java qr code reader app The Java Persistence API in Java

Maker QR Code JIS X 0510 in Java The Java Persistence API

The Java Persistence API
Denso QR Bar Code Generation In Java
Using Barcode generator for Java Control to generate, create Denso QR Bar Code image in Java applications.
www.OnBarcode.com
QR Code JIS X 0510 Recognizer In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
You ve now seen the most important strategies and some optional ones for interacting with objects in a Hibernate application and what methods and operations are available on a Hibernate Session. If you plan to work only with Hibernate APIs, you can skip the next section and go directly to the next chapter and read about transactions. If you want to work on your objects with Java Persistence and/or EJB 3.0 components, read on.
UPC-A Supplement 2 Maker In Java
Using Barcode generator for Java Control to generate, create GS1 - 12 image in Java applications.
www.OnBarcode.com
Barcode Encoder In Java
Using Barcode encoder for Java Control to generate, create Barcode image in Java applications.
www.OnBarcode.com
The Java Persistence API
ANSI/AIM Code 39 Maker In Java
Using Barcode generation for Java Control to generate, create ANSI/AIM Code 39 image in Java applications.
www.OnBarcode.com
PDF417 Maker In Java
Using Barcode printer for Java Control to generate, create PDF-417 2d barcode image in Java applications.
www.OnBarcode.com
We now store and load objects with the Java Persistence API. This is the API you use either in a Java SE application or with EJB 3.0 components, as a vendor-independent alternative to the Hibernate native interfaces. You ve read the first sections of this chapter and know the object states defined by JPA and how they re related to Hibernate s. Because the two are similar, the first part of this chapter applies no matter what API you ll choose. It follows that the way you interact with your objects, and how you manipulate the database, are also similar. So, we also assume that you have learned the Hibernate interfaces in the previous section (you also miss all the illustrations if you skip the previous section; we won t repeat them here). This is important for another reason: JPA provides a subset of functionality of the superset of Hibernate native APIs. In other words, there are good reasons to fall back to native Hibernate interfaces whenever you need to. You can expect that the majority of the functionality you ll need in an application is covered by the standard, and that this is rarely necessary. As in Hibernate, you store and load objects with JPA by manipulating the current state of an object. And, just as in Hibernate, you do this in a unit of work, a set of operations considered to be atomic. (We still haven t covered enough ground to explain all about transactions, but we will soon.) To begin a unit of work in a Java Persistence application, you need to get an EntityManager (the equivalent to the Hibernate Session). However, where you open a Session from a SessionFactory in a Hibernate application, a Java Persistence application can be written with managed and unmanaged units of work. Let s keep this simple, and assume that you first want to write a JPA application that doesn t benefit from EJB 3.0 components in a managed environment.
Generate QR Code ISO/IEC18004 In Java
Using Barcode encoder for Java Control to generate, create QR Code image in Java applications.
www.OnBarcode.com
Industrial 2 Of 5 Maker In Java
Using Barcode creator for Java Control to generate, create Code 2 of 5 image in Java applications.
www.OnBarcode.com
Storing and loading objects
Painting QR Code 2d Barcode In Java
Using Barcode drawer for Java Control to generate, create QR Code image in Java applications.
www.OnBarcode.com
QR Creator In VS .NET
Using Barcode generation for Visual Studio .NET Control to generate, create QR Code image in .NET applications.
www.OnBarcode.com
The term unmanaged refers to the possibility to create a persistence layer with Java Persistence that runs and works without any special runtime environment. You can use JPA without an application server, outside of any runtime container, in a
Scanning UPC-A Supplement 2 In VS .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
QR Code ISO/IEC18004 Creation In Java
Using Barcode encoder for Android Control to generate, create Quick Response Code image in Android applications.
www.OnBarcode.com
Working with objects
Matrix Drawer In VS .NET
Using Barcode generator for ASP.NET Control to generate, create 2D image in ASP.NET applications.
www.OnBarcode.com
Denso QR Bar Code Creator In Visual C#
Using Barcode generator for .NET framework Control to generate, create QR-Code image in Visual Studio .NET applications.
www.OnBarcode.com
plain Java SE application. This can be a servlet application (the web container doesn t provide anything you d need for persistence) or a simple main() method. Another common case is local persistence for desktop applications, or persistence for two-tiered systems, where a desktop application accesses a remote database tier (although there is no good reason why you can t use a lightweight modular application server with EJB 3.0 support in such a scenario). Beginning a unit of work in Java SE In any case, because you don t have a container that could provide an EntityManager for you, you need to create one manually. The equivalent of the Hibernate SessionFactory is the JPA EntityManagerFactory:
EAN 13 Drawer In None
Using Barcode generator for Office Word Control to generate, create GTIN - 13 image in Office Word applications.
www.OnBarcode.com
Drawing Barcode In Objective-C
Using Barcode maker for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
EntityManagerFactory emf = Persistence.createEntityManagerFactory("caveatemptorDatabase"); EntityManager em = emf.createEntityManager(); EntityTransaction tx = em.getTransaction(); tx.begin();
UPC Symbol Creator In VS .NET
Using Barcode printer for .NET framework Control to generate, create UPCA image in Visual Studio .NET applications.
www.OnBarcode.com
UPC Symbol Printer In None
Using Barcode maker for Software Control to generate, create UPC-A Supplement 5 image in Software applications.
www.OnBarcode.com
The first line of code is part of your system configuration. You should create one EntityManagerFactory for each persistence unit you deploy in a Java Persistence application. We covered this already in chapter 2, section 2.2.2, Using Hibernate EntityManager, so we won t repeat it here. The next three lines are equivalent to how you d begin a unit of work in a stand-alone Hibernate application: First, an EntityManager is created, and then a transaction is started. To familiarize yourself with EJB 3.0 jargon, you can call this EntityManager application-managed. The transaction you started here also has a special description: It s a resource-local transaction. You re controlling the resources involved (the database in this case) directly in your application code; no runtime container takes care of this for you. The EntityManager has a fresh persistence context assigned when it s created. In this context, you store and load objects. Making an entity instance persistent An entity class is the same as one of your Hibernate persistent classes. Of course, you d usually prefer annotations to map your entity classes, as a replacement of Hibernate XML mapping files. After all, the (primary) reason you re using Java Persistence is the benefit of standardized interfaces and mappings. Let s create a new instance of an entity and bring it from transient into persistent state:
EAN-13 Decoder In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Decode Code 128C In Visual C#
Using Barcode reader for VS .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Item item = new Item(); item.setName("Playstation3 incl. all accessories"); item.setEndDate( ... );
Copyright © OnBarcode.com . All rights reserved.