第二章：Spring常用配置

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>
 <!--io依赖-->
        <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.
 */
@Service
public 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
<!DOCTYPE html>
<!--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=http://s1.bdstatic.com/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></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn"></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>新闻</a> <a href=http://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>');</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>

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

        <!--增加JSR-250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-JSR250WayService
jsr250-init-method

jsr250-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.
 */
@Configuration
public 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)  xdy_0722@sina.com All Rights Reserved.
 */
@Component
public 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);
    }
}

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.
 */
@Component
public 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.

代码地址：点我
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