自己实现的依赖注入小玩具

package app10e.util;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.mchange.v2.c3p0.DataSources;

import app10d.action.GetProductsAction;
import app10d.action.SaveProductAction;
import app10d.dao.ProductDAO;
import app10d.dao.ProductDAOImpl;
import app10d.validator.ProductValidator;

public class DependencyInjector {
  private DataSource dataSource;

  public void start()
  {
      //使用C3P0连接池
      ComboPooledDataSource cpds=new ComboPooledDataSource();
      try
      {
          cpds.setDriverClass("com.mysql.jdbc.Driver");
      }
      catch(Exception e)
      {
          e.printStackTrace();
      }

      cpds.setJdbcUrl("jdbc:mysql://localhost:3306/test");
      cpds.setUser("root");
      cpds.setPassword("123");

      cpds.setMinPoolSize(5);
      cpds.setAcquireIncrement(5);
      cpds.setMaxPoolSize(20);
      dataSource=cpds;
  }

  public void shutDown()
  {
      try
      {
          DataSources.destroy(dataSource);
      }
      catch(Exception e)
      {
          e.printStackTrace();
      }
  }

  public Object getObject(Class type)
  {
      if(type==ProductValidator.class)
      {
          return new ProductValidator();
      }
      else if(type==ProductDAO.class)
      {
        return createProductDAO();
      }
      else if(type==GetProductsAction.class)
      {
          return  createGetProductAction();
      }
      else if(type==SaveProductAction.class)
      {
          return createSaveProductAction();
      }
      return null;
  }

      private GetProductsAction createGetProductAction()
      {
          GetProductsAction getProductsAction=new GetProductsAction();
          getProductsAction.setProductDAO(createProductDAO());
          return getProductsAction;
      }

      private SaveProductAction createSaveProductAction()
      {
          SaveProductAction saveProductAction=new SaveProductAction();
          saveProductAction.setProductDAO(createProductDAO());
          return saveProductAction;
      }

      private ProductDAO createProductDAO()
      {
          ProductDAO productDAO=new ProductDAOImpl();
          productDAO.setDataSource(dataSource);
          return productDAO;

      }

  }