我正在编写一个统计插件,在加入时,从数据库中检索统计数据,将它们实现为哈希映射,并在退出时将这些新统计数据实现到数据库中,这样做的原因是没有像每秒打开连接那样多的延迟。
如果这意味着什么,我使用MariaDB。
hashmap下面
public static HashMap<String, Integer> kills = new HashMap<String, Integer>();
public static HashMap<String, Integer> deaths = new HashMap<String, Integer>();
下面的代码
@EventHandler
public void onDeath(PlayerDeathEvent event){
Player p = event.getEntity();
Player k = p.getKiller();
kills.put(k.getName(), kills.get(k.getName() + 1));
deaths.put(p.getName(), deaths.get(p.getName() + 1));
removeScoreboard(p);
setScoreboard(p);
removeScoreboard(k);
setScoreboard(k);
}
@EventHandler
public void onJoin(PlayerJoinEvent e){
OfflinePlayer p2 = e.getPlayer();
Player p = e.getPlayer();
openConnection();
try{
int previousDeaths = 0;
int previousKills = 0;
if(playerDataContainsPlayer(p)){
PreparedStatement sql = connection.prepareStatement("SELECT deaths FROM `player_data` WHERE player=?;");
PreparedStatement sql2 = connection.prepareStatement("SELECT kills FROM `player_data` WHERE player=?;");
ResultSet result = sql.executeQuery();
ResultSet result2 = sql2.executeQuery();
result2.next();
result.next();
previousDeaths = result.getInt("deaths");
previousKills = result2.getInt("kills");
kills.put(p.getName(), previousKills);
deaths.put(p.getName(), previousDeaths);
sql.close();
sql2.close();
result.close();
result2.close();
removeScoreboard(p);
setScoreboard(p);
} else {
PreparedStatement newPlayer = connection.prepareStatement("INSERT INTO `player_data` values(?,0,0);");
newPlayer.setString(1, p.getUniqueId().toString());
newPlayer.setInt(2, 0);
newPlayer.setInt(3, 0);
newPlayer.execute();
newPlayer.close();
kills.put(p.getName(), 0);
deaths.put(p.getName(), 0);
removeScoreboard(p);
setScoreboard(p);
}
}catch(Exception e1){
e1.printStackTrace();
} finally{
closeConnection();
}
}
@EventHandler
public void onLeave(PlayerQuitEvent e){
Player p = e.getPlayer();
openConnection();
try{
int previousDeaths = 0;
int previousKills = 0;
if(playerDataContainsPlayer(p)){
PreparedStatement sql = connection.prepareStatement("SELECT deaths FROM `player_data` WHERE player=?;");
PreparedStatement sql2 = connection.prepareStatement("SELECT kills FROM `player_data` WHERE player=?;");
sql.setString(1, p.getUniqueId().toString());
sql2.setString(1, p.getUniqueId().toString());
ResultSet result = sql.executeQuery();
ResultSet result2 = sql2.executeQuery();
result2.next();
result.next();
previousDeaths = result.getInt("deaths");
previousKills = result2.getInt("kills");
PreparedStatement killsUpdate = connection.prepareStatement("UPDATE `player_data` SET kills=? WHERE player=?;");
killsUpdate.setInt(1, kills.get(p.getName()));
killsUpdate.setString(2, p.getUniqueId().toString());
killsUpdate.executeUpdate();
PreparedStatement deathsUpdate = connection.prepareStatement("UPDATE `player_data` SET deaths=? WHERE player=?;");
deathsUpdate.setInt(1, deaths.get(p.getName()));
deathsUpdate.setString(2, p.getUniqueId().toString());
deathsUpdate.executeUpdate();
deathsUpdate.close();
killsUpdate.close();
sql.close();
sql2.close();
result.close();
result2.close();
}
}catch(Exception e1){
e1.printStackTrace();
} finally{
closeConnection();
}
}
当你加入时,它说[20:51:43 WARN]: java.sql.SQLException: No value specified for parameter 1
当你杀死某人或死亡时,你的杀戮为零,你的死亡也为零。我不确定为什么会发生这种情况,任何帮助都很感激。
这里没有为PreparedStatement设置参数。
PreparedStatement sql = connection.prepareStatement("SELECT deaths FROM `player_data` WHERE player=?");
PreparedStatement sql2 = connection.prepareStatement("SELECT kills FROM `player_data` WHERE player=?");
根据where条件的数据类型设置参数。preparedStatement。setInt (1001),
参考:https://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html
第二个问题:
请按如下方式设置hashmap值
previousDeaths = result.getInt("deaths");
previousKills = result2.getInt("kills");
kills.put(p.getName(), previousKills);
deaths.put(p.getName(), previousDeaths);
PreparedStatement killsUpdate = connection.prepareStatement("UPDATE `player_data` SET kills=? WHERE player=?;");
killsUpdate.setInt(1, kills.get(p.getName()));
killsUpdate.setString(2, p.getUniqueId().toString());
killsUpdate.executeUpdate();