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  • Spring_4

    出处：http://www.cnblogs.com/JsonShare

     

    Spring学习（13）--- 基于Java类的配置Bean 之 @Configuration & @Bean注解

     

          基于Java配置选项，可以编写大多数的Spring不用配置XML，但有几个基于Java的注释的帮助下解释。从Spring3.0开始支持使用java代码来代替XML来配置Spring，基于Java配置Spring依靠Spring的JavaConfig项目提供的很多优点。通过使用@Configuration， @Bean ，@Import ，@DependsOn 来实现Java配置Spring.

    1) @Configuration & @Bean 注解:

          在Spring的新的Java-Configuration的中间产物是基于类的@Configuration的注解和基于方法的@Bean注解。            

          @Bean注解是用来指明方法的实例化，配置和初始化一个对象是通过Spring的IoC容器来管理的。对于那些熟悉使用以XML配置Spring的<beans /> 标签，@Bean注解和<bean />标签是起相同作用的。可以在Spring的@Component注解中的类使用@Bean注解任何方法（仅仅是可以），但是，通常使用的是@Configuration

          @Configuration注解的类指明该类主要是作为一个bean的来源定义。此外，@Configuration定义的classes允许在同一个类中使用@Bean定义的方法来定义依赖的bean

          注释类与@Configuration表示这个类可以使用Spring IoC容器为bean定义来源。在@Bean 注解告诉Spring的注解为@Bean的一个方法将返回应注册为在Spring应用程序上下文中的bean对象。

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    @Configuration
    public class MovieFinder {
     
        @Bean
        public InjectionService injectionService(){
            return new InjectionServiceImpl();
        }
    }

     上面的代码将等同于下面的XML配置：

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    <bean id="movieFinder " class="com.mypackage.MovieFinder"></bean> 

     例子：

    定义Store接口，及实现类StoreImpl

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    package com.beanannotation;
     
    public interface Store {
     
    }
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    package com.beanannotation;
     
     
    public class StoreImpl implements Store {
     
        public void init(){
            System.out.println("this is init.");
        }
         
        public void destory(){
            System.out.println("this is destory.");
        }
    }

     定义StoreConfig：注意，不指定@Bean的name属性时，默认的name为方法名(即此例子的getStore)

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    package com.beanannotation;
     
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
     
    @Configuration
    public class StoreConfig {
     
        @Bean(name="store",initMethod="init",destroyMethod="destory")//若不指定name，默认为方法名
        public Store getStore(){
            return new StoreImpl();
        }
    }

      XML配置：

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    <?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-4.1.xsd
                http://www.springframework.org/schema/context
                http://www.springframework.org/schema/context/spring-context-4.1.xsd">
             
            <context:component-scan base-package="com.beanannotation">
            </context:component-scan>
             
    </beans>

     单元测试：

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    package com.beanannotation;
     
    import org.junit.Test;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
     
     
    public class UnitTest {
         
        @Test
        public void test(){
            ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-beanannotation.xml"); 
            Store service=(Store)context.getBean("store");
            System.out.println(service.getClass().getName());
            context.close();   // 关闭 Spring 容器，以触发 Bean 销毁方法的执行
        }
    }

     结果：

    复制代码
    2015-7-7 16:13:25 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@36b8bef7: startup date [Tue Jul 07 16:13:25 CST 2015]; root of context hierarchy
2015-7-7 16:13:25 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [spring-beanannotation.xml]
this is init.
2015-7-7 16:13:25 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@36b8bef7: startup date [Tue Jul 07 16:13:25 CST 2015]; root of context hierarchy
com.beanannotation.StoreImpl
this is destory.
    复制代码

    Spring学习（14）--- 基于Java类的配置Bean 之 @ImportResource & @Value 注解

     

    学习如何使用@ImportResource 和 @Value 注解进行资源文件读取

    例子：

    先创建一个MyDriverManager类（模拟读取数据库配置信息）

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    package com.beanannotation;
     
    public class MyDriverManager {
     
        public MyDriverManager(String url,String username,String password){
            System.out.println("url : "+url);
            System.out.println("username : "+username);
            System.out.println("password : "+password);
        }
    }

     创建StoreConfig

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    package com.beanannotation;
     
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.ImportResource;
     
    @Configuration
    @ImportResource("classpath:config.xml")
    public class StoreConfig {
     
        @Value("${url}")
        private String url;
         
        @Value("${username}")
        private String username;
         
        @Value("${password}")
        private String password;
         
        @Bean
        public MyDriverManager myDriverManager(){
            return new MyDriverManager(url,username,password);
        }
    }

    XML配置（context:property-placeholder 指定资源文件的位置）

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    <?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-4.1.xsd
                http://www.springframework.org/schema/context
                http://www.springframework.org/schema/context/spring-context-4.1.xsd">
             
         <context:property-placeholder location="classpath:config.properties"/>
     
         <context:component-scan base-package="com.beanannotation">
         </context:component-scan>
          
             
    </beans>

      创建资源文件config.properties

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    url=127.0.0.1
    username=root
    password=123456

     单元测试：

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    package com.beanannotation;
     
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
     
     
    public class UnitTest {
         
        @Test
        public void test(){
            ApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-beanannotation.xml"); 
            MyDriverManager service=(MyDriverManager)context.getBean("myDriverManager");
            System.out.println(service.getClass().getName());
             
        }
    }

     结果：

    复制代码
    2015-7-7 17:22:25 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@36b8bef7: startup date [Tue Jul 07 17:22:25 CST 2015]; root of context hierarchy
2015-7-7 17:22:25 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [config.xml]
2015-7-7 17:22:25 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [config.xml]
2015-7-7 17:22:25 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties
信息: Loading properties file from class path resource [config.properties]
2015-7-7 17:22:25 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties
信息: Loading properties file from class path resource [config.properties]
url : 127.0.0.1
username : Administrator
password : 123456
com.beanannotation.MyDriverManager
    复制代码

    PS：有没有发现结果有异常----username 不是root 而是计算机的当前用户名

    @Value("${username}") 在取值的时候，会去取当前用户的名称

    所以在以后的使用中，要避免使用username

    所以，修改一下config.properties 和StoreConfig

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    jdbc.url=127.0.0.1
    jdbc.username=root
    jdbc.password=123456
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    package com.beanannotation;
     
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.ImportResource;
     
    @Configuration
    @ImportResource("classpath:config.xml")
    public class StoreConfig {
     
        @Value("${jdbc.url}")
        private String url;
         
        @Value("${jdbc.username}")
        private String username;
         
        @Value("${jdbc.password}")
        private String password;
         
        @Bean
        public MyDriverManager myDriverManager(){
            return new MyDriverManager(url,username,password);
        }
    }

     测试同上：

    结果：

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    2015-7-7 17:26:41 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
    信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@32bf7190: startup date [Tue Jul 07 17:26:41 CST 2015]; root of context hierarchy
    2015-7-7 17:26:41 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
    信息: Loading XML bean definitions from class path resource [config.xml]
    2015-7-7 17:26:41 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
    信息: Loading XML bean definitions from class path resource [config.xml]
    2015-7-7 17:26:41 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties
    信息: Loading properties file from class path resource [config.properties]
    2015-7-7 17:26:41 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties
    信息: Loading properties file from class path resource [config.properties]
    url : 127.0.0.1
    username : root
    password : 123456
    com.beanannotation.MyDriverManager

     这下就可以了

    Spring学习（15）--- 基于Java类的配置Bean 之 @Bean & @Scope 注解

     

    默认@Bean是单例的，但可以使用@Scope注解来覆盖此如下：

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    @Configuration
    public class MyConfiguration {
     
        @Bean
        @Scope("prototype")
        public MovieCatalog movieCatalog(){
            //...
        }
    }

     Bean的作用域包括singleton、prototype、request、session、global session

    例子：

     新建接口Store及实现类StoreImpl

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    package com.scope;
     
    public interface Store {
     
    }
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    package com.scope;
     
    public class StoreImpl implements Store {
         
    }

     java config 实现

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    package com.scope;
     
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Scope;
     
    @Configuration
    public class StoreConfig {
     
        @Bean
        @Scope("prototype")
        public Store stringStore(){
            return new StoreImpl();
        }
    }

     XML配置：

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    <?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-4.1.xsd
                http://www.springframework.org/schema/context
                http://www.springframework.org/schema/context/spring-context-4.1.xsd">
             
            <context:component-scan base-package="com.scope">
            </context:component-scan>
             
    </beans>

     单元测试：

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    package com.scope;
     
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
     
     
    public class UnitTest {
         
        @Test
        public void test(){
            ApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-beanannotation.xml"); 
            Store store=(Store)context.getBean("stringStore");
            System.out.println(store.hashCode());
             
            Store store2=(Store)context.getBean("stringStore");
            System.out.println(store2.hashCode());
             
        }
    }

     结果：

    复制代码
    2015-7-8 9:47:11 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@36b8bef7: startup date [Wed Jul 08 09:47:11 CST 2015]; root of context hierarchy
2015-7-8 9:47:11 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [spring-beanannotation.xml]
1152423575
628012732
    复制代码

    结果发现，两个对象的hashcode不一样，说明每次取出的都是新的对象。
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  • 原文地址：https://www.cnblogs.com/charles999/p/6644210.html
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