[英]Can I host Chat Server on Dynamic IP using Java Socket?
調查Servlets我創建了一個簡單的聊天並在本地IP上測試它 - 一切正常。 但是當我試圖通過真實網絡測試它時連接被拒絕了 - java.net.ConnectException: Connection refused: connect
。 我有動態IP的原因,還是需要其他設置? 提前致謝!
服務器:
/**
* Created by rnd on 7/4/2017.
*/
import java.io.*;
import java.net.*;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.*;
public class VerySimpleChatServer {
ArrayList clientOutputStreams;
public static void main (String[] args) {
new VerySimpleChatServer().go();
}
public void go() {
clientOutputStreams = new ArrayList();
try {
ServerSocket serverSock = new ServerSocket(5000);
while(true) {
Socket clientSocket = serverSock.accept();
Charset charset = StandardCharsets.UTF_8;
OutputStreamWriter osw = new OutputStreamWriter( clientSocket.getOutputStream(), charset );
PrintWriter writer = new PrintWriter( new BufferedWriter( osw ) );
// PrintWriter writer = new PrintWriter(clientSocket.getOutputStream());
writer.println("Welcome to the chat 7 kids.... Семеро Козлят");
writer.flush();
clientOutputStreams.add(writer);
Thread t = new Thread(new ClientHandler(clientSocket));
t.start() ;
System.out.println("got a connection");
}
} catch(Exception ex) {
ex.printStackTrace();
}
} // Закрываем go
public class ClientHandler implements Runnable {
BufferedReader reader;
Socket sock;
public ClientHandler(Socket clientSocket) {
try {
sock = clientSocket;
InputStreamReader isReader = new InputStreamReader(sock.getInputStream(), StandardCharsets.UTF_8);
reader = new BufferedReader(isReader);
} catch(Exception ex) {ex.printStackTrace();}
} // Закрываем конструктор
public void run() {
String message;
try {
while ((message = reader.readLine()) != null) {
System.out.println("read " + message);
tellEveryone(message);
} // Закрываем while
} catch(Exception ex) {ex.printStackTrace();}
} // Закрываем run
} // Закрываем вложенный класс
public void tellEveryone(String message) {
Iterator it = clientOutputStreams.iterator();
while(it.hasNext()) {
try {
PrintWriter writer = (PrintWriter) it.next();
writer.println(message);
writer.flush();
} catch(Exception ex) {
ex.printStackTrace();
}
} // Конец цикла while
} // Закрываем tellEveryone
} // Закрываем класс
客戶:
/**
* Created by rnd on 7/4/2017.
*/
import java.io.*;
import java.net.*;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class SimpleChatClient {
JTextArea incoming;
JTextField outgoing;
BufferedReader reader;
PrintWriter writer;
Socket sock;
public static void main(String[] args) {
SimpleChatClient client = new SimpleChatClient();
client.go();}
public void go(){
JFrame frame = new JFrame("Ludicrously Simple Chat Client");
JPanel mainPanel = new JPanel();
incoming = new JTextArea(15,50);
incoming.setLineWrap(true);
incoming. setWrapStyleWord (true) ;
incoming.setEditable(false);
JScrollPane qScroller = new JScrollPane(incoming);
qScroller. setVerticalScrollBarPolicy (ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS) ;
qScroller. setHorizontalScrollBarPolicy (ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS) ;
outgoing = new JTextField(20);
JButton sendButton = new JButton("Send") ;
sendButton.addActionListener(new SendButtonListener());
mainPanel.add(qScroller);
mainPanel.add(outgoing);
mainPanel.add(sendButton);
setUpNetworking();
Thread readerThread = new Thread(new IncomingReader());
readerThread.start();
frame.getContentPane().add(BorderLayout.CENTER, mainPanel);
frame.setSize(800,500);
frame.setVisible(true);
}
private void setUpNetworking() {
try {
sock = new Socket("178.165.87.221", 5000);
InputStreamReader streamReader = new InputStreamReader(sock.getInputStream(), StandardCharsets.UTF_8 );
reader = new BufferedReader(streamReader);
Charset charset = StandardCharsets.UTF_8;
OutputStreamWriter osw = new OutputStreamWriter( sock.getOutputStream(), charset );
writer = new PrintWriter( new BufferedWriter( osw ) );
// writer = new PrintWriter(sock.getOutputStream());
System.out.println("networking established");
} catch (IOException ex) {
ex.printStackTrace();}
}
public class SendButtonListener implements ActionListener {
public void actionPerformed (ActionEvent ev) {
try {
writer.println(outgoing.getText());
writer.flush();
} catch(Exception ex) {
ex.printStackTrace();
}
outgoing. setText ("") ;
outgoing.requestFocus () ;}
}
public class IncomingReader implements Runnable{
@Override
public void run() {
String message;
try{
while((message=reader.readLine())!=null ){
System.out.println("read " + message);
incoming.append(message + "\n");
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
如果你真的有一個動態IP,你可以給自己一個freedns域(並添加一個防火牆例外),但很可能你是NAT背后的。 為了使它工作,你需要多個東西:
如圖所示,大多數NAT都是端口限制的錐形NAT,也就是說,它們會丟棄來自對等體的傳入UDP數據包,直到您向該對等體發送數據包為止。 此外,通過發送數據包創建的NAT UDP映射在大約60秒內到期,這比TCP映射要少得多。
所有這些都使得純粹的p2p消息傳遞無法用於NAT背后的各方。 要加入p2p網絡,您仍然需要通過公共服務器(電子郵件或其他即時消息提供程序)交換一些數據包。 有“ice4j”庫可以生成並解析這些數據包(SDP),然后為直接連接創建java套接字包裝器。
即使兩個對等端保存彼此的地址以便將來直接連接,地址最終也會因動態IP(通常為24小時)而到期。
聽起來好像防火牆拒絕連接或者路由器不是端口轉發,所以請求被拒絕。 這聽起來與擁有動態IP無關。
如果您位於路由器后面,則路由器中存在允許端口轉發的設置,您可能需要向防火牆添加規則。 無論如何,您可以通過嘗試從其他地方ping
服務器IP地址進行測試,如果響應,那么甚至嘗試使用telnet <server ip> port
來查看是否可以連接。
有些事情正在阻礙並拒絕連接!
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