I have seen two ways of implementing DAO-DVO design.
1) DVO are objects and DAOs are instantiated using factories i.e DAOs are also objects
2) DVOs are again objects but in this case, ... |
I'm trying to write an embedded (NOT web, not enterprise) content management system in Java, with a focus on organization and ease of use and scalability to 100,000 or so items. ... |
Can anyone point me to a well written DAO using JDBC, that covers all the exceptions a DAO should handle.
I looked at some samples at java.sun.com, their blue prints but there ... |
I often need to implement DAO's for some reference data that doesn't change very often. I sometimes cache this in collection field on the DAO - so that it is only ... |
How are DAOs usually designed for the typical business application ? Does one class or pattern dialogue with the data source or do you simply have a separate DAO for each ... |
I have taken over some code that has been using the Firestorm DAO code generator from CodeFutures. I believe that the license for this is going to be up ... |
we have been trying to benchmark our application performance in multiple way for sometime now.
I always believed that object creation in java using Class.newInstance() was not slow (at least after ... |
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I'm developing a medium Java app, and i'm facing a small problem due to my lack of experience.
I've a custom DAO, which gets "Article" objects from the Database. I've the Article ... |
I'm currently creating an EJB3 Data Access Class to handle all database operations in my Java EE 6-application. Now, since Java EE 6 provides the new ApplicationScoped-Annotation, I wonder what state ... |
I'd like to write to my Oracle DB the user ID and IP address of the logged in user (web app) whenever I perform SQL UPDATEs and INSERTs. Such as
public static ...
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The usual advice is to close JDBC ressources once they're no longer needed. This could be done in a catch and finally. However, what if a DAO method only manipulates one ... |
I need an advice w.r.t. one of the design approach we are considering.
We are implementing a Java web service provider which acts on data in relational database. Our propose classes ... |
I have a DAO class with many methods that have a lot of repeated code along the lines of: -
public void method1(...) {
Connection conn = null;
try {
...
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I'm unsure of how I could write a DAO to write information to XML files. I know how to use Sax and JDOM but what I'd like to know is how ... |
I have a question related to correct handling of returns of the DAO library I'm writing for one project. This library probably is going to be used by another people and ... |
Working on a business application using MVC structure and a Business Object / DAO pair architecture. For any normal business object, the CRUD functions are fairly straightforward. But what's ... |
Is it an acceptable practise to use a DAO pattern to access CSV files?
I'm asking because I'd usually have a utility method to read a CSV. Having a DAO would sort ... |
At my work place, we use DAO pattern to hancle any sort of database operation. It hides bulky statements from programmer. Programmers need to write sql query and logic to handle ... |
I'm searching for free and simple DAO generator for java (it needs to create entities/bens from db tables/views and generate basic CRUD code). Currently, I`m using DAO4J which lacks some functionality ... |
I want to access my applicant database that's why I created a DAO class for it.
I think I have lots of code smells because I keep on repeating some code. So ... |
i want to implement a sales aand inventory management system, am confused ... |
What should be the best way to design a DAO class ?
Approach#1: Design DAO class as an object.
class Customer {
//customer class
}
class CustomerDAO {
public void saveCustomer(Customer customer) {
//code
...
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I would like build up a dummy dao class with help of List where the Advert is entity class, but when I try to create an instance with this code:
public AdvertDaoImpl() ...
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org.springframework.dao.TransientDataAccessResourceException: PreparedStatementCallback; SQL [ select id from employeerole where username = kiran and pin is NULL]; The index 1 is out of range.; nested exception is com.microsoft.sqlserver.jdbc.SQLServerException: The index 1 is ...
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I was trying to write a user authentication system in Java. So I wrote some DAO class. First I did write a class named Persistence which is abstract. It is responsible ... |
I have a doubt considering changing this :
List<String> elements = new ArrayList<String>();
elements = elementDao.findElementsById(elementId);
to
List<String> elements;
elements = elementDao.findElementsById(elementId);
(I'm using DAO with Hibernate)
Can this cause any errors or exceptions (the fact ... |
I'm currently in the process of creating a data access layer for an application. This application will initially connect to an Oracle database but will later also connect to a DB2 ... |
I tried out DAO Pattern after reading
http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html
but I get NullPointerException when I run the servlet
DAOFactory
package dao;
import java.sql.SQLException;
public abstract class DAOFactory {
// List of DAO types supported by the ...
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I have a few Objects that are related as such: A Document has one WorkflowInstance and each WorkflowInstance has many WorkflowInstanceDetails
public class Document implements Serializable {
private static final long ...
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Suppose I have the following DAO interface:
public interface CountryData {
/**
* Get All Countries.
*
...
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I have an architecture that looks like this:
(client: android, server: web services axis2)
Presentation layer (Android activities and controllers):
LoginActivity.java
WebServices Layer:
Services.java
Domain Layer:
...
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Hi, I have added a new domain class to my existing grails project. When I click on link I am getting below error message. Error 500: org.springframework.dao.InvalidDataAccessResourceU sgaeException: could not execute ... |
hi all: if DAO factory frame work is used in a multi- threaded J2EE project, when is it appropriate to cach a single object and return it over and over again, vs. retruning a brand new object. for example: //cached object public class DAOFactory { privte EmployeeDAO MyEmployeeDAO = new EmplyeeDAO(); public EmplyeeDAO getEmplyeeDAO(); { return MyEmployeeDAO;} } vs. //new object ... |
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Let's say I have a business object with the following structure: class BusObj { BusObj2 busObjChild; } Is it considered bad design to do this: class BusObjDAO { public BusObj getBusObj(long id) { BusObj busObj = new BusObj(); //establish connection BusObj2DAO busObj2DAO = new BusObj2DAO(); BusObj2 busObj2 = BusObj2DAO.getBusObj2(id, connection); return busObj; } } or should I have some kind of ... |
Hi all, I am in fond of learning DAO and trying to implement it in my project. I don't know where to start. Before that I'll just brief my expertise level. I know Core Java and I had done 4 to 5 projects in JSP and Servlets. If I want to learn DAO, what are the things I have to learn ... |
hi guys this question is actually about MSSQL but I wasn't sure where to post it I have a stored procedure in which I need to get all the classes which are taking place in a particular month for eg If I pass August 2006 it should get me all the classes which for eg start and end at these dates ... |
Originally posted by Puthriah Sarma: Is it OK to have instance variables in DAOs? Is my current design efficient? Appreciate expert opinion and thanks in advance. It totally depends !! It depends on how you are organising your code.I will not prefer to use any variable as instance variable, which deals with database. Using connection,statement or resultset as instance variable means ... |
Howdy fellow Java software engineers, This is not really a question concerning some kind of problem, but this is mainly an attempt to explore opinions and views regarding best practices. Currently I'm working on a project in which I have choosen to implement the DAO design pattern, including a DAO Abstract Factory to facilitate the opportunity for datasource replacement (which, for ... |
Hello ranch members, I have the following scenario and would like suggestions on the best possible design for it. TableA (id_A, blah1, blah2) TableB (id_B, id_A) I am using MySQL and id_A and id_B are primary keys for the respective tables. I am generating values for keys using AUTO_INCREMENT in MySQL. I have a single DAO class and want to insert ... |
Hi everyone hows it going? We have an application that generates dynamic reports. It could also generate different report templates. For every type of report, there are sections, for every section there are items, for every times there are sub-items and other fields. So a create/update report template method in our business object class looks like this: public void createReportTemplate(ReportData data){ ... |
Hi, I have a small SWING based desktop application and I am looking for some persistence framework which is kind of small. I found this open source framework sequalite.sourceforge.net while doing a google search. Looks quite straight forward. Anybody used the sequalite DAO framework? Looks very tiny not sure how good is it? Please share your experiences. thanks, Supriya |
Hi. I'm trying to build a simple login page and registration page. People login through the login page. I use a DAO Factory to check the database to see if their username and password is in there. I'm having problems setting up the httpsession. I had it working with the Httpsession but now I have problems. I also want the person ... |
We recently started using the DAO pattern to create classes used to retreive data from Oracle. We have a DAOFactory which is called to get a particular DAO class, which is really just an interface for an ORImpl class that accesses the database and gets the data. We created all of the ORImpl classes as singletons, with the private constructor, static ... |
Hi. In my application, I have domain objects like : Book, Author, Publisher (I'm using Hibernate).... I created interfaces like BookDAO, AuthorDAO and then implement them using HibernateDaoSupport. But while I'm coding my DAO's, a question came into my mind : Is it good to many DAOs (like my case) or to create a master DAO called for example : BookStoreDAO ... |
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If you elaborate the question more clearly, you would likely generate more useful response. Your last sentence "I want to know upon calling a DAO interface from the servlets (Correct me if i am wrong) how the DAO implementation class would be get called upon ? " is a bit too vague. Af far this sounds like that you wanted to ... |
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Hello all Members, In my application, Can i Write all query related stuff in Separate DAO class ? Can I make Separate DAO class for each table in Database ? Can I write one separate method for a each query that i fired in my program? Can you tell me In this way, professional development occur? Please guide me in this ... |
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please can somebody help me with my code...I want to develop a web app...that uses dao to encapsulate all the methods and connections so that the all calls are to to dao and not to database....so far its been okay but when I tried to make it into a singleton object, it threw errors ..precisely 3 errors...I want to know why...and ... |
Hi Guys I'm busy working on a simple two-tier app - Swing on the front-end and a JavaDB database on the back-end. I have designed it to use DTO and DAO classes for each table in the database. Since the app isn't designed to work with thousands of records at a time, I want to load all data in a table ... |
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Assume that we have methods such as insert , update , select and delete inside my DAO class . So please tell me if i make this DAO class as Singleton . In my opinion this saves a lot of memory .please guide . But as per my knowledge as DAO methods contains reference to connection object , so there would ... |
Hello all! Dear Members my question is related to Software-engineering approach about DAO (Data Access Object) in three tier architecture. Am a student and as for the final project of my course I had to develop a three tier web based application.. the approach I choose for my project was I divided my classes into three layers as required by the ... |
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61. DAO forums.oracle.comHi all I am building a small application using strurs1.2.9 , netbeans 5.5.1 and postgresql as my data base. I am using DAO for my database connection . I have written all the dao class files and when i try to run it gives a error NullPointerException. When the same code is run on the different machine it is running fine. ... |
62. DAO's forums.oracle.com |
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Im not sure its the right topic to post it but Ill try I have to create a relatively simple app that manages personnel reviews and has very simple structure already implemented in legacy DB. Person Review N:N Person Person Review - N:1 Various Review Choices/enumerations (tech skills, lead skills, etc) Im having doubts on implementing DAOs and ... |
public void insertPromo(Promo promo) { //promoInsert.insertDetails(promo, getNextId("x_promo_ui")); promoInsert.insertDetails(promo); } private class PromoInsert extends SqlUpdate { public PromoInsert() { super(getDataSource(), SQL_INSERT_PROMO_DETAIL); declareParameter(new SqlParameter("x_promo_ui.x_bus_org", Types{color:#ff0000}.INTEGER)); {color:#000000}*// but in my DB this field is defined as NUMBER but thrs no Types.NUMBER available.* declareParameter(new SqlParameter("x_promo_ui.x_promo_name", Types.VARCHAR)); declareParameter(new SqlParameter("x_promo_ui.x_promo_desc", Types.VARCHAR)); declareParameter(new SqlParameter("x_promo_ui.x_promo_reqd_flag", Types.VARCHAR)); declareParameter(new SqlParameter("x_promo_ui.x_promo_channel", Types.VARCHAR)); declareParameter(new SqlParameter("x_promo_ui.x_promo_benefit", Types.VARCHAR)); compile(); } public int insertDetails(Promo promo) throws ... |
Hi I came across an design pattern where they call the DAO from Session facade. The purpose of session facade is to minimise the number of network calls. Even though there are no network calls involved why do they go for session facade to call the DAO. Wont a DAOFActory will help them doin this. Even if the requirement is to ... |
68. DAO??? forums.oracle.com |
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hi everybody! i have a problem in my application design .... I use DAO-Pattern to access objects which are persisted. my DAOs offers some common CRUD-operations. the bussiness-logic (session-handling, transaction-logic) is enculapsed in command-pattern. for the reason that the session-handling and transaction-logic depends on the underlying DAO implementation (transaction-handling hibernate is different to jdbc) there is a implementation dependency between DAOs ... |
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Well, you're naming them as OracleDatasources so they're not portable accross different databases. Secondly you're configuring the connections in code. A better way would have a connection pool set up, so you could configure it with an xml file/property file, ask the connection pool for a data source and use that. It would eliminate your database specific code as well. But ... |
75. DAO use forums.oracle.comwhat is the use of DAO classes in web based applications Here's my take on it - DAO or Data Access Object is basically a class that acts as an itemidiary between 2 different parts of a program. This way neither side has to worry about who they are dealing with. Think of a mortgage broker as a DAO. They worry ... |
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What is the best approach to passing a large set of data from Class A to Class B? I have a DAO Class that connects to a database to retrieve data. I tried saving the data in a collection (map) and passing the collection to Class B. The problem here is that the data is may be too large for a ... |