如何使用Java代码将数据从Postgresql导出到mongoDB？

Question

我正在尝试将数据从Postgresql数据库导出到MongoDB。我已成功创建了JSON格式的字符串，当我将此json存储在mongoDB集合中时，仅存储第一个条目。 这是我的代码：public class jsonTobson {

    public static void main(String[] args) {

    Connection con = null;
    Statement st = null;

    try{
        Class.forName("org.postgresql.Driver");
        con = DriverManager.getConnection("jdbc:postgresql://localhost:5544/ddc", "postgres", "aman");
        st = con.createStatement();

        String sql = "select row_to_json(judge_info) FROM dp.judge_info order by judge_idno";

        ResultSet rs = st.executeQuery(sql);
        StringBuilder builder = new StringBuilder();
        int columnCount = rs.getMetaData().getColumnCount();

        while (rs.next()) {
            for (int i = 0; i < columnCount;) {
                builder.append(rs.getString(i + 1));
                if (++i < columnCount) builder.append(",");
            }
            builder.append("\r\n");
        }
        String resultSetAsString = builder.toString();



        MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
        DB db = mongoClient.getDB( "mongoTest" );
        DBCollection coll = db.getCollection("newTable");
        Set<String> colls = db.getCollectionNames();

        for (String s : colls) {
            System.out.println(s);
        }


    DBObject dbObject = (DBObject)JSON.parse(resultSetAsString);

    coll.insert(dbObject, WriteConcern.NORMAL);                     
        DBCursor cursorDocJSON = coll.find();
        while (cursorDocJSON.hasNext()) {
            System.out.println(cursorDocJSON.next());
        }       

            rs.close();
            st.close();
            con.close();
        } catch ( Exception e)
        {
            e.printStackTrace();
            System.err.println(e.getClass().getName()+": "+e.getMessage());
            System.exit(0);
        } finally {
        }


    }


}

Answer 1

    public static void main(String[] args) {

    Connection con = null;
    Statement st = null;

    try{
        Class.forName("org.postgresql.Driver");
        con = DriverManager.getConnection("jdbc:postgresql://localhost:5544/ddc", "postgres", "aman");
        st = con.createStatement();

        String sql = "select row_to_json(judge_info) FROM dp.judge_info order by judge_idno";

        ResultSet rs = st.executeQuery(sql);

        MongoClient mongoClient=null;
            try {
                mongoClient = new MongoClient("localhost", 27017);
            } catch (UnknownHostException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

        DB db = mongoClient.getDB("mongoTest");
        System.out.println("Connect to database successfully");

        while (rs.next()) {
                DBCollection coll = db.getCollection("newTable");
                System.out.println("Collection selected successfully");

                BasicDBObject doc = new BasicDBObject("data", rs.getString(1));

                coll.insert(doc);
                }
        } catch ( Exception e)
        {
            e.printStackTrace();
            System.err.println(e.getClass().getName()+": "+e.getMessage());
            System.exit(0);
        } finally {
        }
    }
}