基于注解@Bean的配置使用方式

@Bean食用指南

@Bean功能提供了在Java类中声明Bean的方式,减少了xml文件的配置,可以极大的减少xml文件的臃肿程度.,为们得确认我们的开发环境,由于只是测试一下功能,所以需要的环境为Jdk1.8,Maven,Idea

为此 我们需要做的是

-1.确认依赖

        spring-core        spring-beans        spring-context        spring-context-support        junit4

1)先去确认一下我们需要依赖的包的版本,在此,导入spring-4.8RELEASE
在项目的pom.xml中配置

<properties>
<spring.version>4.3.8.RELEASE</spring.version>
<junit.version>4.12</junit.version>
</properties>


    <dependencies>    <dependency>            <groupId>org.springframework</groupId>            <artifactId>spring-core</artifactId>            <version>${spring.version}</version>        </dependency>       <dependency>            <groupId>org.springframework</groupId>            <artifactId>spring-beans</artifactId>            <version>${spring.version}</version>        </dependency>          <dependency>            <groupId>org.springframework</groupId>            <artifactId>spring-context</artifactId>            <version>${spring.version}</version>        </dependency>        <!--为了更好的测试,当然需要加入测试支持-->           <!--test start-->        <dependency>            <groupId>junit</groupId>            <artifactId>junit</artifactId>            <version>${junit.version}</version>        </dependency>    <dependency>            <groupId>org.springframework</groupId>            <artifactId>spring-test</artifactId>            <version>${spring.version}</version>        </dependency>       <!--end start-->    </dependencies>     ```

- 2.配置spring的XMl文件,开启组件扫描

配置文件就起名为spring-config.xml
当然 配置文件就要放在resource中

  <?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"     xmlns:context="http://www.springframework.org/schema/context" xmlns:util="http://www.springframework.org/schema/util"xsi:schemaLocation="http://www.springframework.org/schema/beans               http://www.springframework.org/schema/beans/spring-beans-3.1.xsd         http://www.springframework.org/schema/context           http://www.springframework.org/schema/context/spring-context-3.1.xsdhttp://www.springframework.org/schema/utilhttp://www.springframework.org/schema/util/spring-util-2.0.xsd">    <!-- 自动扫描 -->    <context:component-scan base-package="com.cn.nlg" />   <!-- 这个就是引入配置文件了,不过这里好像不需要用到,不过既然已经放入了util,就用一个作为示例了~    <util:properties id="jdbcConfiguration" location="classpath:jdbc.properties"/>     --></beans>

- 3.创建需要交付给Spring容器管理的Java类,别

在创建COnfiguration之前,我们先得创建一些可以放入Configuration中的Model,我们就以Film为例

根据以上信息,建立起如下model

  package com.cn.nlg.model;/** * Created by Administrator on 2017/6/8. */public interface Film {     void paly();}

package com.cn.nlg.model.JP;/** * Created by Administrator on 2017/6/8. */public class Animal extends JPFilm {    public void paly(){        System.out.println("this is Animal");    }}

package com.cn.nlg.model.JP;/** * Created by Administrator on 2017/6/8. */public class AVFilm extends JPFilm{    public void paly(){        System.out.println("this is AVFilm");    }}

package com.cn.nlg.model.JP;import com.cn.nlg.model.Film;/** * Created by Administrator on 2017/6/8. * */public class JPFilm implements Film{    public void paly(){        System.out.println("this is JPFilm");    }}

---

- 4.用@Bean在采用了@Configuration的类中愉快的使用注解声明Bean

package com.cn.nlg.BeanConfig;import com.cn.nlg.model.Film;import com.cn.nlg.model.JP.AVFilm;import com.cn.nlg.model.JP.Animal;import com.cn.nlg.model.JP.JPFilm;import com.cn.nlg.model.USA.USAFilm;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Lazy;/** * Created by Administrator on 2017/6/8. * */@Configurationpublic class FilmConfig {   //这个默认是true哦    @Lazy(false)    @Bean(name = "animal")    public Film animal(){          return new Animal();      };    @Bean(name = "avfilm")    public Film aVFilm(){        return new AVFilm();    };    @Bean(name ="jpfilm")    public Film aPFilm(){        return new JPFilm();    };    @Bean(name="usafilm")    public Film uSAFilm(){        return new USAFilm();    };    @Bean(name = "jpfilm")    public Film jpFile(){        return new JPFilm();    };}

-5当然,一个好的java程序肯定是少不了测试的,所以我们需要一个测试来试验一下是否可以运行.

现在我们来用一下junit测试一下Bean容器是否单例,是否可以运行

首先,我们得建立一个测试类,不妨就叫做:
TestSpringBeans.java

package com.cn.nlg;import com.cn.nlg.model.Film;import org.junit.Assert;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import javax.annotation.Resource;/** * Created by Administrator on 2017/6/8. */@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:spring-config.xml")public class TestSpringBeans {    @Resource(name ="animal")    Film film1;    @Resource(name ="animal")    Film film2;    @Resource(name ="jpfilm")    Film film3;    @Resource(name ="avfilm")    Film film4;    @Resource(name ="usafilm")    Film film5;    @Test    public void testSignle() {        film1.paly();        film2.paly();;        film3.paly();        film4.paly();        film5.paly();        Assert.assertTrue(film1==film2 && film2!=film3 &&film3!=film4 && film5!=film2);    }}

由此测试类就完成了,点击运行,结果应该是成功的,
控制台应该会输出如下语句
this is Animal
this is Animal
this is JPFilm
this is AVFilm
this is USAFilm

end

当然,实际上spring是需要日志依赖的.
但是管这么多干嘛~