Java网络编程之TCP

TCP主要需要两个类：Socket和ServerSocket，Socket是客户端连接服务器时创建，参数需要指定服务器的ip和端口，ServerSocket是服务器端创建，参数指定端口，如下：

Socket socket = new Socket("localhost",8888);//Client.java客户端

ServerSocket serverSocket = new ServerSocket(8888);//Server.java服务器端

//服务器ip为本机，端口为8888

我的想法：要实现单聊和群聊，首先，我得为标识每个客户端，我选择姓名，这样每个用户都知道是谁发的消息，那么，我需要每个姓名对应一个客户端Socket，用map存储

废话不多说，直接上代码：

1. 客户端：

  ```java

  public class TcpClient {

  	public static void main(String[] args) throws Exception {

  		Scanner scanner = new Scanner(System.in);

  		System.out.print("请输入用户名》》");

  		String userName = scanner.next();

  		Socket socket = new Socket("localhost",8888);

  		DataOutputStream out = new DataOutputStream(socket.getOutputStream());

  		out.writeUTF(userName);

  		new Thread(new SendMsg(socket)).start();

  		new Thread(new ReceiveMsg(socket)).start();

  	}

  }

  ```

2. 客户端发送消息线程：

public class SendMsg implements Runnable{

	private Socket socket;

	public SendMsg(Socket socket) {

		this.socket = socket;

	}

	@Override

	public void run() {

		try {

			while(true) {

				BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in));

				String[] msg = buffer.readLine().split("@");

				MessageBean messageBean = new MessageBean(msg[0],msg[1]);

//				DataOutputStream out = new DataOutputStream(socket.getOutputStream());

//				out.writeUTF(msg);

				ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());

				out.writeObject(messageBean);

			}

		} catch (Exception e) {

			e.printStackTrace();

		}

	}

}

3. 客户端接收消息线程：

public class ReceiveMsg implements Runnable{

	private Socket socket;

	public ReceiveMsg(Socket socket) {

		this.socket = socket;

	}

	@Override

	public void run() {

		try {

			while(true) {

				DataInputStream in = new DataInputStream(socket.getInputStream());

				System.out.println(in.readUTF());

			}

		} catch (Exception e) {

			e.printStackTrace();

		}

	}

}

4. 服务器端：

public class TcpServer {

	public static void main(String[] args) throws Exception {

		try {

			//List<Socket> sockets = new ArrayList<>();

			Map<String,Socket> map = new HashMap<>();

			ServerSocket serverSocket = new ServerSocket(8888);

			while(true) {

				Socket socket = serverSocket.accept();

				//服务器第一次接收到的信息一定是用户名

				DataInputStream in = new DataInputStream(socket.getInputStream());

				String username = in.readUTF();

				synchronized (map) {

					map.put(username, socket);

				}

				//能够保证在同一时刻最多只有一个线程执行该段代码，以达到保证并发安全的效果

//				synchronized (sockets) {

//					sockets.add(socket);

//				}

				new Thread(new ServerHandler(socket,map)).start();

			}

		} catch (Exception e) {

			e.printStackTrace();

		}

	}

}

5. 服务器处理事务线程端：

public class ServerHandler implements Runnable {

	private Socket socket;

	private Map<String, Socket> map;

	public ServerHandler(Socket socket,Map<String, Socket> map) {

		this.socket = socket;

		this.map = map;

	}

	public String findKey(Map<String, Socket> map,Socket socket) {

		Iterator<String> it = map.keySet().iterator();

		while (it.hasNext()) {

			String key = it.next();

			if (map.get(key).equals(socket)) return key;

		 }

		return null;

	}

	@Override

	public void run() {

		InetAddress address = socket.getInetAddress();

		String ip = address.getHostAddress();

		String username = findKey(map, socket);

	    System.out.println("ip为"+ip+"的"+username+":上线了----");

		try {

			while(true) {

				ObjectInputStream in = new ObjectInputStream(socket.getInputStream());

				MessageBean messageBean = (MessageBean) in.readObject();

				String msg = messageBean.getMsg();

				String toPerson = messageBean.getToPerson();

				if ("all".equals(toPerson)) {

					//群聊

					msg = username+":"+msg;

					for(String key : map.keySet()){

					    if (username.equals(key)) {

							continue;

						}

					    DataOutputStream out = new DataOutputStream(map.get(key).getOutputStream());

					    out.writeUTF(msg);

					}

				}else {

					//私聊

					if (map.get(toPerson) == null) {

						DataOutputStream out = new DataOutputStream(map.get(username).getOutputStream());

					    out.writeUTF("抱歉，"+toPerson+"不在线。。。。");

					}else {

						msg = username+"对您私聊说:"+msg;

						DataOutputStream out = new DataOutputStream(map.get(toPerson).getOutputStream());

					    out.writeUTF(msg);

					}

				}

			}

		} catch (Exception e) {

			//e.printStackTrace();

			System.out.println(username+"下线了。。。。。");

			synchronized (map) {

				map.remove(username, socket);

			}

		}

	}

}

6. 消息体类：

public class MessageBean implements Serializable{

	private String msg;

	private String toPerson;

	public MessageBean() {

	}

	public MessageBean(String msg,String toPerson) {

		this.msg = msg;

		this.toPerson = toPerson;

	}

	public String getMsg() {

		return msg;

	}

	public String getToPerson() {

		return toPerson;

	}

	public void setMsg(String msg) {

		this.msg = msg;

	}

	public void setToPerson(String toPerson) {

		this.toPerson = toPerson;

	}

}

运行结果：

巴特西

Java网络编程之TCP

Java网络编程之TCP

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