Java GWT：试图通过GWT AsyncCallback检索对象列表我得到了一个只有最后一个值的列表

我正在尝试通过异步回调调用检索对象列表。在我查看onSuccess过程中的列表数据之前，一切看起来都很好。实际上，我收到了一个行数正确的列表，但每一行都与SQL语句最后检索的行数相同

这是入口点客户端模块：

package com.fantaprica.client;

import java.util.List;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.fantaprica.shared.GameDay;


/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class Fantaprica implements EntryPoint {

private final ODBConnectionAsync odbconnectionSvc = GWT
        .create(ODBConnection.class);

/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */

public void onModuleLoad() {

    odbconnectionSvc
            .getGameDayList(new AsyncCallback<List<GameDay>>() {
                public void onFailure(Throwable caught) {
                }

                public void onSuccess(List<GameDay> result) {

                    System.out.println("#########################################");
                    System.out.println("OnModuleLoad");
                    for (int i = 0; i < result.size(); i++) {
                        System.out.println("index="+i);
                        System.out.println("result.get(i).getGameDayCompetition()="+result.get(i).getGameDayCompetition());
                        System.out.println("result.get(i).getGameDayCupFl()"+result.get(i).getGameDayCupFl());
                        System.out.println("result.get(i).getGameDayId()="+result.get(i).getGameDayId());
                        System.out.println("result.get(i).getGameDayOrder()="+result.get(i).getGameDayOrder());                                         
                        System.out.println("result.get(i).getGameDaySeason()="+result.get(i).getGameDaySeason());
                    }
                }
            });
}
}

这是服务器端的实现：

package com.fantaprica.server;

import java.text.ParseException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Connection2DB {

public static ResultSet resultset(String p_sql_statement) throws ParseException {

    //String db_file_name_prefix = "/home/dario/workspace/fantaprica/src/com/fantaprica/server/database/database";
    //String db_file_name_prefix = "/home/dario/workspace/fantaprica/war/database/database";
    String db_file_name_prefix = "/home/dario/Workspace/Fantaprica/war/fantaprica/database/database";
    Connection con = null;

    // connect to the database. This will load the db files and start the
    // database if it is not alread running.
    // db_file_name_prefix is used to open or create files that hold the
    // state
    // of the db.
    // It can contain directory names relative to the
    // current working directory
    try {
        Class.forName("org.hsqldb.jdbcDriver");
        con = DriverManager.getConnection("jdbc:hsqldb:file:"
                + db_file_name_prefix, // filenames prefix
                "sa", // user
                ""); // pass
        Statement statement = con.createStatement();
        ResultSet rs = statement.executeQuery(p_sql_statement);
        System.out.println("query "+p_sql_statement+" eseguita");
        statement.close();
        con.close();
        return rs;
    } catch (ClassNotFoundException ex) {
        Logger.getLogger(TestConnection.class.getName()).log(Level.SEVERE,
                null, ex);
        System.out.println("errore "+ex.toString());
        return null;
    } catch (SQLException ex) {
        Logger.getLogger(TestConnection.class.getName()).log(Level.SEVERE,
                null, ex);
        ex.printStackTrace();
        System.out.println("errore "+ex.toString());
        return null;
    }

}

public static void  execstmt(String p_sql_statement) throws ParseException {

    String db_file_name_prefix = "/home/dario/Workspace/Fantaprica/war/fantaprica/database/database";
    Connection con = null;

    // connect to the database. This will load the db files and start the
    // database if it is not alread running.
    // db_file_name_prefix is used to open or create files that hold the
    // state
    // of the db.
    // It can contain directory names relative to the
    // current working directory
    try {
        Class.forName("org.hsqldb.jdbcDriver");
        con = DriverManager.getConnection("jdbc:hsqldb:file:"
                + db_file_name_prefix, // filenames prefix
                "sa", // user
                ""); // pass
        Statement statement = con.createStatement();
        statement.executeUpdate(p_sql_statement);

        System.out.println("statement "+p_sql_statement+" eseguito");

        statement.close();
        con.close();

    } catch (ClassNotFoundException ex) {
        Logger.getLogger(TestConnection.class.getName()).log(Level.SEVERE,
                null, ex);
        System.out.println("errore "+ex.toString());

    } catch (SQLException ex) {
        Logger.getLogger(TestConnection.class.getName()).log(Level.SEVERE,
                null, ex);
        ex.printStackTrace();
        System.out.println("errore "+ex.toString());
    }

}

}

当我运行代码时，我会得到以下结果：

#########################################
ODBConnectionImpl
Start creating the list
scanning resultset
v_game_day_tmp.getGameDayCompetition()=campionato
v_game_day_tmp.getGameDayCupFl()=false
v_game_day_tmp.getGameDayId()=0
v_game_day_tmp.getGameDayOrder()15
v_game_day_tmp.getGameDaySeason()2012/2013
0
index=0
v_game_day_list.get(i).getGameDayCompetition()=campionato
v_game_day_list.get(i).getGameDayCupFl()=false
v_game_day_list.get(i).getGameDayId()=0
v_game_day_list.get(i).getGameDayOrder()=15
v_game_day_list.get(i).getGameDaySeason()=2012/2013
scanning resultset
v_game_day_tmp.getGameDayCompetition()=campionato
v_game_day_tmp.getGameDayCupFl()=false
v_game_day_tmp.getGameDayId()=1
v_game_day_tmp.getGameDayOrder()14
v_game_day_tmp.getGameDaySeason()2012/2013
1
index=1
v_game_day_list.get(i).getGameDayCompetition()=campionato
v_game_day_list.get(i).getGameDayCupFl()=false
v_game_day_list.get(i).getGameDayId()=1
v_game_day_list.get(i).getGameDayOrder()=14
v_game_day_list.get(i).getGameDaySeason()=2012/2013
scanning resultset
v_game_day_tmp.getGameDayCompetition()=campionato
v_game_day_tmp.getGameDayCupFl()=false
v_game_day_tmp.getGameDayId()=2
v_game_day_tmp.getGameDayOrder()13
v_game_day_tmp.getGameDaySeason()2012/2013
2
index=2
v_game_day_list.get(i).getGameDayCompetition()=campionato
v_game_day_list.get(i).getGameDayCupFl()=false
v_game_day_list.get(i).getGameDayId()=2
v_game_day_list.get(i).getGameDayOrder()=13
v_game_day_list.get(i).getGameDaySeason()=2012/2013
scanning resultset
v_game_day_tmp.getGameDayCompetition()=mundialito
v_game_day_tmp.getGameDayCupFl()=false
v_game_day_tmp.getGameDayId()=3
v_game_day_tmp.getGameDayOrder()12
v_game_day_tmp.getGameDaySeason()2012/2013
3
index=3
v_game_day_list.get(i).getGameDayCompetition()=mundialito
v_game_day_list.get(i).getGameDayCupFl()=false
v_game_day_list.get(i).getGameDayId()=3
v_game_day_list.get(i).getGameDayOrder()=12
v_game_day_list.get(i).getGameDaySeason()=2012/2013
list created
#########################################
OnModuleLoad
index=0
result.get(i).getGameDayCompetition()=mundialito
result.get(i).getGameDayCupFl()false
result.get(i).getGameDayId()=3
result.get(i).getGameDayOrder()=12
result.get(i).getGameDaySeason()=2012/2013
index=1
result.get(i).getGameDayCompetition()=mundialito
result.get(i).getGameDayCupFl()false
result.get(i).getGameDayId()=3
result.get(i).getGameDayOrder()=12
result.get(i).getGameDaySeason()=2012/2013
index=2
result.get(i).getGameDayCompetition()=mundialito
result.get(i).getGameDayCupFl()false
result.get(i).getGameDayId()=3
result.get(i).getGameDayOrder()=12
result.get(i).getGameDaySeason()=2012/2013
index=3
result.get(i).getGameDayCompetition()=mundialito
result.get(i).getGameDayCupFl()false
result.get(i).getGameDayId()=3
result.get(i).getGameDayOrder()=12
result.get(i).getGameDaySeason()=2012/2013

如您所见，该列表是在ODBConnectionImpl中正确创建的，由4行组成。 但是，当我扫描返回到AsyncCallback调用的列表时，我有四行相等的数据，它们都等于ResultSet中的最后一行

谢谢你的帮助和建议，

---

达里奥

新噪音，SHiv16，很抱歉，我复制粘贴错误。这是getGameDayList程序的代码

public List<GameDay> getGameDayList() {
    // TODO Auto-generated method stub

    List<GameDay> v_game_day_list = new ArrayList<GameDay>();
    GameDay v_game_day_tmp = new GameDay();
    String v_sql_statement;

    try {

        v_sql_statement = "SELECT T1.\"game_day_id\",T1.\"game_day_date\",T1.\"game_day_competition\","
                + " T1.\"game_day_season\",T1.\"game_day_cup_fl\",T1.\"game_day_order\""
                + " FROM \"game_days\" T1 ORDER BY T1.\"game_day_order\" DESC";
        System.out.println("   -------   -------   -------");
        System.out.println("classe ODBConnectionImpl");
        System.out.println("getGameDayList");
        System.out.println("esecuzione statement " + v_sql_statement);
        ResultSet rs = Connection2DB.resultset(v_sql_statement);
        System.out.println("query eseguita");

        int i = 0;

        System.out.println("#########################################");
        System.out.println("ODBConnectionImpl");
        System.out.println("Start creating the list");

        while (rs.next()) {
            v_game_day_tmp.getGameDay(rs.getDate("game_day_date"),
                    rs.getString("game_day_competition"),
                    rs.getString("game_day_season"),
                    rs.getBoolean("game_day_cup_fl"),
                    rs.getInt("game_day_id"), rs.getInt("game_day_order"));

            System.out.println("scanning resultset");
            System.out.println("v_game_day_tmp.getGameDayCompetition()="+v_game_day_tmp.getGameDayCompetition());
            System.out.println("v_game_day_tmp.getGameDayCupFl()="+v_game_day_tmp.getGameDayCupFl());
            System.out.println("v_game_day_tmp.getGameDayId()="+v_game_day_tmp.getGameDayId());
            System.out.println("v_game_day_tmp.getGameDayOrder()"+v_game_day_tmp.getGameDayOrder());
            System.out.println("v_game_day_tmp.getGameDaySeason()"+v_game_day_tmp.getGameDaySeason());
            System.out.println(i);

            v_game_day_list.add(v_game_day_tmp);

            System.out.println("index="+i);
            System.out.println("v_game_day_list.get(i).getGameDayCompetition()="+v_game_day_list.get(i).getGameDayCompetition());
            System.out.println("v_game_day_list.get(i).getGameDayCupFl()="+v_game_day_list.get(i).getGameDayCupFl());
            System.out.println("v_game_day_list.get(i).getGameDayId()="+v_game_day_list.get(i).getGameDayId());
            System.out.println("v_game_day_list.get(i).getGameDayOrder()="+v_game_day_list.get(i).getGameDayOrder());
            System.out.println("v_game_day_list.get(i).getGameDaySeason()="+v_game_day_list.get(i).getGameDaySeason());

            i++;

        }

        for(i=0;i<v_game_day_list.size();i++)
            System.out.println("secondo loop v_game_day_list.get(i).getGameDayId()="+v_game_day_list.get(i).getGameDayId());


        System.out.println("list created");
        return v_game_day_list;

    } catch (SQLException e) {
        System.out.println("ODBConnectionImpl SQLException: "
                + e.toString());
        return null;
    } catch (ParseException e) {
        System.out.println("ODBConnectionImpl ParseException: "
                + e.toString());
        return null;
    }

}

我读到问题可能是thr类属性的“静态”实现，而不是这种情况，因为GameDay类没有静态属性

---

Dario

我认为问题在于getGameDayList中的代码：

List<GameDay> v_game_day_list = new ArrayList<GameDay>();
GameDay v_game_day_tmp = new GameDay();
String v_sql_statement;

List v_game_day_List=new ArrayList（）；
GameDay v_game_day_tmp=新游戏日（）；
字符串v_sql_语句；

从这段代码中删除GameDay v_game_day_tmp=new GameDay（）

您所做的是在列表中使用同一对象（v_game_day_tmp）4次。当while循环重新填充v_game_day_tmp并添加到列表中时，列表中以前的条目仍然引用相同的对象（v_game_day_tmp），因此必然具有相同的值

不要使用1个临时对象

必须使用new（）重新创建该对象，填充该对象，然后将其添加到列表中

只需移动GameDay v_game_day_tmp=new GameDay（）；作为while的第一行（rs.next（））应该可以解决您的问题

---

问候。

我刚刚意识到这是一个与列表相关的问题，而不是异步回调调用。为什么最后添加的ELEMIND会覆盖所有其他ELEMIND？这不是相关的服务器代码。我看不到在那里创建的任何列表。另外：不要使用

语句.executeUpdate（p\u sql\u语句）进行正常的数据库查询！如果您可以发布ODBConnectionImpl.getGameDayList（）的代码，那会更有帮助。嗨，托马斯，谢谢你的回答，我认为一旦在列表中插入了一个对象，它就有了自己的“标识”。
List<GameDay> v_game_day_list = new ArrayList<GameDay>();
GameDay v_game_day_tmp = new GameDay();
String v_sql_statement;