Java基於NIO實現群聊系統
本文實例為大傢分享瞭Java基於NIO實現群聊系統的具體代碼，供大傢參考，具體內容如下
實例要求：
1.編寫一個 NIO 群聊系統，實現服務器端和客戶端之間的數據簡單通訊（非阻塞）
2.實現多人群聊
3.服務器端：可以監測用戶上線，離線，並實現消息轉發功能
4.客戶端：通過 Channel 可以無阻塞發送消息給其它所有用戶，同時可以接受其它用戶發送的消息（有服務器轉發得到）
5.目的：進一步理解 NIO 非阻塞網絡編程機制
6.示意圖分析和代碼
// 服務端：
package com.atguigu.nio.groupchat;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.Channel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
public class GroupChatServer {
//定義屬性
private Selector selector;
private ServerSocketChannel listenChannel;
private static final int PORT = 6667;
//構造器
//初始化工作
public GroupChatServer() {
try {
//得到選擇器
selector = Selector.open();
//ServerSocketChannel
listenChannel = ServerSocketChannel.open();
//綁定端口
listenChannel.socket().bind(new InetSocketAddress(PORT));
//設置非阻塞模式
listenChannel.configureBlocking(false);
//將該 listenChannel 註冊到 selector
listenChannel.register(selector, SelectionKey.OP_ACCEPT);
} catch (IOException e) {
e.printStackTrace();
}
}
public void listen() {
try {
//循環處理
while (true) {
int count = selector.select();
if (count > 0) { //有事件處理
// 遍歷得到 selectionKey 集合
Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()) {
//取出 selectionkey
SelectionKey key = iterator.next();
//監聽到 accept
if (key.isAcceptable()) {
SocketChannel sc = listenChannel.accept();
sc.configureBlocking(false);
//將該 sc 註冊到 seletor
sc.register(selector, SelectionKey.OP_READ);
//提示
System.out.println(sc.getRemoteAddress() + " 上線 ");
}
if (key.isReadable()) {//通道發送read事件，即通道是可讀的狀態
// 處理讀(專門寫方法..)
readData(key);
}
//當前的 key 刪除，防止重復處理
iterator.remove();
}
} else {
System.out.println("等待....");
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
//發生異常處理....
}
}
//讀取客戶端消息
public void readData(SelectionKey key) {
SocketChannel channel = null;
try {
//得到 channel
channel = (SocketChannel) key.channel();
//創建 buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
int count = channel.read(buffer);
//根據 count 的值做處理
if (count > 0) {
//把緩存區的數據轉成字符串
String msg = new String(buffer.array());
//輸出該消息
System.out.println("form客戶端:" + msg);
//向其它的客戶端轉發消息(去掉自己),專門寫一個方法來處理
sendInfoToOtherClients(msg, channel);
}
} catch (IOException e) {
try {
System.out.println(channel.getRemoteAddress() + "離線瞭..");
//取消註冊
key.cancel();
//關閉通道
channel.close();
} catch (IOException e2) {
e2.printStackTrace();
}
}
}
//轉發消息給其它客戶(通道)
private void sendInfoToOtherClients(String msg, SocketChannel self) throws IOException {
System.out.println("服務器轉發消息中...");
//遍歷所有註冊到 selector 上的 SocketChannel,並排除 self
for (SelectionKey key : selector.keys()) {
//通過 key 取出對應的 SocketChannel
Channel targetChannel = key.channel();
//排除自己
if (targetChannel instanceof SocketChannel && targetChannel != self) {
//轉型
SocketChannel dest = (SocketChannel) targetChannel;
//將 msg 存儲到 buffer
ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
//將 buffer 的數據寫入通道
dest.write(buffer);
}
}
}
public static void main(String[] args) {
//創建服務器對象
GroupChatServer groupChatServer = new GroupChatServer();
groupChatServer.listen();
}
}
// 客戶端：
package com.atguigu.nio.groupchat;
~~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 {
//定義相關的屬性
private final String HOST = "127.0.0.1";//服務器的ip
private final int PORT = 6667;//服務器端口
private Selector selector;
private SocketChannel socketChannel;
private String username;
//構造器,完成初始化工作
public GroupChatClient() throws IOException {
selector = Selector.open();
//連接服務器
socketChannel = SocketChannel.open(new InetSocketAddress(HOST, PORT));
//設置非阻塞
socketChannel.configureBlocking(false);
//將 channel 註冊到selector
socketChannel.register(selector, SelectionKey.OP_READ);
//得到 username
username = socketChannel.getLocalAddress().toString().substring(1);
System.out.println(username + " is ok...");
}
//向服務器發送消息
public void sendInfo(String info) {
info = username + " 說：" + info;
try {
socketChannel.write(ByteBuffer.wrap(info.getBytes()));
} catch (IOException e) {
e.printStackTrace();
}
}
//讀取從服務器端回復的消息
public void readInfo() {
try {
int readChannels = selector.select();
if (readChannels > 0) {//有可以用的通道
Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()) {
SelectionKey key = iterator.next();
if (key.isReadable()) {
//得到相關的通道
SocketChannel sc = (SocketChannel) key.channel();
//得到一個 Buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
//讀取
sc.read(buffer);
//把讀到的緩沖區的數據轉成字符串
String msg = new String(buffer.array());
System.out.println(msg.trim());
}
}
iterator.remove(); //刪除當前的 selectionKey,防止重復操作
} else {
//System.out.println("沒有可以用的通道...");
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception {
//啟動我們客戶端
GroupChatClient chatClient = new GroupChatClient();
//啟動一個線程,每個 3 秒，讀取從服務器發送數據
new Thread() {
public void run() {
while (true) {
chatClient.readInfo();
try {
Thread.currentThread().sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}.start();
//發送數據給服務器端
Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
String s = scanner.nextLine();
chatClient.sendInfo(s);
}
}
}
運行結果
以上就是本文的全部內容，希望對大傢的學習有所幫助，也希望大傢多多支持WalkonNet。