java - Better Design for multiple data retrieval -

i inherited code decorator pattern used retrieve data multiple data sources. flow of code initial datagetter created , other datagetters encapsulate retrieve more data other sources. kind of looks this:

datagettera gettera = new datagettera(); datagetterb getterb = new datagetterb(gettera); datagetterc getterc = new datagetterc(getterb); map data = getterc.getdata(); 

each datagetter retrieves data different table , combines data 1 map.

i wondering there better design this?

1. you define interface load data map.

   public interface dataloader {

   void loaddata(map map); 

   }

2. implement interface different data sources

   public class a_dataloader implements dataloader {

   public void loaddata(java.util.map map) {      // load data data source map } 

   }

   public class b_dataloader implements dataloader {

   public void loaddata(java.util.map map) {      // load data data source b map } 

   }

   public class c_dataloader implements dataloader {

   public void loaddata(java.util.map map) {      // load data data source c map } 

   }

3. load data

   public static void main(string[] args) {

   map map = new hashmap();  // load data data source dataloader loader = new a_dataloader(); loader.loaddata(map);  // load data data source b loader = new b_dataloader(); loader.loaddata(map);  // load data data source c loader = new c_dataloader(); loader.loaddata(map); 

   }

4. you may have xml/database configuration define list of dataloader implementation used. if use ioc container such spring ioc or cdi. easy instance of dataloader implementation.