spring全注解的方式构建web三层结构

最近在看spring framework 的官方文档，看到spring的全注解的方式来dao,serviece,controller，没有xml，感觉非常的方便，所以在此记录一下

环境：maven项目，jdk1.8,spring-4.3.5

1.首先配置spring配置java类，此操作相当于原来的配置xml文件，java类如下：

SpringIocXmlConfig.java类

package org.spring.ioc.core.config;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;@Configuration//表明这是一个配置管理java类，这个java类相当于spring.xml 文件@ComponentScan(basePackages="org.spring.ioc.core")//指明采用注解的方式--扫描org.spring.ioc.core这个包下（包括子包）所用的注解，例如@Service,@Controller,@Autowire等等public class SpringIocXmlConfig {}

2.配置dao层，有两个文件SpringIocDao.java接口和SpringIocDaoImpl.java实现类

SpringIocDao.java类

package org.spring.ioc.core.dao;public interface SpringIocDao {void testAnnotation();}

SpringIocDaoImpl.java实现类

package org.spring.ioc.core.dao.impl;import org.spring.ioc.core.dao.SpringIocDao;import org.springframework.stereotype.Repository;@Repository//默认情况下向IOC 容器中注入一个名为“springIocDaoImpl"，即在默认情况下注入的是类名（首字母小写）这里可以用@Repository("springIocDaoImpl")代替public class SpringIocDaoImpl implements SpringIocDao {@Overridepublic void testAnnotation() {System.out.println("spring ioc annotation test successful");}}

3.配置service层，两个文件SpringIocService接口，SpringIocServiceImpl实现类

SpringIocService接口

package org.spring.ioc.core.service;public interface SpringIocService {void testAnnotation();}

SpringIocServiceImpl实现类

package org.spring.ioc.core.service.impl;import org.spring.ioc.core.dao.SpringIocDao;import org.spring.ioc.core.service.SpringIocService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;@Service//解释同@Repositorypublic class SpringIocServiceImpl implements SpringIocService {@Autowired//默认是按类型进行装配，如果有两个SpringIocDao的实现，则需用@Qualifier("实现类在IOC中的名称")进行注释public SpringIocDao springIocDao;@Overridepublic void testAnnotation() {springIocDao.testAnnotation();}}

4.controller层 ，一个java文件，SpringIocController.java文件
SpringIocController.java类

package org.spring.ioc.core.controller;import org.spring.ioc.core.bean.NoInterfaceBean;import org.spring.ioc.core.service.SpringIocService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Controller;@Controller//经过测试发现@Controller默认情况下是向spring IOC容器中注入一个名为“springIocController”的bean，相当于@Controller("springIocController")public class SpringIocController {@Autowiredprivate SpringIocService springIocService;@Autowiredprivate NoInterfaceBean noInterfaceBean;public void testAnnotation(){springIocService.testAnnotation();}public void testNointerfaceAnnotation(){noInterfaceBean.testNointerfaceAnnotation();}}

5.测试类

SpringAnnotationMain.java类

package org.spring.ioc.core.test;import org.spring.ioc.core.config.SpringIocXmlConfig;import org.spring.ioc.core.controller.SpringIocController;import org.springframework.context.ApplicationContext;import org.springframework.context.annotation.AnnotationConfigApplicationContext;/*** 测试spring（采用全注解的方式）* @author lijun**/public class SpringAnnotationMain {public static void main(String[] args) {@SuppressWarnings("resource")ApplicationContext context = new AnnotationConfigApplicationContext(SpringIocXmlConfig.class);//加载配置文件，这里是加载一个java类，相当于以前的加载xmlSpringIocController controller = context.getBean("springIocController",SpringIocController.class);//得到SpringIocController实例controller.testAnnotation();controller.testNointerfaceAnnotation();}}

根据以上代码即可搭建一个全注解的springIOC三层结构，输出的结果为

log4j:WARN No appenders could be found for logger (org.springframework.core.env.StandardEnvironment).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
spring ioc annotation test successful
spring ioc annotation no interface