亚洲乱码中文字幕综合,中国熟女仑乱hd,亚洲精品乱拍国产一区二区三区,一本大道卡一卡二卡三乱码全集资源,又粗又黄又硬又爽的免费视频

Spring 加載多個(gè)xml配置文件的原理分析

 更新時(shí)間:2021年06月22日 14:20:31   作者:沉迷Spring  
我們知道Spring一次可以加載多個(gè)Bean定義的Xml配置文件,我們可以設(shè)想下如果讓我們來做我們會(huì)怎么做?我估計(jì)會(huì)根據(jù)配置文件的順序依次讀取并加載,那再來看看Spring是如何做的?

示例

先給出兩個(gè)Bean的配置文件:

spring-configlication.xml:

<?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"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop.xsd">

    <bean id="person" class="com.john.aop.Person">
    </bean>
    <bean id="ChineseFemaleSinger" class="com.john.beanFactory.Singer" abstract="true" >
        <property name="country" value="中國(guó)"/>
        <property name="gender" value="女"/>
    </bean>

</beans>

spring-config-instance-factory.xml

<?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"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop.xsd">
    <bean id="carFactory" class="com.john.domain.CarFactory" />
    <!--實(shí)例工廠方法創(chuàng)建bean-->
    <bean id="instanceCar" factory-bean="carFactory" factory-method="createCar">
        <constructor-arg ref="brand"/>
    </bean>
    <bean id="brand" class="com.john.domain.Brand" />
</beans>

java示例代碼

public class ConfigLocationsDemo {

    public static void main(String[] args) {

        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext();
        applicationContext.setConfigLocations("spring-configlocation.xml","spring-config-instance-factory.xml");
        applicationContext.refresh();
         String[] beanNames = applicationContext.getBeanDefinitionNames();
        for (String beanName : beanNames) {
            System.out.println(beanName);
        }
    }
}

這樣我們就會(huì)在控制臺(tái)打印出兩個(gè)配置文件中所有的Bean.

person
ChineseFemaleSinger
carFactory
instanceCar
brand

Process finished with exit code 0

實(shí)現(xiàn)

AbstractRefreshableConfigApplicationContext

從類的名字推導(dǎo)出這是一個(gè)帶刷新功能并且?guī)渲霉δ艿膽?yīng)用上下文。

/**
     * Set the config locations for this application context.
     * <p>If not set, the implementation may use a default as appropriate.
     */
    public void setConfigLocations(@Nullable String... locations) {
        if (locations != null) {

            this.configLocations = new String[locations.length];
            for (int i = 0; i < locations.length; i++) {
                this.configLocations[i] = resolvePath(locations[i]).trim();
            }
        }
        else {
            this.configLocations = null;
        }
    }

這個(gè)方法很好理解,首先根據(jù)傳入配置文件路徑字符串?dāng)?shù)組遍歷,并且里面調(diào)用了resolvePath方法解析占位符。那么我們要想下了,這里只做了解析占位符并且把字符串賦值給configLocations變量,那必然肯定會(huì)在什么時(shí)候去讀取這個(gè)路徑下的文件并加載bean吧?會(huì)不會(huì)是在應(yīng)用上下文調(diào)用refresh方法的時(shí)候去加載呢?帶著思考我們來到了應(yīng)用上下文的refresh方法。

AbstractApplicationContext

     @Override
    public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {

            // Tell the subclass to refresh the internal bean factory.
            //告訴子類刷新 內(nèi)部BeanFactory
            //https://www.iteye.com/blog/rkdu2-163-com-2003638
            //內(nèi)部會(huì)加載bean定義
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
      }
    }

    /**
     * Tell the subclass to refresh the internal bean factory.
     * @return the fresh BeanFactory instance
     * @see #refreshBeanFactory()
     * @see #getBeanFactory()
     */
    //得到刷新過的beanFactory
    protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
        //抽象類AbstractRefreshableApplicationContext
        //里面會(huì)加載bean定義
        //todo 加載bean定義
        refreshBeanFactory();
        //如果beanFactory為null 會(huì)報(bào)錯(cuò)
        return getBeanFactory();
    }

    /**
     * Subclasses must implement this method to perform the actual configuration load.
     * The method is invoked by {@link #refresh()} before any other initialization work.
     * <p>A subclass will either create a new bean factory and hold a reference to it,
     * or return a single BeanFactory instance that it holds. In the latter case, it will
     * usually throw an IllegalStateException if refreshing the context more than once.
     * @throws BeansException if initialization of the bean factory failed
     * @throws IllegalStateException if already initialized and multiple refresh
     * attempts are not supported
     */
    //AbstractRefreshableApplicationContext 實(shí)現(xiàn)了此方法
    //GenericApplicationContext 實(shí)現(xiàn)了此方法
    protected abstract void refreshBeanFactory() throws BeansException, IllegalStateException;

我們看到refreshBeanFactory的第一句注釋就提到了Subclasses must implement this method to perform the actual configuration load,意思就是子類必須實(shí)現(xiàn)此方法來完成最終的配置加載,那實(shí)現(xiàn)此方法的Spring內(nèi)部默認(rèn)有兩個(gè)類,AbstractRefreshableApplicationContext和GenericApplicationContext,這里我們就關(guān)心AbstractRefreshableApplicationContext:

AbstractRefreshableApplicationContext

我們要時(shí)刻記得上面的AbstractRefreshableConfigApplicationContext類是繼承于AbstractRefreshableApplicationContext的,到這里我們給張類關(guān)系圖以便加深理解:

/**
     * This implementation performs an actual refresh of this context's underlying
     * bean factory, shutting down the previous bean factory (if any) and
     * initializing a fresh bean factory for the next phase of the context's lifecycle.
     */
    @Override
    protected final void refreshBeanFactory() throws BeansException {

         //判斷beanFactory 是否為空
        if (hasBeanFactory()) {
            destroyBeans();
            closeBeanFactory(); //設(shè)置beanFactory = null
        }
        try {
            DefaultListableBeanFactory beanFactory = createBeanFactory();
            //加載Bean定義
            //todo AbstractXmlApplicationContext 子類實(shí)現(xiàn) 放入beandefinitionMap中
            loadBeanDefinitions(beanFactory);
        }
        catch (IOException ex) {
            throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
        }
    }

這里就看到了前篇文章提到一個(gè)很重要的方法loadBeanDefinitions,我們?cè)倌贸鰜砘仡櫹录由罾斫猓?/p>

/**
     * Load bean definitions into the given bean factory, typically through
     * delegating to one or more bean definition readers.
     * @param beanFactory the bean factory to load bean definitions into
     * @throws BeansException if parsing of the bean definitions failed
     * @throws IOException if loading of bean definition files failed
     * @see org.springframework.beans.factory.support.PropertiesBeanDefinitionReader
     * @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
     */
    protected abstract void loadBeanDefinitions(DefaultListableBeanFactory beanFactory)
            throws BeansException, IOException;

這里因?yàn)槲覀兪遣捎脁ml配置的,那么肯定是XmlBeanDefinitionReader無(wú)疑,我們?cè)倩仡櫹聦?shí)現(xiàn)此方法的AbstractXmlApplicationContext:

AbstractXmlApplicationContext

/**
     * Loads the bean definitions via an XmlBeanDefinitionReader.
     * @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
     * @see #initBeanDefinitionReader
     * @see #loadBeanDefinitions
     */
    //todo 重載了 AbstractRefreshableApplicationContext
    @Override
    protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
        //忽略代碼。。
        loadBeanDefinitions(beanDefinitionReader);
    }

    /**
     * Load the bean definitions with the given XmlBeanDefinitionReader.
     * <p>The lifecycle of the bean factory is handled by the {@link #refreshBeanFactory}
     * method; hence this method is just supposed to load and/or register bean definitions.
     * @param reader the XmlBeanDefinitionReader to use
     * @throws BeansException in case of bean registration errors
     * @throws IOException if the required XML document isn't found
     * @see #refreshBeanFactory
     * @see #getConfigLocations
     * @see #getResources
     * @see #getResourcePatternResolver
     */
    //bean工廠的生命周期由 refreshBeanFactory 方法來處理
    //這個(gè)方法只是 去加載和注冊(cè) bean定義
    protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {
        //ClassPathXmlApplicationContext
        Resource[] configResources = getConfigResources();
        if (configResources != null) {
            reader.loadBeanDefinitions(configResources);
        }
        String[] configLocations = getConfigLocations();
        if (configLocations != null) {
            //抽象AbstractBeanDefinitionReader里去加載
            reader.loadBeanDefinitions(configLocations);
        }
    }

這里我們終于到了這個(gè)configLocations的用武之地,它就傳入了XmlBeanDefinitionReader的loadBeanDefinitions方法中。在這里我們也看到了Spring首先會(huì)根據(jù)configResources加載BeanDefinition,其次才會(huì)去根據(jù)configLocations配置去加載BeanDefinition。到這里我們可以學(xué)到Spring中對(duì)面向?qū)ο笾蟹庋b,繼承和多態(tài)的運(yùn)用。下篇文章我們繼續(xù)剖析Spring關(guān)于Xml加載Bean定義的點(diǎn)滴。

以上就是Spring 加載多個(gè)xml配置文件的原理分析的詳細(xì)內(nèi)容,更多關(guān)于Spring 加載xml配置文件的資料請(qǐng)關(guān)注腳本之家其它相關(guān)文章!

相關(guān)文章

  • Java位掩碼控制權(quán)限與(&)或(|)非(~)、>的介紹

    Java位掩碼控制權(quán)限與(&)或(|)非(~)、>的介紹

    今天小編就為大家分享一篇關(guān)于Java位掩碼控制權(quán)限與(&)或(|)非(~)、>的介紹,小編覺得內(nèi)容挺不錯(cuò)的,現(xiàn)在分享給大家,具有很好的參考價(jià)值,需要的朋友一起跟隨小編來看看吧
    2019-03-03
  • javax.validation.constraints注解使用

    javax.validation.constraints注解使用

    這篇文章主要介紹了javax.validation.constraints注解使用方式,具有很好的參考價(jià)值,希望對(duì)大家有所幫助,如有錯(cuò)誤或未考慮完全的地方,望不吝賜教
    2024-07-07
  • SpringBoot調(diào)用第三方接口的幾種方式小結(jié)

    SpringBoot調(diào)用第三方接口的幾種方式小結(jié)

    在項(xiàng)目中調(diào)用第三方接口時(shí),確實(shí)需要根據(jù)項(xiàng)目的技術(shù)棧、架構(gòu)規(guī)范以及具體的業(yè)務(wù)需求來選擇最適合的調(diào)用方式,下面我們就介紹幾種調(diào)用第三方接口的實(shí)現(xiàn)方式以及代碼示例,需要的朋友可以參考下
    2024-07-07
  • Java窗體動(dòng)態(tài)加載磁盤文件的實(shí)現(xiàn)方法

    Java窗體動(dòng)態(tài)加載磁盤文件的實(shí)現(xiàn)方法

    這篇文章主要介紹了Java窗體動(dòng)態(tài)加載磁盤文件的實(shí)現(xiàn)方法,需要的朋友可以參考下
    2014-03-03
  • java Bean與json對(duì)象間的轉(zhuǎn)換實(shí)例講解

    java Bean與json對(duì)象間的轉(zhuǎn)換實(shí)例講解

    在本篇文章里小編給大家整理的是關(guān)于java Bean與json間的轉(zhuǎn)換的實(shí)例內(nèi)容,有需要的朋友們吧可以學(xué)習(xí)參考下。
    2020-01-01
  • 通過java字節(jié)碼分析學(xué)習(xí)對(duì)象初始化順序

    通過java字節(jié)碼分析學(xué)習(xí)對(duì)象初始化順序

    今天用了jmock對(duì)進(jìn)行單元測(cè)試編碼,發(fā)現(xiàn)一個(gè)比較奇怪的語(yǔ)法,static使用方法,見下面例子
    2013-11-11
  • springsecurity 基本使用詳解

    springsecurity 基本使用詳解

    這篇文章主要介紹了springsecurity 基本使用,本文通過圖文并茂的形式給大家介紹的非常詳細(xì),對(duì)大家的學(xué)習(xí)或工作具有一定的參考借鑒價(jià)值,需要的朋友可以參考下
    2020-11-11
  • Java?NIO實(shí)現(xiàn)聊天系統(tǒng)

    Java?NIO實(shí)現(xiàn)聊天系統(tǒng)

    這篇文章主要為大家詳細(xì)介紹了Java?NIO實(shí)現(xiàn)聊天系統(tǒng),文中示例代碼介紹的非常詳細(xì),具有一定的參考價(jià)值,感興趣的小伙伴們可以參考一下
    2021-11-11
  • 詳解SpringBoot AOP 攔截器(Aspect注解方式)

    詳解SpringBoot AOP 攔截器(Aspect注解方式)

    這篇文章主要介紹了詳解SpringBoot AOP 攔截器 Aspect,小編覺得挺不錯(cuò)的,現(xiàn)在分享給大家,也給大家做個(gè)參考。一起跟隨小編過來看看吧
    2017-05-05
  • Spring Boot 項(xiàng)目做性能監(jiān)控的操作流程

    Spring Boot 項(xiàng)目做性能監(jiān)控的操作流程

    這篇文章主要介紹了Spring Boot 項(xiàng)目如何做性能監(jiān)控,本文通過實(shí)例代碼圖文相結(jié)合給大家介紹的非常詳細(xì),對(duì)大家的學(xué)習(xí)或工作具有一定的參考借鑒價(jià)值,需要的朋友可以參考下
    2020-07-07

最新評(píng)論