@Configuration

2. Configuration

介绍:

@configuration用于定义配置类,可替换xml配置文件,被注解的类的内部包含一个或者多个@bean的注解的方法,这些方法会被AnnotationConfigApplicationContext或者AnnotationConfigWebApplicationContext类进行扫描,用于构建bean的定义,初始化spring容器就相当于<beans>

加载spring的方法

配置spring并启动spring容器
相当于把该类作为spring的xml配置文件中的<beans>作用为:配置spring容器

import org.springframework.context.annotation.Configuration;

@Configuration
public class TestConfiguration {
    public TestConfiguration() {
        System.out.println("TestConfiguration容器启动初始化。。。");
    }
}

相当于

<?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" xmlns:jdbc="http://www.springframework.org/schema/jdbc"  
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:util="http://www.springframework.org/schema/util" xmlns:task="http://www.springframework.org/schema/task" xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.0.xsd
        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd
        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.0.xsd" default-lazy-init="false">
</beans>

主要的方法进行测试:

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

public class TestMain {
    public static void main(String[] args) {
        // @Configuration注解的spring容器加载方式，用AnnotationConfigApplicationContext替换ClassPathXmlApplicationContext
        ApplicationContext context = new AnnotationConfigApplicationContext(TestConfiguration.class);
        // 如果加载spring-context.xml文件：
        // ApplicationContext context = new
        // ClassPathXmlApplicationContext("spring-context.xml");
    }
}

运行之后可以看到spring容器已经启动