spring Bean的三种配置方式

Spring Bean有三种配置方式：

• 传统的XML配置方式
• 基于注解的配置
• 基于类的Java Config

添加spring的maven repository

<dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <!--这个jar文件包含Spring框架基本的核心工具类，Spring其它组件要都要使用到这个包里的类，是其它组件的基本核心 -->
      <version>4.1..RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <!--这个jar文件为Spring核心提供了大量扩展 -->
      <version>4.1..RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <!--对JUNIT等测试框架的简单封装 -->
      <version>4.1..RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <!--为JDBC、Hibernate、JDO、JPA等提供的一致的声明式和编程式事务管理。-->
      <version>4.1..RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-beans</artifactId>
      <!--这个jar文件是所有应用都要用到的，它包含访问配置文件、创建和管理bean以及进行（IoC/DI）操作相关的所有类 -->
      <version>4.1..RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <!--这个jar文件包含对Spring对JDBC数据访问进行封装的所有类。 -->
      <version>4.1..RELEASE</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
    </dependency>

一、传统的XML配置方式

　　BeanFactory.java

package com.stonegeek.service;

/**
 * Created by StoneGeek on 2018/5/13.
 */
public interface BeanFactory {
    public void Beantest();
}

　　BeanFactoryImpl.java

package com.stonegeek.service.impl;

import com.stonegeek.service.BeanFactory;

/**
 * Created by StoneGeek on 2018/5/13.
 */
public class BeanFactroyImpl implements BeanFactory {
    @Override
    public void Beantest() {
        System.out.println("----------------This is a 传统的XML配置的bean!-------------------");
    }
}

　　applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
        xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    ">
    <bean id="beanFactroy" class="com.stonegeek.service.impl.BeanFactroyImpl" />

</beans>

　　TestBean1.java

package com.stonegeek;

import com.stonegeek.service.BeanFactory;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created by StoneGeek on 2018/5/13.
 */
public class TestBean1 {
    @Test
    public void test(){
        ApplicationContext ctx= new ClassPathXmlApplicationContext("applicationContext.xml");
        BeanFactory beanFactory=(BeanFactory) ctx.getBean("beanFactroy");
        beanFactory.Beantest(); //----------------This is a 传统的XML配置的bean!-------------------
    }
}

二、基于java注解的配置

　　如果一个类使用了@Service，那么此类将自动注册成一个bean，不需要再在applicationContext.xml文件定义bean了，类似的还包括@Component、@Repository、@Controller。

　　然后需要在applicationContext.xml文件中加一行，作用是自动扫描base-package包下的注解：

<context:component-scan base-package="com.stonegeek" />

　　BeanFactoryImpl.java

package com.stonegeek.service.impl;

import com.stonegeek.service.BeanFactory;
import org.springframework.stereotype.Service;

/**
 * Created by StoneGeek on 2018/5/13.
 */
@Service("beanFactory")
public class BeanFactroyImpl implements BeanFactory {
    @Override
    public void Beantest() {
        System.out.println("----------------This is a 基于Java注解的bean!-------------------");
    }
}

　　applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
        xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    ">
    <context:component-scan base-package="com.stonegeek" />

</beans>

　　TestBean2.java

package com.stonegeek;

import com.stonegeek.service.BeanFactory;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created by StoneGeek on 2018/5/13.
 */
public class TestBean2 {
    @Test
    public void test(){
        ApplicationContext ctx= new ClassPathXmlApplicationContext("applicationContext.xml");
        BeanFactory beanFactory=(BeanFactory) ctx.getBean("beanFactory");
        beanFactory.Beantest();  //This is a 基于java注解的bean！
    }
}

三、基于类的Java Config

　　通过java类定义spring配置元数据，且直接消除xml配置文件

　　Spring3.0基于java的配置直接支持下面的注解：

　　@Configuration

　　@Bean

　　@DependsOn

　　@Primary

　　@Lazy

　　@Import

　　@ImportResource

　　@Value

　　BeanFactoryImpl.java

package com.stonegeek.service.impl;

import com.stonegeek.service.BeanFactory;

/**
 * Created by StoneGeek on 2018/5/13.
 */
public class BeanFactoryImpl implements BeanFactory {
    @Override
    public void Beantest() {
        System.out.println("----------------This is a 基于类的Java Config的bean!-------------------");
    }
}

　　BeanConfig.java

package com.stonegeek.service.config;

import com.stonegeek.service.BeanFactory;
import com.stonegeek.service.impl.BeanFactoryImpl;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * Created by StoneGeek on 2018/5/13.
 */
@Configuration
public class BeanConfig {
    @Bean
    public BeanFactory beanFactory(){
        return new BeanFactoryImpl();
    }
}

　　TestBean3.java

package com.stonegeek;

import com.stonegeek.service.BeanFactory;
import com.stonegeek.service.config.BeanConfig;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

/**
 * Created by StoneGeek on 2018/5/13.
 */
public class TestBean3 {
    @Test
    public void test(){
        ApplicationContext applicationContext=new AnnotationConfigApplicationContext(BeanConfig.class);
        BeanFactory beanFactorys=applicationContext.getBean(BeanFactory.class);
        beanFactorys.Beantest();  //This is a 基于类的Java Config Bean！
    }
}

　　以上就是spring bean的三种配置方式的简单介绍！！