Question

我正在使用eclipse为项目实现一段代码。我被要求做的一个功能是找出数据库表中是否有两个值（用h2创建）。所有这些必须通过使用DAO类和在main和DAO类之间传递的Manager类来实现。我的问题是，通过这样做，总会引发一个异常，告诉我没有找到“数据包列表”表。但这不可能是因为：

我在数据库中检查了它并且有表
数据库与eclipse正确连接
如果我实现了main中的所有功能，表格就被识别了！

这些是类：

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DaoPacchetti {


public static boolean Ricerca(String citta, String periodo ) throws SQLException{
    boolean verifica=false;
    PreparedStatement stat=null;
    ResultSet rs=null;
    Connection con=null;


    con= DBManager.getConnection();
    stat=con.prepareStatement("SELECT * FROM pacchettivisiteturistiche "
            +  " WHERE citta=? AND disponibilitaSottoscrizione=?");
    stat.setString(1, citta);
    stat.setString(2, periodo);
    rs=stat.executeQuery();
    if(rs.next()){
        verifica=true;
    }

    //rs.close();
    //stat.close();
    con.close();
    return verifica;

    } 
}

经理班级：

import dao.DaoPacchetti;
//import dao.DAOException;
import java.sql.SQLException;



public class GestorePacchetti {

private static GestorePacchetti istance;

public static GestorePacchetti getIstance() {
    if (istance == null)
        istance = new GestorePacchetti();
    return istance;
}

public  boolean RicercaPacchetto(String citta,String periodo){
    boolean trovato=false;
    try{
    trovato=DaoPacchetti.Ricerca(citta, periodo);
    return trovato;
    }
    catch(SQLException e){
        System.err.println("errore nella ricerca del pacchetto");
        e.printStackTrace();
    }

    return trovato;
}
}

主要课程：

import pacchetti.GestorePacchetti;
import java.util.Scanner;

public class Terminale {

public static void main(String[] args) {


    boolean trovato;
    String citta;
    String codice_pacchetto;
    String data;
    String nPartecipantistringa;
    int nPartecipanti;

    GestorePacchetti g=  GestorePacchetti.getIstance();

System.out.println("immetti la città e la data per la ricerca del pacchetto 
delle visite turistiche");

    Scanner input = new Scanner(System.in);

    do{
        System.out.println("immetti prima la citta");
        citta = input.nextLine();
        System.out.println("ora immetti la data");
        data=input.nextLine();

        trovato=g.RicercaPacchetto(citta, data);


        if(trovato==false)
        System.out.println("Reinserire i parametri per favore");
    }while(trovato==false);

    System.out.println("Trovato!!");

}

}

我还编写了包含整个函数的main函数，而不调用其他类（这里的表被识别）：

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;


public class Main {

public static void main(String[] args) throws Exception{

    boolean trovato;
    String citta;
    String codice_pacchetto;
    String data;
    String nPartecipantistringa;
    int nPartecipanti;

    GestoreVisiteTuristiche g= new GestoreVisiteTuristiche();

    System.out.println("immetti la città e la data per la ricerca del 
    pacchetto delle visite turistiche");

    Scanner input = new Scanner(System.in);


        System.out.println("immetti prima la citta");
        citta = input.nextLine();
        System.out.println("ora immetti la data");
        data=input.nextLine();

        Connection con=null;
        PreparedStatement stat=null;
        ResultSet rs=null;

        try{


        con=DBManager.getConnection();
        stat=con.prepareStatement("SELECT * FROM PacchettiVisiteTuristiche P 
"
                +  "WHERE ?=P.citta AND ?=P.disponibilitaSottoscrizione");
        stat.setString(1, citta);
        stat.setString(2, data);
        rs=stat.executeQuery();

        if(rs.next()){
            System.out.println("trovato!!");
            citta=rs.getString("citta");
            data=rs.getString("disponibilitaSottoscrizione");
            System.out.println(citta+" "+data);
        }
        else{
            System.out.println("errore, nessuna corrispondenza");
        }

        rs.close();
        stat.close();
        }
        catch(Exception e){System.out.println("errore");}
        finally {
            if (con != null) {
        try {
            con.close();
        } catch (SQLException e){}
        }
        }





}
}

DBManager上课：

import java.sql.Connection;


public class DBManager {
protected static Connection conn;

final protected static ConnectionFactory CONNECTION_FACTORY=new 
H2ConnectionFactory();

public static Connection getConnection(){
    if (conn == null) {
        try {
            conn = CONNECTION_FACTORY.createConnection();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
    return conn;

}
}

ConnectionFactory：

public interface ConnectionFactory {
java.sql.Connection createConnection() throws Exception;
}

import java.sql.DriverManager;


public class H2ConnectionFactory implements ConnectionFactory { 

protected final static String DB_PATH= "./test";
protected final static String CONNECTION_STRING = "jdbc:h2:" + DB_PATH ;


@Override
public java.sql.Connection createConnection() throws Exception {
    Class.forName("org.h2.Driver");
    return DriverManager.getConnection(CONNECTION_STRING, "sa", "12345");
}
}

这是引发的例外：

org.h2.jdbc.JdbcSQLException: Table "PACCHETTIVISITETURISTICHE" not found; 
SQL statement:
SELECT * FROM pacchettivisiteturistiche  WHERE citta=? AND 
disponibilitaSottoscrizione=? [42102-195]
at org.h2.message.DbException.getJdbcSQLException(DbException.java:345)
at org.h2.message.DbException.get(DbException.java:179)
at org.h2.message.DbException.get(DbException.java:155)
at org.h2.command.Parser.readTableOrView(Parser.java:5506)
at org.h2.command.Parser.readTableFilter(Parser.java:1260)
at org.h2.command.Parser.parseSelectSimpleFromPart(Parser.java:1940)
at org.h2.command.Parser.parseSelectSimple(Parser.java:2089)
at org.h2.command.Parser.parseSelectSub(Parser.java:1934)
at org.h2.command.Parser.parseSelectUnion(Parser.java:1749)
at org.h2.command.Parser.parseSelect(Parser.java:1737)
at org.h2.command.Parser.parsePrepared(Parser.java:448)
at org.h2.command.Parser.parse(Parser.java:320)
at org.h2.command.Parser.parse(Parser.java:292)
at org.h2.command.Parser.prepareCommand(Parser.java:257)
at org.h2.engine.Session.prepareLocal(Session.java:573)
at org.h2.engine.Session.prepareCommand(Session.java:514)
at org.h2.jdbc.JdbcConnection.prepareCommand(JdbcConnection.java:1204)
at org.h2.jdbc.JdbcPreparedStatement.<init>(JdbcPreparedStatement.java:73)
at org.h2.jdbc.JdbcConnection.prepareStatement(JdbcConnection.java:288)
at dao.DaoPacchetti.Ricerca(DaoPacchetti.java:22)
at pacchetti.GestorePacchetti.RicercaPacchetto(GestorePacchetti.java:21)
at ui.Terminale.main(Terminale.java:30)

Answer 1

好的，但我不确定错误是否在这里因为在函数工作的主类中我使用相同的DBManager类。这是我的DBManager类：

import java.sql.Connection;


public class DBManager {
protected static Connection conn;

final protected static ConnectionFactory CONNECTION_FACTORY=new 
H2ConnectionFactory();

public static Connection getConnection(){
    if (conn == null) {
        try {
            conn = CONNECTION_FACTORY.createConnection();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
    return conn;

}
}

这是ConnectorFactory的接口和类：

public interface ConnectionFactory {
java.sql.Connection createConnection() throws Exception;
}

import java.sql.DriverManager;


public class H2ConnectionFactory implements ConnectionFactory { 

protected final static String DB_PATH= "./test";
protected final static String CONNECTION_STRING = "jdbc:h2:" + DB_PATH ;


@Override
public java.sql.Connection createConnection() throws Exception {
    Class.forName("org.h2.Driver");
    return DriverManager.getConnection(CONNECTION_STRING, "sa", "12345");
}
}

Answer 2

jdbc:h2:~/test","sa","password" 或 jdbc:h2:file:~/test;USER=sa;PASSWORD=password

尝试任何这些连接字符串。

org.h2.jdbc.JdbcSQLException：未找到表“PACCHETTIVISITETURISTICHE”; SQL语句：

2 个答案: