java整理知识点

Set<WebSocket> keySet = map.keySet();

/**
* 获取WebSocket
* @param user
*/
public static WebSocket getWebSocketByUser(String user){
Set<WebSocket> keySet = userconnections.keySet();
synchronized (keySet) { //对象加锁，锁住的是这个对象，而不是代码。
for (WebSocket conn : keySet) {
String cuser = userconnections.get(conn);
if(cuser.equals(user)){
return conn;
}
}
}
return null;
}