java.sql.SQLException：ResultSet关闭MySQL Java后不允许操作

每当我尝试使用这种方法时，我都会继续这样做。

java.sql.SQLException: Operation not allowed after ResultSet closed at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926) at com.mysql.jdbc.ResultSetImpl.checkClosed(ResultSetImpl.java:794) at com.mysql.jdbc.ResultSetImpl.next(ResultSetImpl.java:7077) at server.util.Plimus$1.run(Plimus.java:77) 

这是在第77行： while (resultSet.next()) {

 public static void process(final Player c, final String playerName) { if (connection == null && connectionStatus == 0) createConnection(); else if (connectionStatus != 0) return; new Thread() { @Override public void run() { try { String username = playerName.replaceAll(" ", "_"); String query = "SELECT * FROM donations WHERE username = '" + username + "' AND received = '0' LIMIT 1;"; ResultSet resultSet = query(query); while (resultSet.next()) { int[] contractIds = {3178768, 1}; //put all of your contract ids in here. int contractId = Integer.parseInt(resultSet.getString("contract")), id = Integer.parseInt(resultSet.getString("id")); query("UPDATE donations SET received = '1' WHERE username = '" + username + "' AND id = '" + id + "';"); if (contractId == contractIds[0]) { //first contract id in array. c.getItems().addItem(962, 1); } else if (contractId == contractIds[1]) { //second contract id in array. c.getItems().addItem(962, 1); } } } catch (Exception e) { e.printStackTrace(); processMethod(0, true, true, false); } } }.start(); } 

这是请求的查询方法。

 /** * Creates query function. */ public static ResultSet query(String s) throws SQLException { try { if (s.toLowerCase().startsWith("select")) { ResultSet resultSet = statement.executeQuery(s); return resultSet; } else { statement.executeUpdate(s); } return null; } catch (Exception e) { e.printStackTrace(); processMethod(0, true, true, false); } return null; } 

Answer 1

在迭代ResultSet ，您将重用Statement对象来更新数据（在query方法中），从而从查询中关闭ResultSet 。

请参阅ResultSet文档 ：

“当生成它的Statement对象关闭，重新执行或用于从多个结果序列中检索下一个结果时，ResultSet对象会自动关闭。”

您应该为查询和更新创建单独的语句，并将它们传递给您的查询方法：

 public ResultSet query(String s, Statement statement) throws SQLException { ... } 

我假设该statement在类中statement为static – 通常不需要：在类的构造函数中创建用于查询和更新的两个语句，并将它们传递给query()方法或使用一个或者其他取决于声明。