我想创建一个可以接受多个连接的服务器，然后将 2 个客户端绑定为一对，并在这 2 个客户端之间转发数据。但它是关于多对客户的。我已经有多线程服务器，可以为每个新连接的客户端创建一个新线程。对我来说问题是这些线程彼此不知道，我必须以某种方式将 2 个客户端连接到一个连接对。
现在我只是这样创建这些对连接：我等待第一个客户端，然后等待第二个客户端，然后为客户端 1 的输入打开一个线程，该输入被转发到客户端 2，反之亦然.这不适用于多个客户端。
我怎样才能做到体面？
【问题讨论】：
标签： java multithreading sockets
在我看来，客户需要
第一个连接的客户端必须保持暂停（在您服务器的某个全局表中），直到第二个客户端连接。 一旦一对客户端被识别为对话者，您将创建一对线程来将每个客户端发送的数据转发给另一个客户端。
更新：示例
ClientSocket.java
package matchmaker;
import java.io.Closeable;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
public class ClientSocket implements Closeable {
private final Socket socket;
private final InputStream in;
private final OutputStream out;
private final String ownId;
private final String peerId;
public ClientSocket(Socket socket) throws IOException {
this.socket = socket;
this.in = socket.getInputStream();
this.out = socket.getOutputStream();
DataInputStream din = new DataInputStream(in);
this.ownId = din.readUTF();
this.peerId = din.readUTF();
}
public ClientSocket(String server, int port, String ownId, String peerId)
throws IOException {
this.socket = new Socket(server, port);
this.socket.setTcpNoDelay(true);
this.in = socket.getInputStream();
this.out = socket.getOutputStream();
this.ownId = ownId;
this.peerId = peerId;
DataOutputStream dout = new DataOutputStream(out);
dout.writeUTF(ownId);
dout.writeUTF(peerId);
}
public String getOwnId() {
return ownId;
}
public String getPeerId() {
return peerId;
}
public InputStream getInputStream() {
return in;
}
public OutputStream getOutputStream() {
return out;
}
@Override
public void close() throws IOException {
socket.close();
}
}
Matchmaker.java：服务器
package matchmaker;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
public class Matchmaker extends Thread {
private static final Logger LOG
= Logger.getLogger(Matchmaker.class.getName());
private final int port;
private final Map<ClientPair,ClientSocket> waiting = new HashMap<>();
public static void main(String[] args) {
try {
int port = 1234;
int st = 0;
for (String arg: args) {
switch (st) {
case 0:
switch (arg) {
case "-p":
st = 1;
break;
default:
System.out.println("Unknown option: " + arg);
return;
}
break;
case 1:
port = Integer.parseInt(arg);
st = 0;
break;
}
}
Matchmaker server = new Matchmaker(port);
server.start();
server.join();
} catch (InterruptedException ex) {
LOG.log(Level.SEVERE, null, ex);
}
}
private Matchmaker(int port) {
this.port = port;
setDaemon(true);
}
@Override
public void run() {
try {
ServerSocket server = new ServerSocket(port);
while (true) {
ClientSocket socket = new ClientSocket(server.accept());
ClientPair pair = new ClientPair(
socket.getOwnId(), socket.getPeerId());
ClientSocket other;
synchronized(this) {
other = waiting.remove(pair.opposite());
if (other == null) {
waiting.put(pair, socket);
}
}
if (other != null) {
LOG.log(Level.INFO, "Establishing connection for {0}",
pair);
establishConnection(socket, other);
} else {
LOG.log(Level.INFO, "Waiting for counterpart {0}", pair);
}
}
} catch (IOException ex) {
LOG.log(Level.SEVERE, null, ex);
}
}
private void establishConnection(ClientSocket socket, ClientSocket other)
throws IOException {
Thread thread = new StreamCopier(
socket.getInputStream(), other.getOutputStream());
thread.start();
thread = new StreamCopier(
other.getInputStream(), socket.getOutputStream());
thread.start();
}
}
StreamCopier.java：从 InputStream 读取并写入 OutputStream 的线程
package matchmaker;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.logging.Level;
import java.util.logging.Logger;
public class StreamCopier extends Thread {
private static final Logger LOG
= Logger.getLogger(StreamCopier.class.getName());
private final InputStream in;
private final OutputStream out;
public StreamCopier(InputStream in, OutputStream out) {
this.in = in;
this.out = out;
setDaemon(true);
}
@Override
public void run() {
LOG.info("Start stream copier");
try {
for (int b = in.read(); b != -1; b = in.read()) {
out.write(b);
}
} catch (IOException ex) {
LOG.log(Level.SEVERE, null, ex);
} finally {
LOG.info("End stream copier");
try {
out.close();
} catch (IOException ex) {
LOG.log(Level.SEVERE, null, ex);
}
}
}
}
ClientPair.java：一对客户端 ID
package matchmaker;
public class ClientPair {
private final String client1;
private final String client2;
public ClientPair(String client1, String client2) {
this.client1 = client1;
this.client2 = client2;
}
public String getClient1() {
return client1;
}
public String getClient2() {
return client2;
}
public ClientPair opposite() {
return new ClientPair(client2, client1);
}
@Override
public int hashCode() {
int hash = 5;
hash = 73 * hash + client1.hashCode();
hash = 73 * hash + client2.hashCode();
return hash;
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final ClientPair other = (ClientPair) obj;
return client1.equals(other.client1) && client2.equals(other.client2);
}
@Override
public String toString() {
return "[" + client1 + "," + client2 + "]";
}
}
ReaderClient.java：一个从套接字读取并写入标准输出的示例客户端
package matchmaker;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.logging.Level;
import java.util.logging.Logger;
public class ReaderClient {
private static final Logger LOG = Logger.getLogger(ReaderClient.class.getName());
public static void main(String[] args) {
try (ClientSocket client
= new ClientSocket("localhost", 1234, "reader", "writer")) {
Reader reader
= new InputStreamReader(client.getInputStream(), "UTF-8");
BufferedReader in = new BufferedReader(reader);
for (String s = in.readLine(); s != null; s = in.readLine()) {
System.out.println(s);
}
} catch (IOException ex) {
LOG.log(Level.SEVERE, null, ex);
}
}
}
WriterClient.java：写入套接字的示例客户端
package matchmaker;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.logging.Level;
import java.util.logging.Logger;
public class WriterClient {
private static final Logger LOG = Logger.getLogger(ReaderClient.class.getName());
public static void main(String[] args) {
try (ClientSocket client
= new ClientSocket("localhost", 1234, "writer", "reader")) {
Writer writer
= new OutputStreamWriter(client.getOutputStream(), "UTF-8");
PrintWriter out = new PrintWriter(writer);
for (int i = 0; i < 30; ++i) {
out.println("Message line " + i);
}
out.flush();
} catch (IOException ex) {
LOG.log(Level.SEVERE, null, ex);
}
}
}
【讨论】：