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：