java.sql.SQLException : Connection is closed [POOL-HikariCP]

您好我有一个连接问题，它正在执行查询时关闭连接。我不知道会发生什么D:
这是配置:

private static HikariDataSource Hikari;
public static String ID_Usuario;

public void connectToDatabase() {

    Hikari = new HikariDataSource();
    Hikari.setDriverClassName("com.mysql.jdbc.Driver");
    Hikari.setJdbcUrl("jdbc:mysql://localhost:3306/bank");
    Hikari.setUsername("root");
    Hikari.setPassword("");
    Hikari.setMaximumPoolSize(5);
    Hikari.setConnectionTimeout(300000);
    Hikari.addDataSourceProperty("cachePrepStmts", "true");
    Hikari.addDataSourceProperty("prepStmtCacheSize", "250");
    Hikari.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
    Hikari.setConnectionTestQuery("SELECT 1");
}

public HikariDataSource getHikari(){
    return Hikari;
}

现在，这是我使用池的类，首先，我从Hikari.getConnection()接收了一个连接。然后我将其保存在“连接”中

Pool HikariPool;
HikariDataSource Hikari;
Connection connection;

  public SQL() {
    initComponents();
  }

    public void initComponents(){
        HikariPool= new Pool();
        HikariPool.connectToDatabase();

    Hikari=HikariPool.getHikari();

    try{
       connection= Hikari.getConnection();
    }catch(SQLException e){
        e.printStackTrace();
    }
}

我在validateLogin()中使用“连接”

public int validateLogin(String nip){
   int validation=0;
   String SQL="SELECT * FROM bank.account WHERE No_Account='"+account+"'
    AND NIP='"+nip+"'";
    try{
        Statement stm=Conexion.createStatement();
        ResultSet rs= stm.executeQuery(SQL);
...

在“语句stm = connection.createStatement();”行中发生错误

它说 :

[AWT-EventQueue-0] INFO com.zaxxer.hikari.HikariDataSource - HikariPool-0
- is starting.
java.sql.SQLException: Connection is closed at
com.zaxxer.hikari.pool.ProxyConnection$ClosedConnection$1.invoke
(ProxyConnection.java:468)
at com.sun.proxy.$Proxy0.createStatement(Unknown Source)...

为什么要关闭连接？

最佳答案

您的代码结构对我来说还不太清楚。但是我不认为您想在initComponents()中分配一个Connection。当您需要运行查询时，应该获得一个Connection，然后将其关闭以将其返回到池中。

就像是...

public int validateLogin(String nip) {
   int validation=0;
   String SQL="SELECT * FROM bank.account WHERE No_Account='"+account+"'
    AND NIP='"+nip+"'";
    try (Connection conn = SQL.getConnection();
         Statement stm = conn.createStatement()) {
       ResultSet rs = stm.executeQuery(SQL);
       ...
    }
    catch (SQLException e) {
       ...
    }

“尝试使用资源”将自动关闭连接和语句。

而SQL.getConnection()的作用类似于:

public Connection getConnection() throws SQLException {
   return Hikari.getConnection();
}