how can I map the jdbc resultSet to user defined class generally?

Question

I have some problems that do the same function from 4gl to java. There are some brief explanation to 4gl code. First,AFPOPF1 is table,and IO_AFPOPF1 is variable that store contents of AFPOPF1. Excuting WK_QUERY and store row result to IO_AFPOPF1.* using 'FETCH SCUR_1 INTO IO_AFPOPF1.*' statement. After running 'FETCH SCUR_1 INTO IO_AFPOPF1.*',the cursor refer to next row. Excuting 2nd query that which statement contains IO_AFPOPF1.POLYN1 in while loop.

DEFINE IO_AFPOPF1 RECORD LIKE AFPOPF1.*
     .
     .
     .
WK_QUERY  = "SELECT * FROM AFPOPF1 WHERE PRTDAT='IO_FONLY.PRTDAT'
       " AND((FCERNO[2] = 'C' AND LENGTH(FCERNO) = 9)"
       " OR (FCERNO[3] = 'C' AND LENGTH(FCERNO) = 10))"
       " AND SOLIN1 LIKE '", BS_SOLIN1,"'"
       " ORDER BY POLYN1,FCERNO"     
     .
     .
     . 
PREPARE SSTM_1 FROM WK_QUERY 
DECLARE SCUR_1 SCROLL CURSOR 
FETCH SCUR_1 INTO IO_AFPOPF1.*

WHILE STATUS = 0
    SELECT DEPTWN INTO WK_DEPTWN FROM COMLIB:DEPTPF1 
    WHERE DEPTNO = IO_AFPOPF1.POLYN1
    .
    .
    .
    IF WK_DEPTWN != IO_FONLY.DEPTWN
       FETCH SCUR_1 INTO IO_AFPOPF1.*
       CONTINUE  WHILE
    ELSE
       LET SW_COUNT = SW_COUNT+1   
    END  IF
    .
    .
    .
    FETCH SCUR_1 INTO IO_AFPOPF1.*
END WHILE

java:

//the class mapping to Afpopf1 Table
public class TableAfpopf1 {
   private String fcerno;//var1
   private String polyn1;//var2
      .
      .
      .
   private Date chkdat;//var58  

   public void setXXX
      .
      .
      .
}

//database connection anf return resultSet  
public class DBConnection {
    private Connection connection;
    private Statement statement;
    private PreparedStatement preS;
    private ResultSet resultSet;
    private boolean hasRow;
    private boolean isReturn;   
    private String dbURL;
    private ArrayList<ArrayList<Object>> allResultList;
    private Object returnObj;

    public DBConnection() {
        this.connection = null;
        this.statement = null;
        this.preS = null;
        this.resultSet = null;
        this.hasRow = false;
        this.isReturn = false;
        this.dbURL = "";        
        this.allResultList =  new ArrayList<ArrayList<Object>>();
    }

public void connectDB(String query) {
    try {            
        statement = connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);

        if (query.contains("SELECT"))
            resultSet = statement.executeQuery(query);

        ResultSetMetaData metaData = resultSet.getMetaData();
        int numberOfColumns = metaData.getColumnCount();

        while (resultSet.next()) {
           hasRow = true;
           if (isReturn) {                 
               if (numberOfColumns == 1) {
                  resultSet.last();
                  int rowCount = resultSet.getRow();
                  resultSet.first();

                  if (rowCount == 1)                          
                      returnObj = resultSet.getObject(1);                                             
               }
               else {
                   ArrayList<Object> arrayResultSet = new ArrayList<Object>();
                   for (int i = 1; i <= numberOfColumns; i++) {
                       arrayResultSet.add(resultSet.getObject(i));                         
                   }                       
                   allResultList.add(arrayResultSet);                      
               }                 
           }
           else                    
               break;                  
          }          
    }
    catch (SQLException sqlEx) {
        while(sqlEx != null) {
            System.err.println("SQLException information");
            System.err.println("Error msg: " + sqlEx.getMessage());
            System.err.println("SQLSTATE: " + sqlEx.getSQLState());
            System.err.println("Error code: " + sqlEx.getErrorCode());
            sqlEx.printStackTrace();
            sqlEx = sqlEx.getNextException();
       }
    }        
    finally {
        try {
            resultSet.close();
            statement.close();            
        }
        catch (Exception e) {
            e.printStackTrace();
        }    
    }                      
}

public void preQueryConnectDB(String query,String expression) {
    try {               
        preS = connection.prepareStatement(query,ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
        preS.setString(1, query);
        resultSet = preS.executeQuery();            
        ResultSetMetaData metaData = resultSet.getMetaData();
        int numberOfColumns = metaData.getColumnCount();            

        while (resultSet.next()) {              
            hasRow = true;
            if (isReturn) {                 
                if (numberOfColumns == 1) {
                    resultSet.last();
                    int rowCount = resultSet.getRow();
                    resultSet.first();

                    if (rowCount == 1)                          
                        returnObj = resultSet.getObject(1);                                             
                }
                else {
                    ArrayList<Object> arrayResultSet = new ArrayList<Object>();
                    for (int i = 1; i <= numberOfColumns; i++) {
                         arrayResultSet.add(resultSet.getObject(i));     
                    }                          
                    allResultList.add(arrayResultSet);                      
               }                  
            }
            else                 
                break;                
        }            
    }catch (SQLException sqlEx) {
        while(sqlEx != null) {
            System.err.println("SQLException information");
            System.err.println("Error msg: " + sqlEx.getMessage());
            System.err.println("SQLSTATE: " + sqlEx.getSQLState());
            System.err.println("Error code: " + sqlEx.getErrorCode());
            sqlEx.printStackTrace();
            sqlEx = sqlEx.getNextException();
        }
    }       
    finally {
       try {
           resultSet.close();
           preS.close();                
        }
        catch (Exception e) {
           e.printStackTrace();
        }   
    }                     
}

public void closeDBConnection() { 
    try {
        connection.close();             
    }
    catch (Exception e) {
        e.printStackTrace();
    }   
}

public void setIsReturnData(boolean isReturn) { this.isReturn = isReturn; }

public void setConnectionURL(String query) {
    String dbName = "";
    String newURL = "";
    int beginIndex = -1; //string from in index is positive
    int endIndex = -1;  //string : in index is positive
    beginIndex = query.indexOf("FROM");
    endIndex = query.indexOf(":");
    dbName = query.substring(beginIndex+4, endIndex).trim();
    newURL = "jdbc:informix-sqli://hwae5500:shme5500/"+dbName+":INFORMIXSERVER=shme5500;";

    if (!newURL.equals(dbURL)) {
        dbURL = newURL;
        try {
            if (connection != null)
               connection.close();
               Class.forName("com.informix.jdbc.IfxDriver");
               connection = DriverManager.getConnection(dbURL);
        }catch (SQLException e) {
            e.printStackTrace();
        }
        catch(ClassNotFoundException drvEx) {
            System.out.println("Driver fail");
            drvEx.printStackTrace();
        }       
    }        
}

public void recoverDefultValue() {
    this.statement = null;
    this.preS = null;
    this.resultSet = null;
    this.hasRow = false;
    this.isReturn = false;      
    this.returnObj = null;      
}

public boolean getHasRow() { return hasRow; }

public Object getReturnObj(){ return returnObj; }

//get all resultSet in Object type
public ArrayList<ArrayList<Object>> getAllResultList() { return allResultList; }
}

//the class receive query result and process data
pubblic class DataProcessing {
      .
      .
      .
    public void generateInformation() {
      .
      .
      .
        sqlQuery = "SELECT * FROM AFFIL:AFPOPF1 WHERE PRTDAT="+"'"+dateStr+"'"+
           "AND FCERNO[2]='C' AND LENGTH(FCERNO)=9 "+
       "AND SOLIN1 LIKE '"+bs_SOLIN1+"' ORDER BY POLYN1,FCERNO";

        db.recoverDefultValue();
        db.setIsReturnData(true);
        db.setConnectionURL(sqlQuery);
        db.connectDB(sqlQuery);
        if (db.getHasRow()) {
           setDataList(db.getAllResultList(),1);//Object type to Afpopf1 type
           sw_DATA = true;                  
        }
        .
        .
        .
        if (codeStr.charAt(0) == '0') {             
            sqlQuery = "SELECT DEPTWN FROM COMLIB:DEPTPF1 WHERE DEPTNO=?";
            db.recoverDefultValue();
            db.setIsReturnData(true);
            db.setConnectionURL(sqlQuery);          
            for (TableAfpopf1 tafp : Afpopf1List) {             
                db.preQueryConnectDB(sqlQuery,tafp.getPolyn1());
                wk_DEPTWN = setVarwk_DEPTWN((String)db.getReturnObj());
            }           
         }
            .
            .
            .           
    }

private void setDataList(ArrayList<ArrayList<Object>> allResultList,int choiceNum)                                                              
{
    int inputindex = 0;
    DateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");        
    if (choiceNum == 1) {
        for (int i=0; i<allResultList.size(); i++) {                
            TableAfpopf1 afpItem = new TableAfpopf1();
            for (Object obj : allResultList.get(i)) {
                switch (inputindex+1) {
                case 1:
                    afpItem.setFcerno((String)obj);
                    break;
                case 2:
                    afpItem.setPolyn1((String)obj);
                    break;
                    .
                    .
                    .
                case 58:                            
                    try {
                        Date date = sdf.parse(obj.toString());
                        afpItem.setChkdat(date);                                
                    }
                    catch (Exception e) {
                       System.out.println("error appear");
                       e.printStackTrace();
                    }                                           
                    break;    
            }                   
            inputindex++;
        }
        Afpopf1List.add(afpItem);               
        }           
    }
    else if (choiceNum == 2) {

    }
}     

}

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I think setDataList() and setDataList() are not good methods. When I implement a program in java, the setDataList() method only map to Afpopf1, and I write case to map each variable of DB table.It isn't effective code and stupid. Then, if a 4gl program has a new table variable, I must write another method for that table to receive the data.

I don't think that is a good idea, so I want to know how to improve the java code, or tell me the correct way to implement the function in java. I haven't touched Java EE before.

If the solution is about Java EE, I hope the answer is in detail or includes some example code.

Answer 1

You'll probably be disappointed, but this is how it's actually done, for example using Spring JDBC template: every SQL query has hand-coded mapping into an appropriate bean object.

If you want it done automatically, you should consider using an ORM such as Hibernate instead of the raw JDBC.

Answer 2

See this:

http://www.codeproject.com/Tips/372152/Mapping-JDBC-ResultSet-to-Object-using-Annotations

You need to do Enity class for apply ResultSetMapper