sarath-soman/PVSContainer

Its a basic model of Dependency Injection Container in Java

PVSContainer

This is a Dependancy Injection framework. Dependencies are mentioned in Configuration classes(Classes Annotated with @Configuration). Injection is done to fields annotated with @Inject annotation directly. Also if instances of some classes are to be created by framework then the class should be annotated with @Instance

Example

Class Hello:

package com.pvs.test.greetings;

public class Hello {
    public void sayHello(){
        System.out.println("Hello");
    }
}

Class GoodBye:

package com.pvs.test.greetings;

import org.dic.core.annotation.Instance;

@Instance(name = "goodBye")
public class GoodBye {

    public void sayGoodBye(){
        System.out.println("Good Bye");
    }
}

Class BeanConfiguration:

package com.pvs.test.conf;

import org.dic.core.annotation.Bean;
import org.dic.core.annotation.Configuration;

import com.pvs.test.greetings.Hello;

@Configuration
public class BeanConfiguration {

    @Bean(name = "hello")
    public Hello getHello(){
        return new Hello();
    }
} 

Class Test:

package com.pvs.test;

import org.dic.core.InstanceFactory;

import com.pvs.test.greetings.GoodBye;
import com.pvs.test.greetings.Hello;

public class Test {

    public static void main(String[] args) {
        String packageToScan = "com.pvs.test";
        InstanceFactory factory = new InstanceFactory(packageToScan);
        Hello hello = (Hello) factory.getInstance("hello");
        GoodBye goodBye = (GoodBye) factory.getInstance("goodBye");
        hello.sayHello();
        goodBye.sayGoodBye();
    }
}

Output:

Hello

Good Bye

Example 2: Injecting instance of Hello in GoodBye Class

GoodBye class:

package com.pvs.test.greetings;

import org.dic.core.annotation.Inject;
import org.dic.core.annotation.Instance;

@Instance(name = "goodBye")
public class GoodBye {

    @Inject
    protected Hello hello;

    public void sayGoodBye(){
        System.out.println("Good Bye");
        hello.sayHello();
    }
}

Test Class :

package com.pvs.test;

import org.dic.core.InstanceFactory;

import com.pvs.test.greetings.GoodBye;

public class Test {

    public static void main(String[] args) {
        String packageToScan = "com.pvs.test";
        InstanceFactory factory = new InstanceFactory(packageToScan);       
        GoodBye goodBye = (GoodBye) factory.getInstance("goodBye");     
        goodBye.sayGoodBye();
    }
}

Output:

Good Bye

Hello