The first time I wrote an EJB summary!

I plan to learn EJB this month. I read the first three chapters and found it messy. It turns out that EJB is not so easy to learn. The first helloworld took 4 hours, but finally heard the sound of EJB. I will not talk about the specific process. I will mainly write down the mistakes that cainiao's friends may make, just like me. You are also welcome to give me some advice.

I use JBoss + eclipse.

There is nothing to say about JBoss installation, remember to add in the environment variables after installation: jboss_home = C:/jboss-4.0.2 (here is the path to your JBoss installation ), add % jboss_home %/bin to path.

The JBoss directory structure is helpful for beginners.
Bin: JBoss switch scripts
Client: Client libraries (jars) used for communication with JBoss)
Docs: Set the document sample. (For example, set the document sample in the information library)
Docs/DTD: Document Type Definitions (dtds) files for different XML files in JBoss.
Lib: When JBoss is started, libraries shared by different configurations will be read here.
Server: Stores different JBoss configuration files.
Server/Default: Configuration file preset by JBoss.
Server/default/Conf: JBoss configuration file.
Server/default/Data: JBoss database.
Server/default/deploy: JBoss Automatically releases the detection directory. (If ebj-jars, wars, and ears are released, JBoss automatically detects the directory)
Server/default/lib: When JBoss starts this configuration directory, it will read libraries.
Server/default/log: Stores JBoss log files.
Server/default/tmp: Stores JBoss files.
Server/default/work: Stores the compiled JAVA byte code of JBoss.

Note:
1: ejb-jar.xml is placed in the META-INF folder, if you want to build JBoss. XML is also put here.
2: If you run the client code and JBoss server on the same machine, the following code can be run without any modification,
Env. Put (context. provider_url, "localhost: 1099 ");
You can change the IP address on another machine.
3: If you encounter exceptions such as classnotfound during running, it means you have not imported the package. Just import it. I now run to import 2 packages, jnp-client.jar, jbossall-client.jar, they are in the client directory under JBoss.
4: I can see many pieces of JBoss. XML are written on the Internet. After I run it, I understand that it is used to set up JNDI. In fact, it is as simple as we do not need to set up JBoss. xml.
Remember: Object OBJ = CTX. Lookup ("hello"); here "hello" is your <EJB-Name> value in the ejb-jar.xml, If you create
If JBoss. XML is used, "hello" should be replaced with the value of <JNDI-Name>.

Here is my JBoss. xml:

<? XML version = "1.0" encoding = "UTF-8"?>
<! Doctype JBoss public "-// JBoss // DTD JBoss 4.0 // en" "jboss_4_0.dtd">
<JBoss>
<Enterprise-beans>
<Session>
<EJB-Name> Hello </EJB-Name>
<JNDI-Name> example/Hello </JNDI-Name>
</Session>
</Enterprise-beans>
</JBoss>

Helloclient. Java:

Package example;
Import javax. Naming. context;
Import javax. Naming. initialcontext;
Import javax. Naming. namingexception;

Import java. util .*;

Public class helloclient ...{

/***//**
* @ Param ARGs
*/
Public static void main (string [] ARGs )...{
// Todo auto-generated method stub
Hashtable Env = new hashtable ();

Env. Put (context. initial_context_factory, "org. jnp. Interfaces. namingcontextfactory ");
Env. Put (context. provider_url, "localhost: 1099 ");
Env. Put ("Java. Naming. Factory. url. pkgs", "org. JBoss. Naming: org. jnp. interfaces ");

Try ...{
Context CTX = new initialcontext (ENV );
Object OBJ = CTX. Lookup ("hello ");

Hellohome home = (hellohome) javax. RMI. portableremoteobject. Narrow (OBJ, hellohome. Class );
Hello = home. Create ();

System. Out. println (hello. hello ());

Hello. Remove ();
} Catch (exception e )...{
// Todo auto-generated Catch Block
E. printstacktrace ();
System. Out. println (E. getmessage ());
}
}

}

The above are some of my experiences and I hope to help beginners.