spring零配置(注解注入)

代码及结构jar包

 

Dao.java

package com.orange.test;

import org.springframework.stereotype.Repository;
/**
 * 数据访问层使用的注解
 * 默认示例化吃的类是类名并且将首字母改成小写
 * 默认实例化出来的类是单例的
 */
@Repository
public class Dao {
	public void insert() {
		System.out.println("dao insert...");
	}
	
}

Service0.java

package com.orange.test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Service;
/**
 * 业务层使用的注解
 * 可自定义实例化出的类名
 */
@Service("serviceAAA")	
@Scope("prototype")		//每次示例都是新的对象
public class Service0 {
	@Autowired	//注入属性
    private Dao dao;
	
    public void setDao(Dao dao) {
		this.dao = dao;
	}

	public void add() {
		dao.insert();
	}
}

Test.java

package com.orange.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
 *  spring 零配置 
 */
public class Test {

	public static void main(String[] args) {
		ApplicationContext context1 = new ClassPathXmlApplicationContext("beans.xml");
		Dao dao1= (Dao)context1.getBean("dao");
		Dao dao2= (Dao)context1.getBean("dao");
		Service0 serviceAAA1= (Service0)context1.getBean("serviceAAA");
		Service0 serviceAAA2= (Service0)context1.getBean("serviceAAA");
		//dao1和dao2是同一个对象
		System.out.println(dao1);	
		System.out.println(dao2);
		//serviceAAA1和serviceAAA2不是同一个对象，每次返回新的对象
		System.out.println(serviceAAA1);
		System.out.println(serviceAAA2);
		
		//测试dao类是否被注入
		serviceAAA1.add();	
	}
}

beans.xml

 

执行结果：

com.orange.test.Dao@596c2a
com.orange.test.Dao@596c2a
com.orange.test.Service0@cc70f8
com.orange.test.Service0@cdc74

dao insert...

 

打印dao insert...说明dao类已经注入，否则会报java.lang.NullPointerException异常。