자바의 객체직렬화를 이용하면 직렬화된 객체를 파일, 데이터베이스 또는 원격으로 전송 하는 것이 가능 합니다.

물론 객체직렬화가 되기 위해선 Object는 자바의 Seriablizable 이라는 Interface를 구현해야 합니다. 그래서 이 Object는 Byte Stream 형태로 저장 되어 파일이나 DB에 저장 된 후 나중에 Load되어서 복원이 가능 하게 되는 것입니다.

아래의 예제는 ObjectSerTest 라는 클래스를 직렬화 가능하게 만든 후 오라클의 BLOB에  입력 한 후 읽어내는 예제 입니다.

=====================================================

SQL>conn scott/tiger
SQL> create sequence object_ser_seq increment by 1 start with 1;

주문번호가 생성되었습니다.

SQL> create table object_table (
  2  no number,
  3  obj_name varchar2(2000),
  4  obj_value blob default empty_blob()
  5  );

테이블이 생성되었습니다.

=================================================


/*
* Created on 2005. 2. 11
*
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
*/
package jdbc;

import java.io.*;
import java.sql.*;
import oracle.sql.*;

class ObjectSerTest implements java.io.Serializable{

  static final String driver_class = "oracle.jdbc.driver.OracleDriver";
  static final String connectionURL = "jdbc:oracle:thin:@localhost:1521:wink";
  static final String userID = "scott";
  static final String userPassword = "tiger";
  static final String getSequenceSQL = "SELECT object_ser_seq.nextval FROM dual";
  static final String writeObjSQL    = "BEGIN " +
                                       "  INSERT INTO object_table(no, obj_name, obj_value) " +
                                       "  VALUES (?, ?, empty_blob()) " +
                                       "  RETURN obj_value INTO ?; " +
                                       "END;";
  static final String readObjSQL     = "SELECT obj_value FROM object_table WHERE no = ?";

  /*
   ** +--------------------------------------------------+
   ** | METHOD: writeObj                                 |
   ** +--------------------------------------------------+
  */
  public static long writeObj(Connection conn, Object obj) throws Exception {

    long id = getNextSeqVal(conn);
    
    String className = obj.getClass().getName();
    CallableStatement stmt = conn.prepareCall(writeObjSQL);
    
    stmt.setLong(1, id);
    stmt.setString(2, className);    
    stmt.registerOutParameter(3, java.sql.Types.BLOB);
    stmt.executeUpdate();
    
    BLOB blob = (BLOB) stmt.getBlob(3);
    OutputStream os = blob.getBinaryOutputStream();
    ObjectOutputStream oop = new ObjectOutputStream(os);
    oop.writeObject(obj);
    oop.flush();
    oop.close();
    os.close();
    stmt.close();
    System.out.println("Done serializing: " + className);
    return id;

  } // END: writeObj


  /*
   ** +--------------------------------------------------+
   ** | METHOD: readObj                                  |
   ** +--------------------------------------------------+
  */
  public static Object readObj(Connection conn, long id) throws Exception {

    PreparedStatement stmt = conn.prepareStatement(readObjSQL);
    stmt.setLong(1, id);
    ResultSet rs = stmt.executeQuery();
    rs.next();
    InputStream is = rs.getBlob(1).getBinaryStream();
    ObjectInputStream oip = new ObjectInputStream(is);
    Object obj = oip.readObject();
    String className = obj.getClass().getName();
    oip.close();
    is.close();
    stmt.close();
    System.out.println("Done de-serializing: " + className);
    return obj;

  } // END: readObj

  /*
   ** +--------------------------------------------------+
   ** | METHOD: getNextSeqVal                            |
   ** +--------------------------------------------------+
  */
  private static long getNextSeqVal (Connection conn) throws SQLException {

    Statement stmt = conn.createStatement();
    ResultSet rs   = stmt.executeQuery(getSequenceSQL);
    rs.next();
    long id = rs.getLong(1);
    rs.close();
    stmt.close();
    return id;

  } // END: getNextSeqVal

  /*
   ** +--------------------------------------------------+
   ** | METHOD: main                                     |
   ** +--------------------------------------------------+
  */
  public static void main (String args[]) throws SQLException {

    Connection conn = null;
    Statement stmt = null;
    ResultSet rset = null;
    int insertResults;
    int deleteResults;

    try {
     
      System.out.print("\n");
      System.out.print("Loading JDBC Driver  -> " + driver_class + "\n");
      Class.forName (driver_class).newInstance();

      /*
      ** CONNECT TO THE DATABASE
      */
      System.out.print("Connecting to        -> " + connectionURL + "\n");
      conn = DriverManager.getConnection(connectionURL, userID, userPassword);
      System.out.print("Connected as         -> " + userID + "\n\n");

      /*
      ** TURN OFF AutoCommit
      */
      conn.setAutoCommit(false);

      ObjectSerTest obj = new ObjectSerTest();      

      long no = writeObj(conn, obj);
      conn.commit();

      System.out.print("Serialized OBJECT_ID => " + no + "\n\n");

      System.out.print("OBJECT VALUES  => " + readObj(conn, no) + "\n\n");
      conn.close();

    }  // TRY:

    catch (Exception e) {
      e.printStackTrace();
    }

    finally {
      if (conn != null) {
        try {
          System.out.print("Closing down all connections...\n\n");
          conn.close();
        }
        catch (SQLException e) {
          e.printStackTrace();
        }
      }
    } // FINALLY:

  } // METHOD: main

} // CLASS: ObjectSerTest



[결과]


Loading JDBC Driver  -> oracle.jdbc.driver.OracleDriver
Connecting to        -> jdbc:oracle:thin:@localhost:1521:wink
Connected as         -> scott

Done serializing: jdbc.ObjectSerTest
Serialized OBJECT_ID => 2

Done de-serializing: jdbc.ObjectSerTest
OBJECT VALUES  => jdbc.ObjectSerTest@601bb1

Closing down all connections...