我尝试做的是在服务器中创建接收器类，它从客户端接收已发送的消息并在客户端中创建发送者类。我试图先在服务器中设置接收器，因为我可能会在学习之后弄清楚如何在客户端做到这一点。但这样做会给我java.net.BindException: Address already in use: JVM_Bind。我认为这是因为我在接收器中有另一个Server server = new Server();。我该如何解决这个问题？
Server.java
package MultithreadingServerClient;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
public class Server {
ServerSocket serverSocket = new ServerSocket(3000);
Socket socket = serverSocket.accept();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter printWriter = new PrintWriter(socket.getOutputStream(), true);
public Server() throws IOException {
}
public static void main(String[] args) {
Thread serverSender = new Thread(new ServerSender());
Thread serverReceiver = new Thread(new ServerReceiver());
serverSender.start();
serverReceiver.start();
}
}
// Sender class
class ServerSender implements Runnable {
@Override
public void run() {
try {
Server serve = new Server();
Scanner scanner = new Scanner(System.in);
String msg = "";
while (!msg.equalsIgnoreCase("exit")) {
System.out.print("Server: ");
msg = scanner.nextLine();
serve.printWriter.println(msg);
}
} catch (IOException e) {
System.err.println("Sender Error " + e);
}
}
}
class ServerReceiver implements Runnable {
@Override
public void run() {
try {
Server server = new Server();
System.out.println(server.bufferedReader.readLine());
} catch (IOException e) {
System.err.println("Receiver Error " + e);
}
}
}
Client.java
package MultithreadingServerClient;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
public class Client {
Socket socket = new Socket("localhost", 3000);
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter printWriter = new PrintWriter(socket.getOutputStream());
public Client() throws IOException {
}
// Receive messages
public static void main(String[] args) {
try {
Client client = new Client();
while (true) {
System.out.println("Server: " + client.bufferedReader.readLine());
}
} catch (IOException e) {
System.out.println("Server Closed!");
}
}
}
class ClientSender implements Runnable {
@Override
public void run() {
try {
Client client = new Client();
client.printWriter.println("Test message: send to Server");
} catch (IOException e) {
e.printStackTrace();
}
}
}
答案 0 :(得分：2)
不要创建Server的多个实例，您可以在main中创建实例，然后将bufferedReader传递给接收者类，将printWriter传递给发件人类。
发件人类：
class ServerSender implements Runnable {
private PrintWriter writer;
public ServerSender(PrintWriter printWriter){
writer = printWriter;
}
@Override
public void run() {
try {
Scanner scanner = new Scanner(System.in);
String msg = "";
while (!msg.equalsIgnoreCase("exit")) {
System.out.print("Server: ");
msg = scanner.nextLine();
writer.println(msg);
}
} catch (IOException e) {
System.err.println("Sender Error " + e);
}
}
}
接收者类：
class ServerReceiver implements Runnable {
private BufferedReader reader;
public ServerReceiver(BufferedReader bufferedReader){
reader = bufferedReader;
}
@Override
public void run() {
try {
System.out.println(reader.readLine());
} catch (IOException e) {
System.err.println("Receiver Error " + e);
}
}
}
main中的方法Server：
public static void main(String[] args) {
Server serve = new Server();
Thread serverSender = new Thread(new ServerSender(serve.printWriter));
Thread serverReceiver = new Thread(new ServerReceiver(serve.bufferedReader));
serverSender.start();
serverReceiver.start();
}
答案 1 :(得分：0)
您有两个线程在同一端口（3000）启动新连接实例。我假设您尝试让一个线程从服务器接收消息，另一个线程用于向客户端发送消息。我不认为你需要这样的设计。这可以在单线程环境中完成。客户端（发送者和接收者）和服务器（发送者和接收者）不需要。
的ServerSocket.accept（）;方法将侦听传入指定端口号的所有消息。
为了让服务器向客户端发送回复。您可以使用 DataOutputStream.writeUTF（）＆amp; DataOutputStream.flush（）方法。
客户端也是如此。看看下面的程序。
class Server {
public static void main(String args[]) throws IOException {
try (ServerSocket serverSocket = new ServerSocket(3333); // open connection at port 3333
Socket socket = serverSocket.accept();
DataInputStream inputStream = new DataInputStream(socket.getInputStream());) {
DataOutputStream outStream = new DataOutputStream(socket.getOutputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String messageFromClient = "", messageToBeClient = "";
while (!messageFromClient.equals("exit")) {
messageFromClient = inputStream.readUTF();
System.out.println("Message From Client : " + messageFromClient);
messageToBeClient = reader.readLine();
outStream.writeUTF(messageToBeClient);
outStream.flush();
}
}
}
}
class Client {
public static void main(String args[]) throws Exception {
try (Socket socket = new Socket("localhost", 3333); // establish connection to the open socket at port 3333
DataInputStream inputStream = new DataInputStream(socket.getInputStream());) {
DataOutputStream outStream = new DataOutputStream(socket.getOutputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String messageFromServer = "", messageToServer = "";
while (!messageToServer.equals("exit")) {
messageToServer = reader.readLine();
outStream.writeUTF(messageToServer);
outStream.flush();
messageFromServer = inputStream.readUTF();
System.out.println("Message From Server : " + messageFromServer);
}
}
}
}