Spring中基于Java的配置@Configuration和@Bean用法

Spring中为了减少xml中配置，可以声明一个配置类（例如SpringConfig）来对bean进行配置。

一、首先，需要xml中进行少量的配置来启动Java配置:

二、定义一个配置类

用@Configuration注解该类，等价 与XML中配置beans；用@Bean标注方法等价于XML中配置bean。

代码如下：

package SpringStudy;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import SpringStudy.Model.Counter;
import SpringStudy.Model.Piano;

@Configuration
public class SpringConfig {

	@Bean
	public Piano piano(){
		return new Piano();
	}
	@Bean(name = "counter") 
	public Counter counter(){
		return  new Counter(12,"Shake it Off",piano());
	}
}

三、基础类代码

Counter：

package SpringStudy.Model;

public class Counter {
	public  Counter() {
	}

	public  Counter(double multiplier, String song,Instrument instrument) {
		this.multiplier = multiplier;
		this.song = song;
		this.instrument=instrument;
	}

	private double multiplier;

	private String song;

	@Resource
	private Instrument instrument;

	public double getMultiplier() {
		return multiplier;
	}

	public void setMultiplier(double multiplier) {
		this.multiplier = multiplier;
	}


	public String getSong() {
		return song;
	}

	public void setSong(String song) {
		this.song = song;
	}

	public Instrument getInstrument() {
		return instrument;
	}

	public void setInstrument(Instrument instrument) {
		this.instrument = instrument;
	}

}

Piano类

package SpringStudy.Model;


public class Piano {
	private String name="Piano";
	private String sound;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getSound() {
		return sound;
	}

	public void setSound(String sound) {
		this.sound = sound;
	}

}

四、调用测试类

package webMyBatis;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import SpringStudy.Model.Counter;

public class SpringTest {
	public static void main(String[] args) {
		//ApplicationContext ctx = new ClassPathXmlApplicationContext("spring/bean.xml");// 读取bean.xml中的内容
		ApplicationContext annotationContext = new AnnotationConfigApplicationContext("SpringStudy");
		Counter c = annotationContext.getBean("counter", Counter.class);// 创建bean的引用对象
		System.out.println(c.getMultiplier());
		System.out.println(c.isEquals());
		System.out.println(c.getSong());
	        System.out.println(c.getInstrument().getName());
	}
}

注意：如果是在xml中配置beans和bean的话，或者使用自动扫描调用的话，代码为

ApplicationContext ctx = new ClassPathXmlApplicationContext("spring/bean.xml");// 读取bean.xml中的内容
Counter c = ctx.getBean("counter", Counter.class);// 创建bean的引用对象

五、运行结果

12.0
false
Shake it Off
Piano