Spring_4

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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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1	<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：

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.

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：

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

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：

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

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。