长期以来，我一直在“搜索”服务器-客户端-聊天应用程序的示例，但我无法真正理解它们。他们中的许多人正在使用一个类并从中创建 GUI，我不想直接从中复制。许多示例并没有真正解释您如何将消息从客户端发送到服务器，然后将消息发送到所有其他客户端。
我正在使用 NetBeans，我想知道是否有一些好的教程或示例可以帮助我解决这个问题？
【问题讨论】：
main。此外，这不是寻求教程或示例的网站，而是特定编程问题的网站。
标签： java netbeans client chat server
这是我刚刚制作的一个超级简单的内容，其中包含一些正在发生的事情。连接到服务器的客户端可以键入服务器将打印出的消息。这不是聊天程序，因为服务器接收消息，客户端发送消息。但希望你能更好地理解它:)
服务器：
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
public class Main {
public static DataInputStream in;
public static DataOutputStream out;
public static void main(String[] args) throws IOException {
int port = 4444;
ServerSocket server = null;
Socket clientSocket = null;
try {
//start listening on port
server = new ServerSocket(port);
System.out.println("Listening on port: " + port);
//Accept client
clientSocket = server.accept();
System.out.println("client Connected!");
//initialize streams so we can send message
in = new DataInputStream(clientSocket.getInputStream());
out = new DataOutputStream(clientSocket.getOutputStream());
String message = null;
while (true) {
// as soon as a message is being received, print it out!
message = in.readUTF();
System.out.println(message);
}
}
catch (IOException e){
e.printStackTrace();
if (!server.isClosed()){server.close();}
if (!clientSocket.isClosed()){clientSocket.close();}
}
}
}
客户：
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;
public class Main
{
public static void main(String[] args) throws IOException {
//declare a scanner so we can write a message
Scanner keyboard = new Scanner(System.in);
// localhost ip
String ip = "127.0.0.1";
int port = 4444;
Socket socket = null;
try {
//connect
socket = new Socket(ip, port);
//initialize streams
DataInputStream in = new DataInputStream(socket.getInputStream());
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
while (true){
System.out.print("\nMessage to server: ");
//Write a message :)
String message = keyboard.nextLine();
//Send it to the server which will just print it out
out.writeUTF(message);
}
}
catch (IOException e){
e.printStackTrace();
if (!socket.isClosed()){socket.close();}
}
}
}
【讨论】：
多线程程序来了：）服务器有两个类，客户端有一个。希望你喜欢！
服务器主类：
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
public class Main {
public static void main(String[] args) throws IOException {
int MAXCLIENTS = 20;
int port = 4444;
ServerSocket server = null;
Socket clientSocket = null;
// An array of clientsConnected instances
ClientThread[] clientsConnected = new ClientThread[MAXCLIENTS];
try {
server = new ServerSocket(port);
System.out.println("listening on port: " + port);
} catch (IOException e) {// TODO Auto-generated catch block
e.printStackTrace();
}
while (true) {
try {
clientSocket = server.accept();
} catch (IOException e) {
e.printStackTrace();
if (!server.isClosed()){server.close();}
if (!clientSocket.isClosed()){clientSocket.close();}
}
System.out.println("Client connected!");
for (int c = 0; c < clientsConnected.length; c++){
if (clientsConnected[c] == null){
// if it is empty ( null) then start a new Thread, and pass the socket and the object of itself as parameter
(clientsConnected[c] = new ClientThread(clientSocket, clientsConnected)).start();
break; // have to break, else it will start 20 threads when the first client connects :P
}
}
}
}
}
服务器客户端类：
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
public class ClientThread extends Thread{
private ClientThread[] clientsConnected;
private Socket socket = null;
private DataInputStream in = null;
private DataOutputStream out = null;
private String clientName = null;
//Constructor
public ClientThread(Socket socket, ClientThread[] clientsConnected){
this.socket = socket;
this.clientsConnected = clientsConnected;
}
public void run(){
try {
// Streams :)
in = new DataInputStream(socket.getInputStream());
out = new DataOutputStream(socket.getOutputStream());
String message = null;
clientName = in.readUTF();
while (true){
message = in.readUTF();
for (int c = 0; c < clientsConnected.length; c++){
if (clientsConnected[c]!= null && clientsConnected[c].clientName != this.clientName){ //dont send message to your self ;)
clientsConnected[c].sendMessage(message, clientName); // loops through all the list and calls the objects sendMessage method.
}
}
}
} catch (IOException e) {
System.out.println("Client disconnected!");
this.clientsConnected = null;
}
}
// Every instance of this class ( the client ) will have this method.
private void sendMessage(String mess, String name){
try {
out.writeUTF(name + " says: " + mess);
} catch (IOException e) {
e.printStackTrace();
}
}
}
最后是客户：
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;
public class Main
{
public static void main(String[] args) throws IOException {
Main m = new Main();
m.connect();
}
public void connect() throws IOException{
//declare a scanner so we can write a message
Scanner keyboard = new Scanner(System.in);
// localhost ip
String ip = "127.0.0.1";
int port = 4444;
Socket socket = null;
System.out.print("Enter your name: ");
String name = keyboard.nextLine();
try {
//connect
socket = new Socket(ip, port);
//initialize streams
DataInputStream in = new DataInputStream(socket.getInputStream());
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
//start a thread which will start listening for messages
new ReceiveMessage(in).start();
// send the name to the server!
out.writeUTF(name);
while (true){
//Write messages :)
String message = keyboard.nextLine();
out.writeUTF(message);
}
}
catch (IOException e){
e.printStackTrace();
if (!socket.isClosed()){socket.close();}
}
}
class ReceiveMessage extends Thread{
DataInputStream in;
ReceiveMessage(DataInputStream in){
this.in = in;
}
public void run(){
String message;
while (true){
try {
message = in.readUTF();
System.out.println(message);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
我在eclipse中运行服务器，并从CMD启动了两个客户端，如下所示：
【讨论】：