spring中JavaConfig相关的注解

在spring3.0中增加配置spring beans的新方式JavaConfig，可以替换spring的applicataion.xml配置。也即@Configuration对等<beans/>，@Bean对等<bean/>，关于@Configuration见《spring4.0之二：@Configuration的使用》。

The following are the list of annotations introduced as part of the JavaConfig module.

@Configuration
@Bean
@DependsOn
@Primary
@Lazy
@Import
@ImportResource
@Value

In this example I have used only the first two annotations to demonstrate the basic use of JavaConfig features.

AnnotationConfigApplicationContext is the class used for loading the configuration from Java class file. Look at the below example. If you have any questions, please write it in the comments section.

1. Create JavaConfig

The following are the twp steps required for creating the Java configuration classes in the spring framework.

Annotate the class with @Configuration annotation
Annotate the method with @Bean to indicating that it is bean definition

package javabeat.net;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class JavaConfig {
    @Bean(name="userDetails")
    public UserDetails userDetails(){
        return new UserDetails();
    }
}

2. Create Bean Class

package javabeat.net;

public class UserDetails {
    private String name;
    private String phone;
    private String city;
    private String country;

        // Other methods

}

3. Load Application Context and Instantiate Bean

Create AnnotationConfigApplicationContext and get the bean instance. This is very simple example to show you how simple to configure the beans using Java class.

package javabeat.net;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class JavaConfigDemo {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(JavaConfig.class);
        UserDetails userDetails = (UserDetails) context.getBean("userDetails");
    }
}

I hope this article have helped you to understand the use of @Configuration annotation and how to use them. This has been taken as the recommended way for writing the configurations for spring applications.