上期我们完成了游戏大厅的前端部分内容，今天我们实现后端部分内容 

1. 维护在线用户

在用户登录成功后，我们可以维护好用户的websocket会话，把用户表示为在线状态，方便获取到用户的websocket会话

package org.ting.j20250110_gobang.game;import org.springframework.stereotype.Component;
import org.springframework.web.socket.WebSocketSession;import java.util.HashMap;
import java.util.Map;@Component
public class OnlineUserManager {//使用ConcurrentHashMap保证线程安全private Map<Integer, WebSocketSession> onlineUser = new ConcurrentHashMap<>();public void enterGameHall(int userId, WebSocketSession session) {//用户上线onlineUser.put(userId, session);}public void exitGameHall(int userId) {//用户下线onlineUser.remove(userId);}public WebSocketSession getFromHall(int userId) {//获取用户的websocket会话return onlineUser.get(userId);}
}

这里我们借助一个哈希表就可以实现。

2. 实现webSocket相关方法

上期我们定义了webSocket的处理类，但是并没有完成重写的方法，接下来我们借助维护的在线用户具体实现如下方法

在实现这些方法之前，我们还需要按照上期约定好的信息交互形式定义两个实体类，代表请求和响应：

package org.ting.j20250110_gobang.game;public class MatchRequest {private String message;public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}
}

package org.ting.j20250110_gobang.game;public class MatchResponse {private boolean ok;private String errMsg;private String message;public boolean isOk() {return ok;}public void setOk(boolean ok) {this.ok = ok;}public String getErrMsg() {return errMsg;}public void setErrMsg(String errMsg) {this.errMsg = errMsg;}public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}
}

2.1 连接成功

//连接成功后执行@Overridepublic void afterConnectionEstablished(WebSocketSession session) throws Exception {//玩家上线try {//获取登录时储存在session中的用户信息，这里WebSocketSession在注册时通过拦截器获取到了session中的内容User user = (User)session.getAttributes().get("user");if(onlineUser.getFromHall(user.getId()) == null) {onlineUser.enterGameHall(user.getId(), session);System.out.println("用户：" + user.getUsername() + " 已上线");}else{//防止重复登录MatchResponse response = new MatchResponse();response.setOk(false);response.setErrMsg("用户已在别处登录");session.sendMessage(new TextMessage(objectMapper.writeValueAsString(response)));session.close();}}catch (NullPointerException e) {e.printStackTrace();MatchResponse response = new MatchResponse();response.setOk(false);response.setErrMsg("用户未登录");session.sendMessage(new TextMessage(objectMapper.writeValueAsString(response)));}}

2.2 连接断开

    //连接异常时执行@Overridepublic void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {//连接异常断开，玩家下线try {User user = (User)session.getAttributes().get("user");//防止重复登录时删除正常登录的在线信息if(onlineUser.getFromHall(user.getId()).equals(session)) {onlineUser.exitGameHall(user.getId());System.out.println("用户：" + user.getUsername() + " 已下线");}}catch (NullPointerException e) {e.printStackTrace();MatchResponse response = new MatchResponse();response.setOk(false);response.setErrMsg("用户未登录");session.sendMessage(new TextMessage(objectMapper.writeValueAsString(response)));}}//连接正常断开后执行@Overridepublic void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {//连接正常断开，玩家下线try {User user = (User)session.getAttributes().get("user");//防止重复登录时删除正常登录的在线信息if(onlineUser.getFromHall(user.getId()).equals(session)) {onlineUser.exitGameHall(user.getId());System.out.println("用户：" + user.getUsername() + " 已下线");}}catch (NullPointerException e) {e.printStackTrace();MatchResponse response = new MatchResponse();response.setOk(false);response.setErrMsg("用户未登录");session.sendMessage(new TextMessage(objectMapper.writeValueAsString(response)));}}

2.3 处理匹配请求

    //接收到请求后执行@Overrideprotected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {User user = (User) session.getAttributes().get("user");MatchRequest request = objectMapper.readValue(message.getPayload(), MatchRequest.class);MatchResponse response = new MatchResponse();if(request.getMessage().equals("startMatch")) {//开始匹配，把用户加入匹配队列//todoresponse.setOk(true);response.setMessage("startMatch");}else if(request.getMessage().equals("stopMatch")) {//取消匹配，从匹配队列中移除用户//todoresponse.setOk(true);response.setMessage("stopMatch");}else{response.setOk(false);response.setErrMsg("非法请求");}}

这里=具体的匹配队列功能我们下期再实现