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。

@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：

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

例子：

定义Store接口，及实现类StoreImpl

package com.beanannotation;
 
public interface Store {
 
}

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)

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：

<?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：

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）

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

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）

<?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

url=127.0.0.1
username=root
password=123456

单元测试：

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

jdbc.url=127.0.0.1
jdbc.username=root
jdbc.password=123456

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：

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：

@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

package com.scope;
 
public interface Store {
 
}

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

java config 实现

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：

<?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：

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。

posted @ 2017-04-19 17:57 charles999 阅读(86) 评论(0) 编辑收藏举报

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charles999

Spring_4

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

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