With Spring 2.5 it is possible to do all configuration using the annotations. We can configure all dependency injection using the annotations, so no need to define or register your bean to the xml. You can do all wiring configuration on component bean itself using annotation.

Spring container inject dependency using the annotation first and if not found then it will search for the dependency in the xml configuration.

By default spring annotation configuration is disabled, you need to enable it explicitly. To enable the annotation driven configuration we just need to write some lines on spring configuration file.Following is the sample of xml configuration :

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

   <!-- To enable annotation driven scanning -->
   <context:annotation-config/> 
   <!-- bean definitions go here -->
</beans>

Once context:annotation-config is configured in xml configuration, now you can use the annotation in your application.

Example :

Company.java

package com.evon.example.annotaionDriven;
import org.springframework.stereotype.Component;

@Component
public class Company {
    private String companyName="Evon Technology";

    public String getCompanyName() {
        return companyName;
    }
    public void setCompanyName(String companyName) {
        this.companyName = companyName;
    } 
}

Employee.java

package com.evon.example.annotaionDriven;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class Employee {
    private String empName;
    private String department; 
    private Company company;

    public Company getCompany() {
        return company;
    }
    @Autowired
    public void setCompany(Company company) {
        this.company = company;
    }
    public String getEmpName() {
        return empName;
    }
    public void setEmpName(String empName) {
        this.empName = empName;
    }
    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }
}

bean.xml

    <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:c="http://www.springframework.org/schema/c"
      xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:annotation-config/> 
    <context:component-scan base-package="com.evon.example.annotaionDriven"/>
 </beans>

Main.java

package com.evon.example.annotaionDriven;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
public class Main {
    public static void main(String[] args) {
        ApplicationContext context = new FileSystemXmlApplicationContext("/src/main/java/com/evon/example/annotaionDriven/bean.xml");
        Employee employee = (Employee)context.getBean("employee");
        employee.setEmpName("Sumit");
        employee.setDepartment("Software Development");
        System.out.println("Employee Name : "+employee.getEmpName());
        System.out.println("Department : "+employee.getDepartment());
        System.out.println("Compnay Name : "+employee.getCompany().getCompanyName());
    }
}

Output :

Employee Name : Sumit
Department : Software Development
Compnay Name : Evon Technology

If you look at the above spring xml configuration file, you find that we have used two configurations, following is the description of those configurations:

<context:annotation-config/> : This tag will give you the freedom to use annotations in your application. <context:component-scan base-package="" /> : This tag will tell the container that look the configured beans into this directory. So the container scan the base-package, instantiate the bean and inject the dependencies.

We have lots of annotations to use in Spring application, some of those are @Required, @Autowired, @Qualifier, @Component, @Repository, @Bean etc., You can also use Java standard annotation api(JSR-330) like @Inject, @Resource, @PostConstruct, @PreDestroy etc.