Spring Boot实战(2) Spring常用配置 / 憋错料

1. Bean的Scope

scope描述Spring容器如何新建Bean的实例。通过注解@Scope实现，取值有：

a. Singleton：一个Spring容器中只有一个Bean的实例。此为Spring的默认配置，全容器共享一个实例。

b. Prototype：每次调用新建一个Bean的实例

c. Request：Web项目中，给每一个Http Request新建一个Bean实例

d. Session：Web项目中，给每一个Http Session新建一个Bean实例

e. GlobalSession：这个只在portal应用中有用，给每一个global http session新建一个Bean实例。

示例：演示Singleton和Prototype分别从Spring容器中获取2次Bean，判断Bean的实例是否相等

1) 编写Singleton的Bean

  1 package com.ws.study.scope;
  2
  3 import org.springframework.stereotype.Service;
  4
  5 // 默认为Singleton，等同于@Scope("singleton")
  6 @Service
  7 public class DemoSingletonService {
  8 }
  9

2) 编写Prototype的Bean

  1 package com.ws.study.scope;
  2
  3 import org.springframework.context.annotation.Scope;
  4 import org.springframework.stereotype.Service;
  5
  6 @Service
  7 // 声明为Prototype
  8 @Scope(value = "prototype")
  9 public class DemoPrototypeService {
 10 }

3) 配置类

  1 package com.ws.study.scope;
  2
  3 import org.springframework.context.annotation.ComponentScan;
  4 import org.springframework.stereotype.Component;
  5
  6 @Component
  7 @ComponentScan("com.ws.study.scope")
  8 public class ScopeConfig {
  9 }
 10

4) 运行类

  1 package com.ws.study.scope;
  2
  3 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  4
  5 public class Main {
  6
  7 	public static void main(String[] args) {
  8 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ScopeConfig.class);
  9
 10 		DemoSingletonService s1 = context.getBean(DemoSingletonService.class);
 11 		DemoSingletonService s2 = context.getBean(DemoSingletonService.class);
 12 		System.out.println("s1与s2是否相等："+s1.equals(s2));
 13
 14 		DemoPrototypeService p1 = context.getBean(DemoPrototypeService.class);
 15 		DemoPrototypeService p2 = context.getBean(DemoPrototypeService.class);
 16 		System.out.println("p1与p2是否相等："+p1.equals(p2));
 17 	}
 18
 19 }
 20

5) 运行结果

  1 五月 30, 2018 11:13:15 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
  2 信息: Refreshing org.spring[email protected]183da3f: startup date [Wed May 30 23:13:15 CST 2018]; root of context hierarchy
  3 s1与s2是否相等：true
  4 p1与p2是否相等：false
  5 五月 30, 2018 11:13:15 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
  6 信息: Closing org.spring[email protected]183da3f: startup date [Wed May 30 23:13:15 CST 2018]; root of context hierarchy
  7

2. Spring EL和资源调用

Spring EL为Spring表达式语言，支持在xml和注解中使用表达式。Spring EL实现普通文件、网址、配置文件、系统环境变量等资源的注入。Spring主要在@Value的参数中使用表达式。

示例：

1) 加入commons-io依赖

  1 		<dependency>
  2 			<groupId>commons-io</groupId>
  3 			<artifactId>commons-io</artifactId>
  4 			<version>2.3</version>
  5 		</dependency>

2) 包下创建text.txt，内容随意，此示例写入如下：

  1 Spring

3) 包下新建test.properties

  1 test.content=spring
  2 test.date=2018

4) 需被注入的Bean

  1 package com.ws.study.el;
  2
  3 import org.springframework.beans.factory.annotation.Value;
  4 import org.springframework.stereotype.Service;
  5
  6 @Service
  7 public class DemoService {
  8 	// 注入普通字符串
  9 	@Value("其他类的属性")
 10 	private String another;
 11
 12 	public String getAnother() {
 13 		return another;
 14 	}
 15
 16 	public void setAnother(String another) {
 17 		this.another = another;
 18 	}
 19 }
 20

5) 配置类

  1 package com.ws.study.el;
  2
  3 import org.apache.commons.io.IOUtils;
  4 import org.springframework.beans.factory.annotation.Autowired;
  5 import org.springframework.beans.factory.annotation.Value;
  6 import org.springframework.context.annotation.Bean;
  7 import org.springframework.context.annotation.ComponentScan;
  8 import org.springframework.context.annotation.PropertySource;
  9 import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
 10 import org.springframework.core.env.Environment;
 11 import org.springframework.core.io.Resource;
 12 import org.springframework.stereotype.Component;
 13
 14 @Component
 15 @ComponentScan("com.ws.study.el")
 16 // 注入加载的配置文件
 17 @PropertySource("classpath:com/ws/study/el/test.properties")
 18 public class ElConfig {
 19
 20 	// 注入普通字符串
 21 	@Value("I love you")
 22 	private String normal;
 23
 24 	// 注入操作系统属性
 25 	@Value("#{systemProperties[‘os.name‘]}")
 26 	private String osName;
 27
 28 	// 注入表达式结果
 29 	@Value("#{ T(java.lang.Math).random() * 100.0 }")
 30 	private double randomNumber;
 31
 32 	// 注入其他Bean属性
 33 	@Value("#{demoService.another}")
 34 	private String fromAnother;
 35
 36 	// 注入文件资源
 37 	@Value("classpath:com/ws/study/el/test.txt")
 38 	private Resource testFile;
 39
 40 	// 注入Url
 41 	@Value("https://www.baidu.com")
 42 	private Resource testUrl;
 43
 44 	// 注入配置文件
 45 	// 如果没有上述的@PropertySource，而使用需要@Value加载配置文件，则需配置一个PropertySourcesPlaceholderConfigurer的Bean
 46 	@Value("${test.content}")
 47 	private String content;
 48
 49 	// 注入配置文件也可以从Environment获取
 50 	@Autowired
 51 	private Environment environment;
 52
 53 	@Bean
 54 	public static PropertySourcesPlaceholderConfigurer propertyConfigure(){
 55 		return new PropertySourcesPlaceholderConfigurer();
 56 	}
 57
 58 	public void outputResource(){
 59 		try {
 60 			System.out.println(normal);
 61 			System.out.println(osName);
 62 			System.out.println(randomNumber);
 63 			System.out.println(fromAnother);
 64 			System.out.println(IOUtils.toString(testFile.getInputStream()));
 65 			System.out.println(IOUtils.toString(testUrl.getInputStream()));
 66 			System.out.println(content);
 67 			System.out.println(environment.getProperty("test.content"));
 68 		} catch (Exception e) {
 69 		}
 70 	}
 71 }
 72

6) 运行类

  1 package com.ws.study.el;
  2
  3 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  4
  5 public class Main {
  6 	public static void main(String[] args) {
  7 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ElConfig.class);
  8 		ElConfig elConfig = context.getBean(ElConfig.class);
  9 		elConfig.outputResource();
 10 		context.close();
 11 	}
 12 }
 13

7) 运行结果

  1 五月 31, 2018 10:04:31 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
  2 信息: Refreshing org.spring[email protected]1bc7afb: startup date [Thu May 31 22:04:31 CST 2018]; root of context hierarchy
  3 I love you
  4 Windows 7
  5 81.51080310192492
  6 其他类的属性
  7 Spring
  8 <!DOCTYPE html>
  9 <!--STATUS OK--><html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css href=https://ss1.bdstatic.com/5eN1bjq8AAUYm2zgoY3K/r/www/cache/bdorz/baidu.min.css><title>百度一下，你就知道</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class=head_wrapper> <div class=s_form> <div class=s_form_wrapper> <div id=lg> <img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class=fm> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class=s_ipt value maxlength=255 autocomplete=off autofocus=autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn" autofocus></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>新闻</a> <a href=https://www.hao123.com name=tj_trhao123 class=mnav>hao123</a> <a href=http://map.baidu.com name=tj_trmap class=mnav>地图</a> <a href=http://v.baidu.com name=tj_trvideo class=mnav>视频</a> <a href=http://tieba.baidu.com name=tj_trtieba class=mnav>贴吧</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&amp;tpl=mn&amp;u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class=lb>登录</a> </noscript> <script>document.write(‘<a href="http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u=‘+ encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ ‘" name="tj_login" class="lb">登录</a>‘);
 10                 </script> <a href=//www.baidu.com/more/ name=tj_briicon class=bri style="display: block;">更多产品</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>关于百度</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>&copy;2017&nbsp;Baidu&nbsp;<a href=http://www.baidu.com/duty/>使用百度前必读</a>&nbsp; <a href=http://jianyi.baidu.com/ class=cp-feedback>意见反馈</a>&nbsp;京ICP证030173号&nbsp; <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html>
 11
 12 spring
 13 spring
 14 五月 31, 2018 10:07:34 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
 15 信息: Closing org.spring[email protected]1bc7afb: startup date [Thu May 31 22:04:31 CST 2018]; root of context hierarchy
 16

3. Bean的初始化和销毁

(1) Spring对Bean的生命周期的操作提供了支持。对于Java配置方式，使用@Bean的initMethod和destroyMethod(相当于xml配置的init-method和destory-method)；对于注解方式，使用JSR-250的@PostConstruct和@PreDestroy

示例：

1) 增加JSR250支持

  1 		<dependency>
  2 			<groupId>javax.annotation</groupId>
  3 			<artifactId>jsr250-api</artifactId>
  4 			<version>1.0</version>
  5 		</dependency>

2) 使用@Bean形式的Bean

  1 package com.ws.study.prepost;
  2
  3 public class BeanWayService {
  4
  5 	public void init(){
  6 		System.out.println("@Bean-init-method");
  7 	}
  8
  9 	public BeanWayService(){
 10 		super();
 11 		System.out.println("初始化构造函数-BeanWayService");
 12 	}
 13
 14 	public void destory(){
 15 		System.out.println("@Bean-destroy-method");
 16 	}
 17 }
 18

3) 使用JSR250形式的Bean

  1 package com.ws.study.prepost;
  2
  3 import javax.annotation.PostConstruct;
  4 import javax.annotation.PreDestroy;
  5
  6 public class JSR250WayService {
  7
  8 	// 在构造函数执行完之后执行
  9 	@PostConstruct
 10 	public void init(){
 11 		System.out.println("jsr250-init-method");
 12 	}
 13
 14 	public JSR250WayService(){
 15 		super();
 16 		System.out.println("初始化构造函数-JSR250WayService");
 17 	}
 18
 19 	// 在Bean销毁之前执行
 20 	@PreDestroy
 21 	public void destroy(){
 22 		System.out.println("jsr250-destroy-method");
 23 	}
 24 }
 25

4) 配置类

  1 package com.ws.study.prepost;
  2
  3 import org.springframework.context.annotation.Bean;
  4 import org.springframework.context.annotation.ComponentScan;
  5 import org.springframework.context.annotation.Configuration;
  6
  7 @Configuration
  8 @ComponentScan("com.ws.study.prepost")
  9 public class PrePostConfig {
 10
 11 	// initMethod和destroyMethod指定BeanWayService类的init和destroy方法在构造之后、Bean销毁之前执行
 12 	@Bean(initMethod = "init", destroyMethod = "destory")
 13 	BeanWayService beanWayService(){
 14 		return new BeanWayService();
 15 	}
 16
 17 	@Bean
 18 	JSR250WayService jsr250WayService(){
 19 		return new JSR250WayService();
 20 	}
 21 }
 22

5) 运行类

  1 package com.ws.study.prepost;
  2
  3 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  4
  5 public class Main {
  6
  7 	public static void main(String[] args) {
  8 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(PrePostConfig.class);
  9
 10 		BeanWayService beanWayService = context.getBean(BeanWayService.class);
 11 		JSR250WayService jsr250WayService = context.getBean(JSR250WayService.class);
 12
 13 		context.close();
 14 	}
 15
 16 }
 17

6) 运行结果

  1 五月 31, 2018 10:33:21 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
  2 信息: Refreshing org.spring[email protected]dbe50f: startup date [Thu May 31 22:33:21 CST 2018]; root of context hierarchy
  3 初始化构造函数-BeanWayService
  4 @Bean-init-method
  5 初始化构造函数-JSR250WayService
  6 jsr250-init-method
  7 五月 31, 2018 10:35:58 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
  8 信息: Closing org.spring[email protected]dbe50f: startup date [Thu May 31 22:33:21 CST 2018]; root of context hierarchy
  9 jsr250-destroy-method
 10 @Bean-destroy-method
 11

4. Profile

Profile为在不同环境下使用不同的配置提供了支持(开发环境下的配置和生产环境下的配置肯定是不同的，如数据库配置)。

a. 通过设定Environment的ActiveProfiles来设定当前context需要使用的配置环境。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不同的Bean

b. 通过设定jvm的srping.profiles.active参数来设置配置环境

c. Web项目设置在Servlet的context parameter中

示例：

1) 示例Bean

  1 package com.ws.study.profile;
  2
  3 public class DemoBean {
  4
  5 	private String content;
  6
  7
  8 	public DemoBean(String content){
  9 		super();
 10 		this.content = content;
 11 	}
 12
 13 	public String getContent() {
 14 		return content;
 15 	}
 16
 17 	public void setContent(String content) {
 18 		this.content = content;
 19 	}
 20
 21 }
 22

2) Profile配置

  1 package com.ws.study.profile;
  2
  3 import org.springframework.context.annotation.Bean;
  4 import org.springframework.context.annotation.Configuration;
  5 import org.springframework.context.annotation.Profile;
  6
  7 @Configuration
  8 public class ProfileConfig {
  9
 10 	@Bean
 11 	// Profile为dev时实例化devDemoBean
 12 	@Profile("dev")
 13 	public DemoBean devDemoBean(){
 14 		return new DemoBean("from devlopment profile");
 15 	}
 16
 17 	@Bean
 18 	// Profile为prod时实例化prodDemoBean
 19 	@Profile("prod")
 20 	public DemoBean proDemoBean(){
 21 		return new DemoBean("from production profile");
 22 	}
 23 }

3) 运行类

  1 package com.ws.study.profile;
  2
  3 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  4
  5 public class Main {
  6
  7 	public static void main(String[] args) {
  8 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
  9 		// 先将活动的Profile设置为prod
 10 		context.getEnvironment().setActiveProfiles("prod");
 11 		// 后置注册Bean配置类，不然会报Bean未定义的错误
 12 		context.register(ProfileConfig.class);
 13 		// 刷新容器
 14 		context.refresh();
 15
 16 		DemoBean demoBean = context.getBean(DemoBean.class);
 17
 18 		System.out.println(demoBean.getContent());
 19
 20 		context.close();
 21 	}
 22
 23 }
 24

4) 设置为prod的运行结果

  1 五月 31, 2018 11:04:32 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
  2 信息: Refreshing org.spring[email protected]dbe50f: startup date [Thu May 31 23:04:31 CST 2018]; root of context hierarchy
  3 from production profile
  4 五月 31, 2018 11:05:05 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
  5 信息: Closing org.spring[email protected]dbe50f: startup date [Thu May 31 23:04:31 CST 2018]; root of context hierarchy
  6

5) 设置为dev的运行结果

  1 五月 31, 2018 11:06:21 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
  2 信息: Refreshing org.spring[email protected]1a71e93: startup date [Thu May 31 23:06:21 CST 2018]; root of context hierarchy
  3 from devlopment profile
  4 五月 31, 2018 11:06:22 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
  5 信息: Closing org.spring[email protected]1a71e93: startup date [Thu May 31 23:06:21 CST 2018]; root of context hierarchy
  6

5. 事件(Application Event)

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。这时我们就需要让另外一个Bean监听当前Bean所发送的事件。

Spring事件需要遵循的流程：

a. 自定义事件，继承ApplicationEvent

b. 定义事件监听器，实现ApplicationListener

c. 使用容器发布事件

示例：

1) 自定义事件

  1 package com.ws.study.event;
  2
  3 import org.springframework.context.ApplicationEvent;
  4
  5 public class DemoEvent extends ApplicationEvent{
  6 	private static final long serialVersionUID = -7872648566400668161L;
  7
  8 	private String msg;
  9
 10 	public DemoEvent(Object source, String msg) {
 11 		super(source);
 12 		this.msg = msg;
 13 	}
 14
 15 	public String getMsg() {
 16 		return msg;
 17 	}
 18
 19 	public void setMsg(String msg) {
 20 		this.msg = msg;
 21 	}
 22 }
 23

2) 事件监听器

  1 package com.ws.study.event;
  2
  3 import org.springframework.context.ApplicationListener;
  4 import org.springframework.stereotype.Component;
  5
  6 @Component
  7 // 实现ApplicationListener接口，并指定监听的时间类型
  8 public class DemoListener implements ApplicationListener<DemoEvent>{
  9
 10 	// 使用onApplicationEvent方法对消息进行接受处理
 11 	public void onApplicationEvent(DemoEvent event) {
 12 		String msg = event.getMsg();
 13 		System.out.println("我(bean-demoListener)接受到了bean-demoEvent发布的消息: "+msg);
 14 	}
 15 }
 16

3) 事件发布类

  1 package com.ws.study.event;
  2
  3 import org.springframework.beans.factory.annotation.Autowired;
  4 import org.springframework.context.ApplicationContext;
  5 import org.springframework.stereotype.Component;
  6
  7 @Component
  8 public class DemoPublisher {
  9
 10 	// 注入ApplicationContext用来发布事件
 11 	@Autowired
 12 	ApplicationContext applicationContext;
 13
 14 	public void publish(String msg){
 15 		// 使用ApplicationContext的publishEvent方法来发布
 16 		applicationContext.publishEvent(new DemoEvent(this, msg));
 17 	}
 18 }
 19

4) 配置类

  1 package com.ws.study.event;
  2
  3 import org.springframework.context.annotation.ComponentScan;
  4 import org.springframework.stereotype.Component;
  5
  6 @Component
  7 @ComponentScan("com.ws.study.event")
  8 public class EventConfig {
  9 }
 10

5) 运行类

  1 package com.ws.study.event;
  2
  3 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  4
  5 public class Main {
  6 	public static void main(String[] args) {
  7 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(EventConfig.class);
  8 		DemoPublisher demoPublisher = context.getBean(DemoPublisher.class);
  9 		demoPublisher.publish("hello application envent");
 10 		context.close();
 11 	}
 12 }
 13

6) 运行结果

  1 五月 31, 2018 11:23:18 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
  2 信息: Refreshing org.spring[email protected]dbe50f: startup date [Thu May 31 23:23:18 CST 2018]; root of context hierarchy
  3 我(bean-demoListener)接受到了bean-demoEvent发布的消息: hello application envent
  4 五月 31, 2018 11:25:15 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
  5 信息: Closing org.spring[email protected]dbe50f: startup date [Thu May 31 23:23:18 CST 2018]; root of context hierarchy
  6

原文地址：https://www.cnblogs.com/mengrennwpu/p/9114385.html

时间： 2024-08-28 22:46:35

Spring Boot实战(2) Spring常用配置

1. Bean的Scope

2. Spring EL和资源调用

3. Bean的初始化和销毁

4. Profile

5. 事件(Application Event)

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