Spring AnnotationConfigApplicationContext

Spring AnnotationConfigApplicationContext

概述

• 通常Spring XML文件用来作为ClassPathXmlApplicationContext 的初始化。@Configuration 标注的类能够用来初始化AnnotationConfigApplicationContext类，这样就可以提供Spring容器的完全的自由的无XML用法
• AnnotationConfigApplicationContext继承GenericApplicationContext这个通用应用上下文，GenericApplicationContext内部定义了一个DefaultListableBeanFactory实例，GenericApplicationContext实现了BeanDefinitionRegistry接口，所以可以通过AnnotationConfigApplicationContext实例注册bean defintion，然后调用refresh()方法来初始化上下文。
• AnnotationConfigApplicationContext继承AbstractApplicationContext，AbstractApplicationContext提供了ApplicationContext的抽象实现。

示例

package com.myapp.config;
import com.myapp.Entitlement;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class AppConfig {
    @Bean(name="entitlement")
    public Entitlement entitlement() {
        Entitlement ent= new Entitlement();
        ent.setName("Entitlement");
        ent.setTime(1);
        return ent;
    }

    @Bean(name="entitlement2")
    public Entitlement entitlement2() {
        Entitlement ent= new Entitlement();
        ent.setName("Entitlement2");
        ent.setTime(2);
        return ent;
    }
}

package com.myapp;
public class Entitlement {
    private String name;
    private int time;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getTime() {
        return time;
    }
    public void setTime(int time) {
        this.time = time;
    }
}

package com.myapp;

import com.myapp.config.AppConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class JavaConfigTest {
    public static void main(String[] arg) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        ctx.register(AppConfig.class);
        ctx.refresh();

        Entitlement ent = (Entitlement)ctx.getBean("entitlement");
        System.out.println(ent.getName());
        System.out.println(ent.getTime());

        Entitlement ent2 = (Entitlement)ctx.getBean("entitlement2");
        System.out.println(ent2.getName());
        System.out.println(ent2.getTime());

        ctx.close();
    }
}