when to use the abstract factory pattern?

Posted by hguser on Stack Overflow See other posts from Stack Overflow or by hguser
Published on 2010-04-23T12:24:25Z Indexed on 2010/04/23 21:43 UTC
Read the original article Hit count: 382

Filed under:
|
|

Hi: I want to know when we need to use the abstract factory pattern.

Here is an example,I want to know if it is necessary.

The UML

THe above is the abstract factory pattern, it is recommended by my classmate. THe following is myown implemention. I do not think it is necessary to use the pattern.

And the following is some core codes:

    package net;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;



public class Test {
    public static void main(String[] args) throws IOException, InstantiationException, IllegalAccessException, ClassNotFoundException {
        DaoRepository dr=new DaoRepository();
        AbstractDao dao=dr.findDao("sql");
        dao.insert();
    }
}

class DaoRepository {
    Map<String, AbstractDao> daoMap=new HashMap<String, AbstractDao>();
    public DaoRepository () throws IOException, InstantiationException, IllegalAccessException, ClassNotFoundException  {
        Properties p=new Properties();
        p.load(DaoRepository.class.getResourceAsStream("Test.properties"));
        initDaos(p);
    }
    public void initDaos(Properties p) throws InstantiationException, IllegalAccessException, ClassNotFoundException {
        String[] daoarray=p.getProperty("dao").split(",");
        for(String dao:daoarray) {
            AbstractDao ad=(AbstractDao)Class.forName(dao).newInstance();
            daoMap.put(ad.getID(),ad);
        }
    }
    public AbstractDao findDao(String id) {return daoMap.get(id);}

}
abstract class AbstractDao {
    public abstract String getID();
    public abstract void insert();
    public abstract void update();
}
class SqlDao extends AbstractDao {
    public SqlDao() {}
    public String getID() {return "sql";}
    public void insert() {System.out.println("sql insert");}
    public void update() {System.out.println("sql update");}
}
class AccessDao extends AbstractDao {
    public AccessDao() {}
    public String getID() {return "access";}
    public void insert() {System.out.println("access insert");}
    public void update() {System.out.println("access update");}
}

And the content of the Test.properties is just one line:

dao=net.SqlDao,net.SqlDao

So any ont can tell me if this suitation is necessary?


© Stack Overflow or respective owner

Related posts about java

Related posts about Patterns