个人博客

2021年5月19日：

今天想了一个办法来解决别人断线的问题，以下是加的几串代码：

private static Map<String, List<String>> map = new HashMap<>();
private static List<String> list = new ArrayList<>();

我给websocket类加了两个属性，分别是一个map集合和一个list集合，这个map集合的作用在于当用户上线时，就会往map集合中添加一个用户，当用户下线时，如果检测不到该用户就会把相应的信息存到list集合中，然后只要用户一上线那就把list集合中的信息循环的发给他，这样一来就完美的解决了用户下线的问题。

以下是我的websocket的完整代码：

package com.atguigu.crud.utils;

import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import org.springframework.stereotype.Component;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

@ServerEndpoint("/websocket/{userno}")
@Component
public class websocket {
private static ConcurrentHashMap<String, websocket> webSocketSet = new ConcurrentHashMap<String, websocket>();
private static Map<String, List<String>> map = new HashMap<>();
private static List<String> list = new ArrayList<>();
private Session WebSocketsession;
private String userno = "";

@OnOpen
public void onOpen(@PathParam(value = "userno") String param, Session WebSocketsession, EndpointConfig config)
throws IOException {
userno = param;
this.WebSocketsession = WebSocketsession;
websocket webSocketServer = webSocketSet.get(param);
if (webSocketServer != null) { // 同样业务的连接已经在线，则把原来的挤下线。
webSocketServer.WebSocketsession.getBasicRemote().sendText(param + "重复连接被挤下线了");
webSocketServer.WebSocketsession.close();
}
webSocketSet.put(param, this);
if (map.get(param) != null) {
webSocketSet.get(param).sendMessage(param);
}
}

@OnClose
public void onClose() {
if (!userno.equals("")) {
webSocketSet.remove(userno);
}
}

@OnMessage
public void onMessage(String message) {
if (message.split("[|]")[1].contains(",")) {
sendAll(message.split("[|]")[1].split(","));
} else {
sendToUser(message);
}
}
public void sendToUser(String message) {
String sendUserno = message.split("[|]")[1];
String sendMessage = message.split("[|]")[0];
try {
if (webSocketSet.get(sendUserno) != null) {
webSocketSet.get(sendUserno).sendMessage(sendUserno);
} else {
if (map.get(sendUserno) == null) {
map.put(sendUserno, list);
map.get(sendUserno).add(sendMessage);
} else {
map.get(sendUserno).add(sendMessage);
}
}
} catch (IOException e) {
}
}

private void sendAll(String a[]) {
for (String key : a) {
try {
if (webSocketSet.get(key) != null) {
webSocketSet.get(key).sendMessage(key);
} else {
if (map.get(key) == null) {
map.put(key, list);
map.get(key).add(key);
} else {
map.get(key).add(key);
}
}
} catch (IOException e) {
}
}
}

@OnError
public void onError(Session session, Throwable error) {
error.printStackTrace();
}

public void sendMessage(String message) throws IOException {
this.WebSocketsession.getBasicRemote().sendText(message);
}
}