public interface IDBQuery {
   String request();
 }

public class DBQuery implements IDBQuery {
  public DBQuery(){
    try {
      Thread.sleep(10000);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  public String request() {
    return "string request";
  }
}

public class IDBQueryProxy implements IDBQuery {
  private DBQuery dbquery; 
  public String request() {
    if(dbquery==null)
      dbquery = new DBQuery();
    return dbquery.request();
  }
}

public class ProxyText {
  public static void main(String[] args) {
    IDBQuery dbquery = new IDBQueryProxy();
    System.out.println(dbquery.request()); 
  }
}

public interface IDBQuery {
   String request();
 }

public class JdbDbqueryHandler implements InvocationHandler{
  IDBQuery idbquery = null;
  @Override
  public Object invoke(Object proxy, Method method, Object[] args)
      throws Throwable {
    if(idbquery==null){
      idbquery = new DBQuery();
    }
    return idbquery.request();
  }
  public static IDBQuery createJdbProxy(){
    IDBQuery jdkProxy = (IDBQuery) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(),
        new Class[]{IDBQuery.class}, new JdbDbqueryHandler());
    System.out.println("JdbDbqueryHandler.createJdbProxy()");
    return jdkProxy;
  }

}

public class ProxyText {
  public static void main(String[] args) {
    IDBQuery idbQuery = JdbDbqueryHandler.createJdbProxy();
    System.out.println(idbQuery.request());
  }
}