java oracle 数据库

程序运行会报 关闭的语句: next 错误，请高手指正，谢谢！1、TEST类，启动两个线程。package main;public class Test {public static void main(String[] args){TestThread t1 =new TestThread();t1.setName("T1 ");t1.start();TestThread t2 =new TestThread();t2.setName("T2 ");t2.start();}}2、线程类package main;import java.sql.ResultSet;public class TestThread extends Thread {int i = 0;public void run() {while (i < 20) {i++;try {ResultSet rs = Controller.getInstance().getDB().Query("select SYSTIMESTAMP from dual");while (rs.next())System.out.println(rs.getString(1));System.out.println(this.getName() + i);Thread.sleep(10);} catch (Exception e) {System.out.println(this.getName() + i + " " + e.getMessage());}}}}3、控制类package main;import datebase.OraPooledSQL;public class Controller {static Controller Instance = new Controller();private OraPooledSQL DB = new OraPooledSQL();public static Controller getInstance() {return Instance;}public OraPooledSQL getDB() {return DB;}}4、数据库操作类package datebase;import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import javax.sql.PooledConnection;import oracle.jdbc.pool.OracleConnectionPoolDataSource;public class OraPooledSQL {private PooledConnection dbpool;public OraPooledSQL() {try {String ConnectionURL = "jdbc:oracle:thin:@127.0.0.1:1521:XE";String UserID = "ivruser";String PassWord = "ivruser123";OracleConnectionPoolDataSource ocpds = new OracleConnectionPoolDataSource();ocpds.setURL(ConnectionURL);ocpds.setUser(UserID);ocpds.setPassword(PassWord);dbpool = ocpds.getPooledConnection();} catch (Exception ex) {System.err.println("Error in PooledSQL-construct ");ex.printStackTrace(System.err);}}protected void finalize() {if (dbpool != null) {try {System.out.println("finalize");dbpool.close();} catch (Exception ex) {}}}public synchronized ResultSet Query(String SQL) throws SQLException {Statement stmt = null;ResultSet rs = null;Connection connection = null;connection = dbpool.getConnection();stmt = connection.createStatement();rs = stmt.executeQuery(SQL);return rs;}}