer = ByteBuffer.wrap(words.getBytes(Charset.forName("UTF-8"))); // 发送数据给服务端 socketChannel.write(byteBuffer); } catch (IOException e) { e.printStackTrace(); } } }