DAO +understanding/explanation

Well I gave you the simple explanation first but you wanted something more complcated so I gave you the link. Can't do more than that.

DAO is not a special way of doing a thing. Its a natural way to do it in OO. I can't think of any other way to design software that uses a datastore of some sort without a DAO layer.

_dnoyeBa at 2007-7-14 1:21:21 >

Here is an example.

This is from one of my DAOs

class DBGraphic extends DBObject {

void setLocation(Point p) throws DatasourceException {

try {

String qstring = "UPDATE containableGraphics SET " + "X = " + p.x + "," + "Y = " + p.y + " " + "WHERE ID = " + getID() + " ;";

int records = getDatabase().executeUpdate(qstring);

if(records == 0){

throw new DatasourceException("Failed to update location");

}

assert records < 2 :"Improper number of records updated";

}

catch (SQLException sqle) {

throw new DatasourceException(sqle);

}

}

}

And this is from one of my business objects that uses it sorta

class WADBaseModel implements IBaseModel {

public final void setLocation(Point p) throws WADException{

checkDisposed();

checkDeleted();

if (!this.location.equals(p)){

try {

this.graphic.setLocation(p);

this.location = new Point(p);

firePhysicalPropertyChange(ModelProperties.LOCATION, new Point(p));

}

catch (DatasourceException e) {

throw new WADException("Unable to modify dao",e);

}

}

}

}

_dnoyeBa at 2007-7-14 1:21:21 >