Java NIO示例：多人網路聊天室
阿新 • • 發佈：2018-12-12
一個多客戶端聊天室，支援多客戶端聊天，有如下功能：
- 功能1： 客戶端通過Java NIO連線到服務端，支援多客戶端的連線
- 功能2：客戶端初次連線時，服務端提示輸入暱稱，如果暱稱已經有人使用，提示重新輸入，如果暱稱唯一，則登入成功，之後傳送訊息都需要按照規定格式帶著暱稱傳送訊息
- 功能3：客戶端登入後，傳送已經設定好的歡迎資訊和線上人數給客戶端，並且通知其他客戶端該客戶端上線
- 功能4：伺服器收到已登入客戶端輸入內容，轉發至其他登入客戶端。
- 功能5 TODO：客戶端下線檢測 方案是：客戶端線上的時候傳送心跳，服務端用TimeCacheMap自動刪除過期物件，同時通知線上使用者刪掉的使用者下線。
下面演示下效果，程式碼見附錄！
啟動伺服器，監聽某個埠
伺服器console
Server is listening now...
啟動一個客戶端，連線伺服器
伺服器console
Server is listening now... Server is listening from client :/127.0.0.1:50206
客戶端console
Please input your name.
客戶端輸入一個暱稱
服務端console
Server is listening now... Server is listening from client :/127.0.0.1:50206 Server is listening from client /127.0.0.1:50206 data rev is: byr1#@#
客戶端console
Please input your name. byr1 welcome byr1 to chat room! Online numbers:1
再啟動另外一個客戶端，並輸入暱稱
服務端console
Server is listening now... Server is listening from client :/127.0.0.1:50206 Server is listening from client /127.0.0.1:50206 data rev is: byr1#@# Server is listening from client :/127.0.0.1:50261 Server is listening from client /127.0.0.1:50261 data rev is: byr2#@#
客戶端byr1 console
Please input your name. byr1 welcome byr1 to chat room! Online numbers:1 welcome byr2 to chat room! Online numbers:2
客戶端byr2 console
Please input your name. byr2 welcome byr2 to chat room! Online numbers:2
客戶端byr1傳送一個訊息，客戶byr2回一條訊息
服務端console
Server is listening now... Server is listening from client :/127.0.0.1:50206 Server is listening from client /127.0.0.1:50206 data rev is: byr1#@# Server is listening from client :/127.0.0.1:50261 Server is listening from client /127.0.0.1:50261 data rev is: byr2#@# Server is listening from client /127.0.0.1:50206 data rev is: byr1#@#hello byr2, a nice day, isn't it? Server is listening from client /127.0.0.1:50261 data rev is: byr2#@#fine
客戶端byr1 console
Please input your name. byr1 welcome byr1 to chat room! Online numbers:1 welcome byr2 to chat room! Online numbers:2 hello byr2, a nice day, isn't it? byr2 say fine
客戶端byr2 console
Please input your name. byr2 welcome byr2 to chat room! Online numbers:2 byr1 say hello byr2, a nice day, isn't it? fine
附錄：server和client程式碼
server程式碼
package com.huahuiyang.channel;
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.nio.charset.Charset;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* 網路多客戶端聊天室
* 功能1： 客戶端通過Java NIO連線到服務端，支援多客戶端的連線
* 功能2：客戶端初次連線時，服務端提示輸入暱稱，如果暱稱已經有人使用，提示重新輸入，如果暱稱唯一，則登入成功，之後傳送訊息都需要按照規定格式帶著暱稱傳送訊息
* 功能3：客戶端登入後，傳送已經設定好的歡迎資訊和線上人數給客戶端，並且通知其他客戶端該客戶端上線
* 功能4：伺服器收到已登入客戶端輸入內容，轉發至其他登入客戶端。
*
* TODO 客戶端下線檢測
*/
public class ChatRoomServer {
private Selector selector = null;
static final int port = 9999;
private Charset charset = Charset.forName("UTF-8");
//用來記錄線上人數，以及暱稱
private static HashSet<String> users = new HashSet<String>();
private static String USER_EXIST = "system message: user exist, please change a name";
//相當於自定義協議格式，與客戶端協商好
private static String USER_CONTENT_SPILIT = "#@#";
private static boolean flag = false;
public void init() throws IOException
{
selector = Selector.open();
ServerSocketChannel server = ServerSocketChannel.open();
server.bind(new InetSocketAddress(port));
//非阻塞的方式
server.configureBlocking(false);
//註冊到選擇器上，設定為監聽狀態
server.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("Server is listening now...");
while(true) {
int readyChannels = selector.select();
if(readyChannels == 0) continue;
Set selectedKeys = selector.selectedKeys(); //可以通過這個方法，知道可用通道的集合
Iterator keyIterator = selectedKeys.iterator();
while(keyIterator.hasNext()) {
SelectionKey sk = (SelectionKey) keyIterator.next();
keyIterator.remove();
dealWithSelectionKey(server,sk);
}
}
}
public void dealWithSelectionKey(ServerSocketChannel server,SelectionKey sk) throws IOException {
if(sk.isAcceptable())
{
SocketChannel sc = server.accept();
//非阻塞模式
sc.configureBlocking(false);
//註冊選擇器，並設定為讀取模式，收到一個連線請求，然後起一個SocketChannel，並註冊到selector上，之後這個連線的資料，就由這個SocketChannel處理
sc.register(selector, SelectionKey.OP_READ);
//將此對應的channel設定為準備接受其他客戶端請求
sk.interestOps(SelectionKey.OP_ACCEPT);
System.out.println("Server is listening from client :" + sc.getRemoteAddress());
sc.write(charset.encode("Please input your name."));
}
//處理來自客戶端的資料讀取請求
if(sk.isReadable())
{
//返回該SelectionKey對應的 Channel，其中有資料需要讀取
SocketChannel sc = (SocketChannel)sk.channel();
ByteBuffer buff = ByteBuffer.allocate(1024);
StringBuilder content = new StringBuilder();
try
{
while(sc.read(buff) > 0)
{
buff.flip();
content.append(charset.decode(buff));
}
System.out.println("Server is listening from client " + sc.getRemoteAddress() + " data rev is: " + content);
//將此對應的channel設定為準備下一次接受資料
sk.interestOps(SelectionKey.OP_READ);
}
catch (IOException io)
{
sk.cancel();
if(sk.channel() != null)
{
sk.channel().close();
}
}
if(content.length() > 0)
{
String[] arrayContent = content.toString().split(USER_CONTENT_SPILIT);
//註冊使用者
if(arrayContent != null && arrayContent.length ==1) {
String name = arrayContent[0];
if(users.contains(name)) {
sc.write(charset.encode(USER_EXIST));
} else {
users.add(name);
int num = OnlineNum(selector);
String message = "welcome "+name+" to chat room! Online numbers:"+num;
BroadCast(selector, null, message);
}
}
//註冊完了，傳送訊息
else if(arrayContent != null && arrayContent.length >1){
String name = arrayContent[0];
String message = content.substring(name.length()+USER_CONTENT_SPILIT.length());
message = name + " say " + message;
if(users.contains(name)) {
//不回發給傳送此內容的客戶端
BroadCast(selector, sc, message);
}
}
}
}
}
//TODO 要是能檢測下線，就不用這麼統計了
public static int OnlineNum(Selector selector) {
int res = 0;
for(SelectionKey key : selector.keys())
{
Channel targetchannel = key.channel();
if(targetchannel instanceof SocketChannel)
{
res++;
}
}
return res;
}
public void BroadCast(Selector selector, SocketChannel except, String content) throws IOException {
//廣播資料到所有的SocketChannel中
for(SelectionKey key : selector.keys())
{
Channel targetchannel = key.channel();
//如果except不為空，不回發給傳送此內容的客戶端
if(targetchannel instanceof SocketChannel && targetchannel!=except)
{
SocketChannel dest = (SocketChannel)targetchannel;
dest.write(charset.encode(content));
}
}
}
public static void main(String[] args) throws IOException
{
new ChatRoomServer().init();
}
}
client程式碼
package com.huahuiyang.channel;
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.nio.charset.Charset;
import java.util.Iterator;
import java.util.Scanner;
import java.util.Set;
public class ChatRoomClient {
private Selector selector = null;
static final int port = 9999;
private Charset charset = Charset.forName("UTF-8");
private SocketChannel sc = null;
private String name = "";
private static String USER_EXIST = "system message: user exist, please change a name";
private static String USER_CONTENT_SPILIT = "#@#";
public void init() throws IOException
{
selector = Selector.open();
//連線遠端主機的IP和埠
sc = SocketChannel.open(new InetSocketAddress("127.0.0.1",port));
sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ);
//開闢一個新執行緒來讀取從伺服器端的資料
new Thread(new ClientThread()).start();
//在主執行緒中 從鍵盤讀取資料輸入到伺服器端
Scanner scan = new Scanner(System.in);
while(scan.hasNextLine())
{
String line = scan.nextLine();
if("".equals(line)) continue; //不允許發空訊息
if("".equals(name)) {
name = line;
line = name+USER_CONTENT_SPILIT;
} else {
line = name+USER_CONTENT_SPILIT+line;
}
sc.write(charset.encode(line));//sc既能寫也能讀，這邊是寫
}
}
private class ClientThread implements Runnable
{
public void run()
{
try
{
while(true) {
int readyChannels = selector.select();
if(readyChannels == 0) continue;
Set selectedKeys = selector.selectedKeys(); //可以通過這個方法，知道可用通道的集合
Iterator keyIterator = selectedKeys.iterator();
while(keyIterator.hasNext()) {
SelectionKey sk = (SelectionKey) keyIterator.next();
keyIterator.remove();
dealWithSelectionKey(sk);
}
}
}
catch (IOException io)
{}
}
private void dealWithSelectionKey(SelectionKey sk) throws IOException {
if(sk.isReadable())
{
//使用 NIO 讀取 Channel中的資料，這個和全域性變數sc是一樣的，因為只註冊了一個SocketChannel
//sc既能寫也能讀，這邊是讀
SocketChannel sc = (SocketChannel)sk.channel();
ByteBuffer buff = ByteBuffer.allocate(1024);
String content = "";
while(sc.read(buff) > 0)
{
buff.flip();
content += charset.decode(buff);
}
//若系統傳送通知名字已經存在，則需要換個暱稱
if(USER_EXIST.equals(content)) {
name = "";
}
System.out.println(content);
sk.interestOps(SelectionKey.OP_READ);
}
}
}
public static void main(String[] args) throws IOException
{
new ChatRoomClient().init();
}
}
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