Question

我有这段代码，我在数据库（mysql）中获取一些数据，并将其存储在多维hashmap中。但是＆＃34;节目＆＃34; part在每次迭代中都是相同的，尽管我每次迭代都会创建一个新的hashmap。

它是＆＃34; idProgram＆＃34;我认为导致问题的hashmap; s

以下是代码：

public static String epg() {
    Connection con = null;
    PreparedStatement pst = null;
    ResultSet rs = null;
    PreparedStatement pst2 = null;
    ResultSet rs2 = null;
    Date dNow = new Date();

    SimpleDateFormat ft = new SimpleDateFormat ("yyyyMMdd");
    String time = ft.format(dNow).toString();
    String json = "[";
    String url = "jdbc:mysql://" + main_server.ipSQL + ":" + main_server.portSQL + "/" + main_server.dbExtra;
    try {
        con = DriverManager.getConnection(url, main_server.userSQL, main_server.passwordSQL);
        pst = con.prepareStatement("SELECT idChannel, channelName, logoPath, macro FROM channel");
        rs = pst.executeQuery();
        Gson gson = new GsonBuilder().create();
        while (rs.next()) { 
            LinkedHashMap<String, Object> channels = new LinkedHashMap<String, Object>();
            LinkedHashMap<Integer,Object> idProgram = new LinkedHashMap<Integer,Object>();
            channels.put("idChannel", rs.getString(1));
            channels.put("channelName", rs.getString(2));
            channels.put("logoPath", rs.getString(3));
            channels.put("macro", rs.getString(4));
            pst2 = con.prepareStatement("SELECT idProgram, title, start, stop, category, episodeNumber FROM program WHERE start LIKE '"+time+"%'");
            rs2 = pst2.executeQuery();
            while (rs2.next()) { 
                LinkedHashMap<String, Object> channels2 = new LinkedHashMap<String, Object>();
                int duration = Integer.parseInt(rs2.getString(4).substring(8, 12)) - Integer.parseInt(rs2.getString(3).substring(8, 12));
                channels2.put("title", StringEscapeUtils.unescapeJava(rs2.getString(2)));
                channels2.put("category", StringEscapeUtils.unescapeJava(rs2.getString(5)));
                channels2.put("episodeNumber", rs2.getString(6));
                channels2.put("start", rs2.getLong(4));
                channels2.put("duration", duration);
                idProgram.put(rs2.getInt(1), channels2);
            }  
            channels.put("programs", idProgram);
            json = json + gson.toJson(channels) + ",";
        }  
        json = json.substring(0, json.length() - 1) + "]";
    } catch (SQLException ex) {
        Logger lgr = Logger.getLogger(sql.class.getName());
        lgr.log(Level.SEVERE, ex.getMessage(), ex);
    } finally {
        try {
            if (rs != null) {
                rs.close();
            }
            if (pst != null) {
                pst.close();
            }
            if (con != null) {
                con.close();
            }
        } catch (SQLException ex) {
            Logger lgr = Logger.getLogger(sql.class.getName());
            lgr.log(Level.WARNING, ex.getMessage(), ex);
        }
    }
    try {
        BufferedWriter out = new BufferedWriter(new FileWriter("file.txt"));
        out.write(json);
        out.close();
    } catch (IOException e) {}
    return json;
}

修改

此代码输出：

[
{
"idChannel": "1",
"channelName": "DR1 HD",
"logoPath": "/media/channel_logo/1.jpg",
"macro": "TV,1,ENTER",
"programs": {
  "55483": {
    "title": "Drivhusdrømme",
    "category": "documentary, serie",
    "episodeNumber": " .2/6. ",
    "start": 20130505065500,
    "duration": 30
  },
  "55484": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .10/320. ",
    "start": 20130505072000,
    "duration": 65
  },
  "55485": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .11/320. ",
    "start": 20130505075000,
    "duration": 30
  },
  "55486": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .12/320. ",
    "start": 20130505081500,
    "duration": 65
  },
  "55487": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .13/320. ",
    "start": 20130505084000,
    "duration": 25
  },
  "55488": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .14/320. ",
    "start": 20130505091000,
    "duration": 70
  },
  "55489": {
    "title": "Downton Abbey III",
    "category": "serie",
    "episodeNumber": " .7/10. ",
    "start": 20130505101500,
    "duration": 105
  },
  "55490": {
    "title": "Downton Abbey III",
    "category": "serie",
    "episodeNumber": " .8/10. ",
    "start": 20130505110500,
    "duration": 90
  },
  "55491": {
    "title": "Kyst til kyst - Østjyllands kyst",
    "category": "entertainment, serie",
    "episodeNumber": " .2/8. ",
    "start": 20130505120500,
    "duration": 100
  },
  "55492": {
    "title": "OBS",
    "category": "news, serie",
    "start": 20130505121000,
    "duration": 5
  },
  "55493": {
    "title": "BingoBoxen",
    "category": "entertainment, serie",
    "start": 20130505122500,
    "duration": 15
  },
  "55494": {
    "title": "General Custers sidste kamp",
    "category": "movie",
    "start": 20130505144000,
    "duration": 215
  },
  "55495": {
    "title": "For godt til at være sandt",
    "category": "entertainment, serie",
    "start": 20130505150000,
    "duration": 60
  },
  "55496": {
    "title": "Miss Marple: Den gustne hest",
    "category": "movie",
    "start": 20130505163000,
    "duration": 130
  },
  "55497": {
    "title": "HåndboldSøndag: Team Tvis Holstebro-Metz Handball (k), direkte",
    "category": "sport",
    "start": 20130505183000,
    "duration": 200
  },
  "55498": {
    "title": "TV AVISEN  med Sporten og Vejret",
    "category": "news, serie",
    "start": 20130505190000,
    "duration": 70
  },
  "55499": {
    "title": "Menneskets planet",
    "category": "documentary, serie",
    "episodeNumber": " .7/8. ",
    "start": 20130505194500,
    "duration": 45
  },
  "55500": {
    "title": "Bag om Menneskets planet",
    "category": "documentary, serie",
    "episodeNumber": " .7/8. ",
    "start": 20130505200000,
    "duration": 55
  }
}
},{
"idChannel": "2",
"channelName": "TV2 HD",
"logoPath": "/media/channel_logo/2.jpg",
"macro": "TV,2,ENTER",
"programs": {
  "55483": {
    "title": "Drivhusdrømme",
    "category": "documentary, serie",
    "episodeNumber": " .2/6. ",
    "start": 20130505065500,
    "duration": 30
  },
  "55484": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .10/320. ",
    "start": 20130505072000,
    "duration": 65
  },
  "55485": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .11/320. ",
    "start": 20130505075000,
    "duration": 30
  },
  "55486": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .12/320. ",
    "start": 20130505081500,
    "duration": 65
  },
  "55487": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .13/320. ",
    "start": 20130505084000,
    "duration": 25
  },
  "55488": {
    "title": "Der er noget i luften",
    "category": "serie",
    "episodeNumber": " .14/320. ",
    "start": 20130505091000,
    "duration": 70
  },
  "55489": {
    "title": "Downton Abbey III",
    "category": "serie",
    "episodeNumber": " .7/10. ",
    "start": 20130505101500,
    "duration": 105
  },
  "55490": {
    "title": "Downton Abbey III",
    "category": "serie",
    "episodeNumber": " .8/10. ",
    "start": 20130505110500,
    "duration": 90
  },
  "55491": {
    "title": "Kyst til kyst - Østjyllands kyst",
    "category": "entertainment, serie",
    "episodeNumber": " .2/8. ",
    "start": 20130505120500,
    "duration": 100
  },
  "55492": {
    "title": "OBS",
    "category": "news, serie",
    "start": 20130505121000,
    "duration": 5
  },
  "55493": {
    "title": "BingoBoxen",
    "category": "entertainment, serie",
    "start": 20130505122500,
    "duration": 15
  },
  "55494": {
    "title": "General Custers sidste kamp",
    "category": "movie",
    "start": 20130505144000,
    "duration": 215
  },
  "55495": {
    "title": "For godt til at være sandt",
    "category": "entertainment, serie",
    "start": 20130505150000,
    "duration": 60
  },
  "55496": {
    "title": "Miss Marple: Den gustne hest",
    "category": "movie",
    "start": 20130505163000,
    "duration": 130
  },
  "55497": {
    "title": "HåndboldSøndag: Team Tvis Holstebro-Metz Handball (k), direkte",
    "category": "sport",
    "start": 20130505183000,
    "duration": 200
  },
  "55498": {
    "title": "TV AVISEN  med Sporten og Vejret",
    "category": "news, serie",
    "start": 20130505190000,
    "duration": 70
  },
  "55499": {
    "title": "Menneskets planet",
    "category": "documentary, serie",
    "episodeNumber": " .7/8. ",
    "start": 20130505194500,
    "duration": 45
  },
  "55500": {
    "title": "Bag om Menneskets planet",
    "category": "documentary, serie",
    "episodeNumber": " .7/8. ",
    "start": 20130505200000,
    "duration": 55
  }
}
}
]

所以第一部分正确输出了更改的数据..但是＆＃34;程序＆＃34;中的子图。每次迭代都会覆盖数据：（

Answer 1

是的，你绝对不想在每次迭代中声明一个新的HashMap。在外面声明并相应地插入您想要的数据

public static String epg() {
   Connection con = null;
   PreparedStatement pst = null;
   ResultSet rs = null;
   PreparedStatement pst2 = null;
   ResultSet rs2 = null;
   Date dNow = new Date();
   LinkedHashMap<String, Object> channels = new LinkedHashMap<String, Object>();
   LinkedHashMap<Integer,Object> idProgram = new LinkedHashMap<Integer,Object>();
   ...
   ...
   while (rs.next()) {
      channels.put("idChannel", rs.getString(1));
      channels.put("channelName", rs.getString(2));
      channels.put("logoPath", rs.getString(3));
      channels.put("macro", rs.getString(4))

Answer 2

您对pst2的查询总是相同的，当然每次都会提供相同的程序数据。您是否打算为每个频道更新“时间”？如果没有，该程序如何与您的频道相关，它们的共同密钥是什么？然后，应在pst2 SQL查询中使用此密钥来查询所需的密钥。

虽然每次迭代都会创建新映射，但Hashmaps会被覆盖

2 个答案: