Spring--@configuration 和 @Bean

参考：http://wiki.jikexueyuan.com/project/spring/java-based-configuration.html

@Configuration 和 @Bean 注解

带有 @Configuration 的注解类表示这个类可以使用 Spring IoC 容器作为 bean 定义的来源。@Bean 注解告诉 Spring，一个带有 @Bean 的注解方法将返回一个对象，该对象应该被注册为在 Spring 应用程序上下文中的 bean。最简单可行的 @Configuration 类如下所示：

package org.wzh.di.demo1.congiration;

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

@Configuration
public class HelloWorldConfig {
    @Bean
    public HelloWorld helloWorld() {
        return new HelloWorld();
    }
}

package org.wzh.di.demo1.congiration;

public class HelloWorld {

    private String message;

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

}

package org.wzh.di.demo1.congiration;

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

public class Test {

    public static void main(String[] args) {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(HelloWorldConfig.class);
        HelloWorld helloWorld = ctx.getBean(HelloWorld.class);
        helloWorld.setMessage("Hello World!");
        String msg = helloWorld.getMessage();
        System.out.println(msg);
    }

}

也可以加载其他配置类，这里只写用法

package org.wzh.di.demo1.congiration;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Test2 {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        ctx.register(HelloWorldConfig.class);
        ctx.refresh();
        HelloWorld helloWorld = ctx.getBean(HelloWorld.class);
        helloWorld.setMessage("Hello World 2!");
        String msg = helloWorld.getMessage();
        System.out.println(msg);
    }

}