Introduction 2. Install the different components 3. Set Weblogic to deploy "exploded archives" 4. Add a servlet, run the project 4. Add a stateless session bean EJB 4.
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Introduction 2. Install the different components 3. Set Weblogic to deploy "exploded archives" 4. Add a servlet, run the project 4. Add a stateless session bean EJB 4. Call the session bean from the servlet 5. Configure the persistence. Add a JPA entity class mapped to the Manufacturer table of the sample database 5. Write a stateless session bean facade for this entity class 5. Let's the servlet use the session bean facade 6. Implements the rest of the CRUD operations 7.
Add several methods to the ManufacturerFacade. Adapt the JSP so that you can remove, add or search a manufacturer 9. Create an injectableBeans package, add a TextDecorator interface 9. Add a beans that implements the TextDecorator interface, names BoldMaker 9.
Inject the bean in the Servlet, test the project 9. Add a second injectable bean for decorating Strings in italic 9. Create two qualifier annotations, qualify the beans, qualify the injection Using interceptors Add an interceptor binding type annotation to the project named Logging Update the beans. Annotated the ManufacturerFacade for logging, run the project. Du to a weblogic 12c bug, project with the "web profile" raise some unexpected errors in the persistence context when the project properties are not set to "deploy as exploded archives" see.
Create a standard dynamic web project using Eclipse, call it for example "Exo1WebProfile". Click twice on the next button and in the last screen, check "Generate web. Add a Servlet in the project, call it TestServlet, and add it in a package named "servlets". Click finish. Add some lines in the doGet method, like these:. Then modify the web. The first time you will be asked to choose a server.
Select "weblogic 12c", check the checkbox so that thos will be a default value for this project and click finish. This should launch weblogic, the console tab should appear, etc. And after a while you should see a browser inside Eclipse showing "Welcome to Exo1 test servlet!
Now we will add a stateless session bean EJB to the project. Select as the type of element to add to the project "session bean EJB 3. For the moment leave everything with default values stateless, no interface. Notice the Stateless and LocalBean that indicates that we have a stateless session bean that can be only called from the same JVM. Remote session beans are not allowed in a web profile project. Then run the project. You do not now if a "new" has been performed or if an existing instance has been used or if there are more than one instance running in the web server.
Check that you added the database both in Eclipse and in Weblogic. Look at your project, a persistence. This file is used for configuring the different persistence units that you will use in your project.
A persistence unit is an object you will use from your code that works with a given database, using an Object Relational Mapping tool like Hibernate, Eclipse Link, Toplink, etc. This file also is useful for specifying if you are allowed to create tables, alter or delete tables, etc. As you may see it says that we are going to work woth eclipseLink provider node Double click on the persistence.
We are going to configure the database connection, so click on the connection tab at the bottom of the designer. We are using a remote database through a connection pool open on the we logic server. Ok, you are done with persistence. Let's add an entity class generated from the Manufacturer table of the sample database If asked to what project you want to add the entity, select the current project.
Click next. Then you are asked to choose the connection and table. On the last screen you may change the name of the class but it is better to leave the proposed name "Manufacturer" unchanged. Click finished. Look at your project, under the "entities" package you should have a Manufacturer. Usually, one best practice consists in associating a "facade" with each entity class.
These are projects that use JSF and some special faces libraries from Oracle. They will not be studied during this training. So let's add a stateless session facade for Manufacturers to this project. Add a new stateless session bean, put it in the "sessions" package, name it ManufacturerFacade. Add in that bean an EntityManager so that we will be able to "talk" to the database and do other interesting things.
Just add these two lines as class attributes:. Your session facade should look like that:. Notice that executing this request does not return tuples but a Collection of Objects in our case a List of instances of Manufacturer. Let's ass this on the Servlet, as well as a call to the getManufacturers method.
The trick consists in a adding to the request the data to be displayed before forwarding the request to the JSP:. In order to display the manufacturers' properties we use the EL expression langage. Defines a loop on a collection named "manufacturers". This collection will be searched in different scopes: the page, the request, the session, the context, etc. As in the servlet we put an attribute named "manufacturers" in the request, it is the one that will be found.
We will now add some methods to the facade in order to be able to create new manufacturers, remove an existing manufacturer or look for a manufacturer In that example we added some "classic" methodes for a facade. We modified the Servlet a little so that depending on a HTTP parameter called "action", the servlet can do different operations. In that example we only added "add" and "remove" operations. Look at the code and try to understand the logic of the operations This will call the servlet with an action parameter equals to "add", indicating that we want to add a new manufacturer to the database.
The rest of the parameters describe the manufacturer we want to add. Normally, this line should add one new Manufacturer and dipslay an updated list. If you try to remove other manufacturers using their IDs, you may encounter some exceptions as some of the manufacturers primary keys have a relationships to some foreign keys in other tables.
Typical error: "Internal Exception: java. Error Code: -1".. Let's add a form at the beginning of the page, and a link for removing a manufacturer directly in the table. The add and remove and count have been implemented in the servlet but the Search by Name or Remove by name did not have been implemented. You may try this code, then complete the implementation. Notice also that we did not use any kind of pagination here, whereas the method findByRange exists in the facade.
We propose here to the Context Dependency Injection feature of Java EE6 by creating some injectable beans for decorating the list of manufacturers. This file can be empty, this will be enough for enabling CDI, but a more "standard" version is preferable, as we will add things to it later on If you get null pointers exceptions in your project, maybe you forgot to add this beans.
In a package named "injectableBeans", add a new interface named TextDecorator that looks like that:. The beans that will implement this method will all have a decorate method that takes a String as input and returns the same String but "decorated", for example, in bold or in italic This bean is just a plain Java class. However, when one creates a java bean, it is the same as having the Dependant annotation. For non-default " scopes such as ApplicationScope, SessionScope, etc.
Write a second bean similar to the BoldMaker. Call it ItalicMaker this time. The code should look like that:. Caused By
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