2.1 Bean的Scope

2.1.1 说明

scope描述的是Spring容器如何新建的实例的。Spring的Scope有几种，通过@Scope注解来实现。

1）Singleton：一个Spring容器中只有一个Bean 的实例，也是Spring的默认配置，全容器共享一个实例。

2）Prototype：每次调用创建一个实例。

3）Request：Web项目中，给每一个http request创建一个Bean实例。

4) Session：Web项目中，给每一个http session创建一个Bean实例。

2.1.2 实例

1）编写Singleton的Bean

package com.dy.spring_demo.ch2.scope;
import org.springframework.stereotype.Service;
/**
* Author:dy_bom
* Description: 单例
* Date:Created in 下午9:59 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Service //默认使用单例 相当于@Scope("singleton)public class DemoSingletonService {}

2）编写prototype的Bean

package com.dy.spring_demo.ch2.scope;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Service;
/**
* Author:dy_bom
* Description: 多例
* Date:Created in 下午10:01 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Service@Scope("prototype") // 多例public class DemoPrototypeService {}

3）配置

package com.dy.spring_demo.ch2.scope;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
/**
* Author:dy_bom
* Description: Scope配置
* Date:Created in 下午10:03 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Configuration@ComponentScan("com.dy.spring_demo.ch2.scope")public class ScopeConfig {}

4）运行

package com.dy.spring_demo.ch2.scope;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午10:04 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/public class Main {
 public static void main(String[] args) {
 AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ScopeConfig.class);
 DemoSingletonService s1 = context.getBean(DemoSingletonService.class);
 DemoSingletonService s2 = context.getBean(DemoSingletonService.class);
 DemoPrototypeService p1= context.getBean(DemoPrototypeService.class);
 DemoPrototypeService p2= context.getBean(DemoPrototypeService.class);
 System.out.println("单例模式下，s1是否与s2相等："+s1.equals(s2));
 System.out.println("多例模式下，p1是否与p2相等："+p1.equals(p2));
 }
}
context.close();

结果如下

单例模式下，s1是否与s2相等：true多例模式下，p1是否与p2相等：false

2.2 Spring EL和资源的调用

2.2.1 说明

Spring EL-Spring表达式语言，支持在xml和注解中使用表达式，类似于JSP的EL表达式语言。

Spring 主要是在注解@Value的参数中使用表达式

2.2.2 实例

1）增加commons-io的依赖

 <properties>
 <commons-io.version>2.5/<commons-io.version>
 /<properties>

 <dependency>
 <groupid>commons-io/<groupid>
 <artifactid>commons-io/<artifactid>
 <version>${commons-io.version}/<version>
 /<dependency>

2）需要注入的Bean

package com.dy.spring_demo.ch2.el;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午10:16 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Servicepublic class DemoElService {
 @Value("其他类型的属性") //注解注入普通字符串
 private String userName; public String getUserName() { return userName;
 } public void setUserName(String userName) { this.userName = userName;
 }
}

3）配置

package com.dy.spring_demo.ch2.el;
import org.apache.commons.io.Charsets;
import org.apache.commons.io.IOUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration; 

import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.core.env.Environment;
import org.springframework.core.io.Resource;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午10:18 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Configuration
@ComponentScan("com.dy.spring_demo.ch2.el")
@PropertySource("classpath:com.dy.spring_demo.ch2.el.ElConfig/el.properties") //配置文件
public class ElConfig {
 @Value("普通属性") //注入普通属性
 private String normal; 
 @Value("#{systemProperties['os.name']}") //注入操作系统属性
 private String osName; 
 @Value("#{demoElService.userName}") //注入其他Bean的属性
 private String fromOtherBean; 
 @Value("#{T(java.lang.Math).random() * 100.0}") //注入表达式结果
 private double randomNum; 
 @Value("classpath:com.dy.spring_demo.ch2.el.ElConfig/el.properties") //注入文件资源
 private Resource elFile; 
 @Value("http://www.baidu.com") //注入网络资源
 private Resource baiDuUrl; 
 @Value("${project.author}") //注入配置文件
 private String author; 
 @Autowired
 private Environment environment; //注入环境配置 
 @Bean
 public static PropertySourcesPlaceholderConfigurer placeholderConfigurer(){
 return new PropertySourcesPlaceholderConfigurer();
 }
 public void outPutResource(){
 try {
 System.out.println(normal);
 System.out.println(osName);
 System.out.println(fromOtherBean);
 System.out.println(randomNum);
 System.out.println(IOUtils.toString(elFile.getInputStream(), Charsets.requiredCharsets().lastKey()));
 System.out.println(IOUtils.toString(baiDuUrl.getInputStream(), Charsets.requiredCharsets().lastKey()));
 System.out.println(author);
 System.out.println(environment.getProperty("project.name"));
 }catch (Exception e){ 

 e.printStackTrace();
 }
 }
}

4）运行

普通属性
Mac OS X
其他类型的属性
22.75653062028422
project.author = dy_bom
project.name = spring-demo <link><title>百度一下，你就知道/<title>  
 
 
 
 
 
   
  
 
 
           <noscript>   /<noscript>    
 
 
 
 
 
     
 
©2017 Baidu       京ICP证030173号    
 
 
 
  dy_bom
spring-demo

2.3 Bean的初始化和销毁

2.3.1 说明

在开发的过程中，我们经常在Bean的使用之前或者之后有些必要的操作，Spring对Bean的生命周期的操作提供了支持。有如下两种方式：

1）Java的配置方式

使用@Bean的initMethod和destroyMethod。

2）注解方式

利用JSR-250的@PostConstruct和@PreDestroy。

2.3.2 实例

1）增加JSR250支持

 
 <dependency>
 <groupid>javax.annotation/<groupid>
 <artifactid>jsr250-api/<artifactid>
 <version>1.0/<version>
 /<dependency>

2）使用@Bean形式的Bean

package com.dy.spring_demo.ch2.prepost;
/**
* Author:dy_bom
* Description: @Bean形式的创建和销毁
* Date:Created in 下午10:47 2018/4/1 

* Copyright (c) [email protected] All Rights Reserved.
*/public class BeanWayService {
 public void init(){
 System.out.println("@Bean-init-method");
 } public BeanWayService(){ super();
 System.out.println("初始化构造函数-BeanWayService");
 } public void destroy(){
 System.out.println("@Bean-destroy-method");
 }
}

3）JSR250形式的Bean

package com.dy.spring_demo.ch2.prepost;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午10:50 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/public class JSR250WayService {
 @PostConstruct //1 在构造函数执行完成之后执行
 public void init(){
 System.out.println("jsr250-init-method");
 } public JSR250WayService(){ super();
 System.out.println("初始化构造函数-JSR250WayService");
 } @PreDestroy //2 在Bean销毁之前执行
 public void destroy(){
 System.out.println("jsr250-destroy-method");
 }
}

4）配置

package com.dy.spring_demo.ch2.prepost;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午10:52 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Configuration@ComponentScan("com.dy.spring_demo.ch2.prepost")public class PrePostConfig {
 @Bean(initMethod = "init",destroyMethod = "destroy") //指定initMethod和destroyMethod方法 

 BeanWayService beanWayService(){ return new BeanWayService();
 } @Bean
 JSR250WayService jsr250WayService(){ return new JSR250WayService();
 }
}

5）运行

package com.dy.spring_demo.ch2.prepost;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午10:55 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/public class Main {
 public static void main(String[] args) {
 AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(PrePostConfig.class);
 BeanWayService beanWayService = context.getBean(BeanWayService.class);
 JSR250WayService jsr250WayService = context.getBean(JSR250WayService.class);
 context.close();
 }
}

结果如下：

初始化构造函数-BeanWayService
@Bean-init-method初始化构造函数-JSR250WayServicejsr250-init-methodjsr250-destroy-method@Bean-destroy-method

2.4 Profile

2.4.1 说明

Profile在不同的环境下，提供了不同的配置支持。用如下方法设置profile的激活

1）通过设定Environment的ActiveProfiles来设定当前的context需要使用的配置环境。在开发中使用@Profile注解类或者方法，达到在不同情况下选择实例化的不同的Bean。

2）通过设定的JVM的spring.profiles.active参数来设置环境

3）Web项目设置在Servlet的context.parameter中

2.4.2 实例

1）Bean创建

package com.dy.spring_demo.ch2.profile;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午11:06 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/public class DemoProfileBean {
 private String content; public String getContent() { return content;
 } public void setContent(String content) { this.content = content;
 } public DemoProfileBean(String content) { this.content = content;
 }
}

2）配置

package com.dy.spring_demo.ch2.profile;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午11:07 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Configurationpublic class ProfileConfig {
 @Bean
 @Profile("dev") public DemoProfileBean devProfileBean(){ return new DemoProfileBean("from development profile");
 } @Bean
 @Profile("prod") public DemoProfileBean prodProfileBean(){ return new DemoProfileBean("from production profile");
 }
}

3）运行

package com.dy.spring_demo.ch2.profile;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午11:09 2018/4/1
* Copyright (c) [email protected] All Rights Reserved. 

*/public class Main {
 public static void main(String[] args) {
 AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
 context.getEnvironment().setActiveProfiles("dev"); //开发环境配置文件激活
 context.register(ProfileConfig.class);
 context.refresh();
 DemoProfileBean demoProfileBean = context.getBean(DemoProfileBean.class);
 System.out.println(demoProfileBean.getContent());
 context.close();
 }
}

结果

from development profile

2.5 事件

2.5.1 说明

Spring的事件为Bean和Bean之间的消息通信提供了支持。当一个Bean处理完一个任务之后，希望另一个Bean知道并能做相应的处理，这时，我们需要让另一个Bean监听当前Bean所发送的事件。

流程如下：

1）自定义事件，继承ApplicationEvent。

2）定义事件监听器，实现ApplicationListener。

3）使用容器发布事件。

2.5.2 实例

1）自定义事件

package com.dy.spring_demo.ch2.event;
import org.springframework.context.ApplicationEvent;
/** 

* Author:dy_bom
* Description: 自定义事件
* Date:Created in 下午11:20 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/public class DemoEvent extends ApplicationEvent {
 private String msg; public DemoEvent(Object source, String msg) { super(source); this.msg = msg;
 } public String getMsg() { return msg;
 } public void setMsg(String msg) { this.msg = msg;
 }
}

2）监听

package com.dy.spring_demo.ch2.event;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;
/**
* Author:dy_bom
* Description: 监听
* Date:Created in 下午11:22 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Componentpublic class DemoListener implements ApplicationListener<demoevent> {
 @Override
 public void onApplicationEvent(DemoEvent event) {
 String msg = event.getMsg();
 System.out.println("我是监听器，我接受到了发布的消息:"+msg);
 }
}/<demoevent>

3）发布

package com.dy.spring_demo.ch2.event;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component;
/**
* Author:dy_bom
* Description: 发布
* Date:Created in 下午11:25 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Componentpublic class DemoPublisher {
 @Autowired
 private ApplicationContext context; /**
 * 发布消息
 * @param msg
 */ 

 public void publish(String msg){
 context.publishEvent(new DemoEvent(this,msg));
 }
}

4）配置

package com.dy.spring_demo.ch2.event;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午11:26 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/@Configuration@ComponentScan("com.dy.spring_demo.ch2.event")public class EventConfig {}

5）运行

package com.dy.spring_demo.ch2.event;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
/**
* Author:dy_bom
* Description:
* Date:Created in 下午11:27 2018/4/1
* Copyright (c) [email protected] All Rights Reserved.
*/public class Main {
 public static void main(String[] args) {
 AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(EventConfig.class);
 DemoPublisher demoPublisher = context.getBean(DemoPublisher.class);
 demoPublisher.publish("Hello,dy_bom! This is a application event.");
 context.close();
 }
}

结果如下：

我是监听器，我接受到了发布的消息:Hello,dy_bom! This is a application event.