Openejb :: container :: Core framework in the Java library
Openejb :: container :: Core framework in the Java library
OpenEjb is a powerful open source company JavaBeans (EJB) container framework, which provides a lightweight, flexible and scalable method to build and manage EJB applications.It uses the core components in the Java class library to make the development and deployment of EJB applications simpler and efficient.
This article will introduce the guidelines of OpenEjb's core framework in the Java class library, and provide some practical Java code examples to help readers better understand and apply OpenEjb.
1. Introduce OpenEjb dependencies
To use the core framework of OpenEjb in the Java library, we need to add OpenEjb's dependencies to the project construction file.You can use Maven or Gradle and other construction tools to add the following dependencies:
<dependency>
<groupId>org.apache.openejb</groupId>
<artifactId>openejb-core</artifactId>
<version>4.7.4</version>
</dependency>
2. Create EJB
Now, you can start creating and defining EJB components.You can use@stateless,@stateful or @SINGLETON and other annotations to mark the class, and use @EJB annotations to inject other EJB components.
@Stateless
public class MyBean {
@EJB
private AnotherBean anotherBean;
public void doSomething() {
// Call the injected Anotherbean method
anotherBean.anotherMethod();
}
}
@Stateless
public class AnotherBean {
public void anotherMethod() {
// Implement specific logic
}
}
When using OpenEjb's core framework, you need to create an OpenEjb initialization configuration file to specify the deployment and configuration information of the EJB component.The example of the configuration file is as follows:
<?xml version="1.0" encoding="UTF-8"?>
<openejb>
<Resource id="MyDataSource" type="DataSource">
JdbcDriver com.mysql.jdbc.Driver
JdbcUrl jdbc:mysql://localhost:3306/mydatabase
UserName myuser
Password mypassword
</Resource>
<Resource id="MyQueue" type="javax.jms.Queue"/>
<Bean id="MyBean" class="com.example.MyBean">
AnotherBean anotherBean
</Bean>
<Bean id="AnotherBean" class="com.example.AnotherBean"/>
</openejb>
The configuration file can define data sources, JMS queues, and EJB components, and use the corresponding label to specify the ID, type, and attributes of the specified resource.
4. Start OpenEjb container
When using the core framework of OpenEjb in the Java library, you need to initialize and start the OpenEJB container during the launch of the application.
import org.apache.openejb.OpenEjbContainer;
public class MyApp {
public static void main(String[] args) {
Properties properties = new Properties();
properties.put(OpenEjbContainer.OPENEJB_EMBEDDED_REMOTABLE, "true");
EJBContainer ejbContainer = EJBContainer.createEJBContainer(properties);
// The logic after the container starts ...
ejbContainer.close();
// The logic after the container is closed ...
}
}
5. Use EJB components
Once the OpenEjb container is successfully started, you can use the EJB component.You can obtain an EJB instance through JNDI search and call its method.
import javax.naming.InitialContext;
import com.example.MyBean;
public class MyAppClient {
public static void main(String[] args) {
InitialContext context = new InitialContext();
MyBean myBean = (MyBean) context.lookup("java:global/myapp/MyBean");
myBean.doSomething();
}
}
In the sample code, use the Ibean's instance through JNDI using the InitialContext object, and then call its Dosomething method.
Through the above steps, you can use OpenEjb's core framework in the Java library to build and manage EJB applications.I hope the usage guidelines and Java code examples provided in this article can help you better understand and apply OpenEjb.
