Java JPA和Java JDBC对于相同的MySQL查询返回不同的结果

Question

NOTE: I know there's a lot of code in here but you probably just need to look to the first 2 code blocks.

I've a query and from the results from that query I build an ArrayList of Station objects, ArrayList<Station> .

I want to use JPA as it is more flexible to use on the long run, so I'm adapting my code to run on JPA.

So I give a list of Station objects to a method and this method will do some calculations and do station.setPingPong(); if that station meets certain calculation criteria, not relevant to the question.

The problem is the list from JPA originates 3871 PingPongs and the list from JDBC originates 3888 PingPongs, the correct one is 3888. Why this?

Here's my code where I build the objects with the data from the database:

for (int i = 0; i < uniqueStations.size(); i++) 
{

ArrayList<Station> stationDataList = new ArrayList<>();
ArrayList<Station> auxStationDataList = new ArrayList<>();
ArrayList<Station> pingPongProccessedData = new ArrayList<>();
ArrayList<Station> pingPongProccessedDataJPA = new ArrayList<>();

// Query using JDBC
String queryToApi = "SELECT * "
                    + "FROM " + readTable + " "
                    + "WHERE calling_station_id = '" + uniqueStations.get(i) + "' "
                    + "order by timestamp-acct_session_time, timestamp;";

// Query using JPA                    
String query = "SELECT timestamp-acct_session_time, timestamp, called_station_id "
                + "FROM " + readTable + " "
                + "WHERE calling_station_id = '" + uniqueStations.get(i) + "' "
                + "order by timestamp-acct_session_time, timestamp;";

// Using JDBC, here Station objects are created inside getStationData method, inserted into the list and returned.
stationDataList = Database.getInstance().getStationData(api.getConnectionSourceServer(), query, false);

// Using JPA, JavaLogs is my Class Entity from the database (it represents my table and was generated by NetBeans)
List<JavaLogs> javaLogsList =  api.executeSelectQuery(queryToApi, JavaLogs.class, "TesteV2PU");
int repetitionSTA = 0;
// Now I'm creating the Station objects                    
for(JavaLogs javaLogs : javaLogsList)
{
    int id = javaLogs.getIdacesso();      
    long timestamp = javaLogs.getTimestamp();
    long accountSessionTime = javaLogs.getAcctSessionTime();
    int startTime = (int) (timestamp - accountSessionTime);
    int endTime = javaLogs.getTimestamp();
    String accessPoint = javaLogs.getCalledStationId();
    int ttPrevious = 0;
    int ttNext = 0;
    int pPong = 0;
    Station station = new Station(id, startTime, endTime, accessPoint, stationAnonymized++, repetitionSTA++, ttPrevious, ttNext, pPong);

    auxStationDataList.add(station);
}

// The problem comes here, pingPongProccessedData does have the correct computation of Station objects
// But pingPongProccessedDataJPA doesn't have the correct computation of Station objects
// In other words, pingPongProccessedDataJPA is WRONG and pingPongProccessedData is correct.

pingPongProccessedData = detectPingPong(accessThreshold, transitionThreshold, stationDataList);
pingPongProccessedDataJPA = detectPingPong(accessThreshold, transitionThreshold, auxStationDataList);

pingPongStationList.addAll(pingPongProccessedData);
pingPongStationListJPA.addAll(pingPongProccessedDataJPA);

}

int totalPingPongsJDBC = 0;
int totalPingPongsJPA = 0;

for(Station station : pingPongStationList) 
{
    if(station.getPingPong() == 1)
    {
        totalPingPongsJDBC++;
    }
}

for(Station station : pingPongStationListJPA) 
{
    if(station.getPingPong() == 1)
    {
        totalPingPongsJPA++;
    }
}

// Here I get in the console: TOTAL PingPongs JPA: 3871 TOTAL PingPongs JDBC: 3888
System.out.println("TOTAL PingPongs JPA: " + totalPingPongsJPA + " TOTAL PingPongs JDBC: " + totalPingPongsJDBC);

And here is my getStationData method from my Databse Object:

public ArrayList<Station> getStationData(Connection con, String query, boolean isStationAnonymizeRequired) throws SQLException
{
    ArrayList<Station> stationList = new ArrayList<>();

    Statement s = con.createStatement();
    ResultSet rs = s.executeQuery(query);

    int repetitionSTA=1;

    while (rs.next()) 
    {
        /*
         * SQL Retorns:
         * StartTime - EndTime - AP - STA
         * 
         * Objecto Station:
         * ID - StartTime - EndTime - AP - STA - RepetitionSTA - TransitionTimePrevious - TransitionTimeNext - PingPong
         */

        if(isStationAnonymizeRequired == false)
        {
            Station station = new Station(id, rs.getInt(1), rs.getInt(2), rs.getString(3), stationMacAddress, repetitionSTA, 0, 0, 0);
            stationList.add(station);
            repetitionSTA++;
            id++;
        }
        else
        { //                            (id, startTime, endTime, ap, sta, repetitionSTA, ttprevious, ttnext, ppong)
            Station station = new Station(rs.getInt(1), rs.getInt(2), rs.getInt(3), rs.getString(4),
                    rs.getInt(5), repetitionSTA, rs.getInt(6), rs.getInt(7), rs.getInt(8));
            stationList.add(station);
            repetitionSTA++;
        }
    }
    rs.close();
    s.close();
    stationMacAddress++;

    return stationList;
}

I know that the IDs are different, built differently but that has no problem because the IDs are not used in detectPingPong method.

Just in case, here's my detectPingPong method:

public ArrayList<Station> detectPingPong(int accessSessionTime, int transitionTime, ArrayList<Station> stationDataList)
{

    for(int i = 1; i<stationDataList.size()-1; i++) //i=1 to skip the first position and -1 to skip the last position
    {
        /*
         * StartTime - EndTime - AP - STA - TTprevious - TTnext - PPong - ID
         */

        /*
         * At current position values
         */
        int startTimeActual = stationDataList.get(i).getStartTime();
        int endTimeActual = stationDataList.get(i).getEndTime();
        String apActual = stationDataList.get(i).getAccessPoint();

        /*
         * get the values from the previous position
         * */ 
        int endTimePrevious = stationDataList.get(i-1).getEndTime();
        String apPrevious = stationDataList.get(i-1).getAccessPoint();

        /*
         * get the values from the next position
         * */
        int startTimeNext = stationDataList.get(i+1).getStartTime();
        String apNext = stationDataList.get(i+1).getAccessPoint();     


        //Calc transition times:
        int transitionTimePrevious = startTimeActual - endTimePrevious;
        int transitionTimeNext = startTimeNext - endTimeActual;

        stationDataList.get(i).setTransitionTimePrevious(transitionTimePrevious);
        stationDataList.get(i).setTransitionTimeNext(transitionTimeNext);


         /*
          * Testing the conditions to occur a pingpong
          * */
        if(transitionTimePrevious<0)
        {
            transitionTimePrevious=0;
            stationDataList.get(i).setTransitionTimePrevious(transitionTimePrevious);
        }


        if(transitionTimeNext<0)
        {
            transitionTimeNext=0;
            stationDataList.get(i).setTransitionTimeNext(transitionTimeNext);
        }


        /*
         * ***************************
         * *    TEST PING PONG       *
         * ***************************
         */


        if( endTimeActual - startTimeActual < accessSessionTime && 
                transitionTimePrevious < transitionTime &&
                transitionTimeNext < transitionTime &&
                apActual.equalsIgnoreCase(apPrevious) == false &&
                stationDataList.get(i).getRepetitionSTA() > 1 
           )
        {
            stationDataList.get(i).setPingPong();
        }

    }
    return stationDataList;
}

So, as the method ( detectPingPong ) is the same for both lists and I get different results I assume that the error is on the lists, therefore the objects in the list which leads to the construction of the objects.

Answer 1

You are mapping the results to a bean class( javalogs ). Probably there is some retreived data that doesnot match with the JavaLogs fields. Those retreived rows will be ignored. And that is why you see discrepancy between the results.