Java Oracle: Storing a TreeMap as BLOB?

Question

I have the following code:

  public void StoreMapInDB(TreeMap<DateTime, Integer> map) throws
        IOException, FileNotFoundException{
    try {
  PreparedStatement insertMap = null;
  String insertString = "INSERT INTO TESTMAP(ID, NAME) VALUES (1, ?)";
  Connection con=null;
  con.setAutoCommit(false);
  Class.forName("oracle.jdbc.driver.OracleDriver");
  con=DriverManager.getConnection(
    "jdbc:oracle:thin:@XXXXX",
    "XXX",
    "XXX");
    //This line is incorrect for sure 
    //insertMap.setBlob(1, map.);
    } catch(Exception e){e.printStackTrace();}
}

The connection works and all with database. This time i am trying to insert the map ie the treemap i created into a column in the table with type BLOB. How can I do that? is there any other better datatypes that I should look into?

Thanks,

Answer 1

If you want to put your object into BLOB datatype, You could do something like this:

// Serialize to a byte array
ByteArrayOutputStream bos = new ByteArrayOutputStream() ;
out = new ObjectOutputStream(bos) ;
out.writeObject(object);
out.close();

// Get the bytes of the serialized object
byte[] buf = bos.toByteArray();
PreparedStatement prepareStatement = connection.prepareStatement("insert into tableName values(?,?)");
prepareStatement.setLong(1, id);
prepareStatement.setBinaryStream(2, new ByteArrayInputStream(buf), buf.length);

Answer 2

There are two ways you can go about this...

• You can take advantage of the fact that the collections are serializable and output them to a byte array, as shown in the answer to this question .

• You could change the type of your table so that instead of using a binary field to store a specific implementation of a TreeMap, you store the keys and values as individual rows that can then be extracted and used to rebuild the map later. This option is more future-proof because you won't rely on TreeMap and its serialization format forever. Instead of using the columns (id, data) , you would use (id, key, value) . To save to the DB, you iterate over the Map's entrySet() and insert each key/value pair using the same row ID.