The technical principles and application practice of Annotations for DS framework in the Java class library
The technical principles and application practice of Annotations for DS framework in the Java class library
Overview:
Annotations for DS (referred to as DS) is a Java class library that provides a simple and powerful way to define, configure and use dependency injection and service -oriented development models.This article will introduce the technical principles and application practice of the DS framework to help developers better understand and apply the DS framework.
Technical principles:
1. Simplify dependency injection: DS framework uses annotations to define dependency relationships. Developers only need to add annotations to class or fields to enjoy the benefits of dependencies in injection.As follows:
@Component
public class MyService {
@Autowired
private MyRepository repository;
}
2. Priority use of interfaces: DS framework encourages developers to use interfaces between classes to define dependency relationships to improve the scalability and maintenance of the code.The annotation is responsible for notifying the specific choice of the DS framework to implement the class.
@Component
public class MyService {
@Autowired
private MyRepository repository;
}
public interface MyRepository {
void save(Object obj);
}
3. Follow the naming agreement: DS framework automatically registers it as a service according to the class name. Developers can use specific names to define the name and version of the service.
@Component(name = "myService")
public class MyService {
// Class body
}
Application practice:
1. Add DS framework dependencies: In the construction configuration file of the project, add the dependency item of the DS framework to use the annotations and functions of the DS framework in the project.
<dependency>
<groupId>org.apache.felix</groupId>
<artifactId>org.apache.felix.scr.annotations</artifactId>
<version>1.3.0</version>
<scope>provided</scope>
</dependency>
2. Define service components: Create a class, and use @Component annotations to mark it as a service component.You can specify the name of the service through the name attribute.
@Component(name = "myService")
public class MyService {
// Class body
}
3. Injecting dependencies: Use @Autowired annotations to mark on the fields that need to be relying on, to inform the DS framework that needs to inject specific implementation.
@Autowired
private MyRepository repository;
4. Definition interface: In order to improve the flexibility and scalability of the code, the method of defining the service service can be used.
public interface MyRepository {
void save(Object obj);
}
5. Registration service: In the configuration file of the project (such as OSGI's Manifest.mf file), register the service component as a real service so that other components can be used.
Service-Component: OSGI-INF/myService.xml
6. Configuration component: Create the MyService.xml file in the OSGI-INF directory, and configure the service component according to the XML configuration format of DS, including the service name, version, implementation class, etc.
<?xml version="1.0" encoding="UTF-8"?>
<component name="myService" version="1.0.0">
<implementation class="com.example.MyService"/>
</component>
Summarize:
Annotations for DS framework provides a convenient way to realize the development model of dependence in injection and service -oriented.By using simple annotations, define and configure the dependency of service components in the project.Developers only need to write code in accordance with certain naming and annotations and specifications to enjoy the convenience and flexibility of the DS framework.
