spring framework 4 源码阅读(2)---从ClassPathXmlApplicationContext开始
Application初始化日志
15:23:12.790 [main] DEBUG o.s.core.env.StandardEnvironment - Adding [systemProperties] PropertySource with lowest search precedence 15:23:12.797 [main] DEBUG o.s.core.env.StandardEnvironment - Adding [systemEnvironment] PropertySource with lowest search precedence 15:23:12.797 [main] DEBUG o.s.core.env.StandardEnvironment - Initialized StandardEnvironment with PropertySources [systemProperties,systemEnvironment] //初始化Environment 15:23:12.803 [main] INFO o.s.c.s.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@480a6370: startup date [Mon Aug 25 15:23:12 CST 2014]; root of context hierarchy 15:23:12.861 [main] DEBUG o.s.core.env.StandardEnvironment - Adding [systemProperties] PropertySource with lowest search precedence 15:23:12.862 [main] DEBUG o.s.core.env.StandardEnvironment - Adding [systemEnvironment] PropertySource with lowest search precedence 15:23:12.862 [main] DEBUG o.s.core.env.StandardEnvironment - Initialized StandardEnvironment with PropertySources [systemProperties,systemEnvironment] //读取XML 15:23:12.880 [main] INFO o.s.b.f.xml.XmlBeanDefinitionReader - Loading XML bean definitions from class path resource [simpleContext.xml] 15:23:12.885 [main] DEBUG o.s.b.f.xml.DefaultDocumentLoader - Using JAXP provider [com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl] 15:23:12.928 [main] DEBUG o.s.b.factory.xml.BeansDtdResolver - Found beans DTD [http://www.springframework.org/dtd/spring-beans-2.0.dtd] in classpath: spring-beans-2.0.dtd //读取BeanDefinition 15:23:12.953 [main] DEBUG o.s.b.f.x.DefaultBeanDefinitionDocumentReader - Loading bean definitions //解析XML 15:23:12.971 [main] DEBUG o.s.b.f.x.BeanDefinitionParserDelegate - No XML 'id' specified - using 'simpleBean' as bean name and [] as aliases 15:23:12.986 [main] DEBUG o.s.b.f.x.BeanDefinitionParserDelegate - No XML 'id' specified - using 'anotherBean' as bean name and [] as aliases 15:23:12.986 [main] DEBUG o.s.b.f.xml.XmlBeanDefinitionReader - Loaded 3 bean definitions from location pattern [simpleContext.xml] //将获取到的BeanDefined设置到BeanFactory中 15:23:12.987 [main] DEBUG o.s.c.s.ClassPathXmlApplicationContext - Bean factory for org.springframework.context.support.ClassPathXmlApplicationContext@480a6370: org.springframework.beans.factory.support.DefaultListableBeanFactory@74bdaaa: defining beans [simpleBean,property,anotherBean]; root of factory hierarchy //初始化MessageSource,I18N中使用 15:23:13.025 [main] DEBUG o.s.c.s.ClassPathXmlApplicationContext - Unable to locate MessageSource with name 'messageSource': using default [[email protected]c5f] //application事件中心 15:23:13.029 [main] DEBUG o.s.c.s.ClassPathXmlApplicationContext - Unable to locate ApplicationEventMulticaster with name 'applicationEventMulticaster': using default [org.springframework.context.event.SimpleApplicationEventMulticaster@5629fbc9]
一些bean的初始化
一个简单的bean,里面有个属性property,以及test方法和需要进行属性注入的setProperty/** * 基本的bean方便测试 * Created by zhangya on 2014/8/13. */ public class SimpleBean { private static final Logger LOGGER = LoggerFactory.getLogger(SimpleBean.class); private SimpleBeanProperty property; /** * 简单测试方法 */ public void test() { LOGGER.info("SimpleBean is loading."); property.propertyTest(); } /** * 设置属性 property * <p>记录日志 * @param property */ public void setProperty(SimpleBeanProperty property) { LOGGER.info("Property is setting."); this.property = property; } }
作为属性赋值的bean,里面包含初始化方法
/** * 作为属性初始化的bean * Created by zhangya on 2014/8/13. */ public class SimpleBeanProperty { private static final Logger LOGGER = LoggerFactory.getLogger(SimpleBeanProperty.class); private String simpleVariable = "test567"; public SimpleBeanProperty() { LOGGER.info("SimpleBeanProperty is loading."); } /** * property的test方法 */ public void propertyTest() { LOGGER.info("propertyTest method is invoking.{}",this); } /** * 设置变量 * @param simpleVariable */ public void setSimpleVariable(String simpleVariable) { this.simpleVariable = simpleVariable; } /** * 获取变量的值 * @return 变量的值 */ public String getSimpleVariable() { return simpleVariable; } @Override public String toString() { return "SimpleBeanProperty{" + "simpleVariable='" + simpleVariable + '\'' + '}'; } }
另外一个
/** * 用于初始化的另外一个bean * @author zhangya * @category com.letume.spring.study.init * @since 2014/8/24 */ public class SimpleAnotherBean { private static final Logger LOGGER = LoggerFactory.getLogger(SimpleBeanProperty.class); private String simpleVariable = "test123"; public SimpleAnotherBean() { LOGGER.info("SimpleAnotherBean is loading."); } /** * property的test方法 */ public void test() { LOGGER.info("test method is invoking.{}",this); } /** * 设置变量 * @param simpleVariable */ public void setSimpleVariable(String simpleVariable) { this.simpleVariable = simpleVariable; } @Override public String toString() { return "SimpleAnotherBean{" + "simpleVariable='" + simpleVariable + '\'' + '}'; } }
simpleContext.xml applicationContext的配置文件,这里使用xml形式对bean进行配置
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN" "http://www.springframework.org/dtd/spring-beans-2.0.dtd"> <beans> <bean name="simpleBean" class="com.letume.spring.study.init.SimpleBean"> <property name="property"><ref local="property"/> </property> </bean> <bean id="property" name="property" class="com.letume.spring.study.init.SimpleBeanProperty" scope="prototype"/> <bean name="anotherBean" class="com.letume.spring.study.init.SimpleAnotherBean" scope="prototype"/> </beans>
下面是main函数,
例1 普通的bean初始化调用过程
/** * 简单的spring类加载的方法 * <pre> * ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(PATH+RESOURCE_CONTEXT); * SimpleBean simpleBean = context.getBean(SimpleBean.class) * simpleLoaderSimpleBean.test(); * </pre> * Created by mitchz on 2014/8/13. */ public class SimpleInit { private static final String PATH = ""; private static final String RESOURCE_CONTEXT = "simpleContext.xml"; public static void main(String[] args) throws InterruptedException { ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext( PATH + RESOURCE_CONTEXT); //获取simpleBean SimpleBean simpleBean = context .getBean("simpleBean", SimpleBean.class); simpleBean.test(); //context.registerShutdownHook(); } }
---执行单例的初始化(为什么会使用单例) 14:36:48.766 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@29d8a2c5: defining beans [simpleBean,property,anotherBean]; root of factory hierarchy 14:36:48.767 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'simpleBean' ---创建bean实例 14:36:48.767 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating instance of bean 'simpleBean' 14:36:48.786 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Eagerly caching bean 'simpleBean' to allow for resolving potential circular references ---创建属性的实例 14:36:48.799 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating instance of bean 'property' 14:36:48.799 [main] INFO c.l.s.study.init.SimpleBeanProperty - SimpleBeanProperty is loading. 14:36:48.799 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Finished creating instance of bean 'property' ---赋值 14:36:48.838 [main] INFO c.l.spring.study.init.SimpleBean - Property is setting. 14:36:48.840 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Finished creating instance of bean 'simpleBean' .... ---getBean的方法执行时,则直接从cache中取,之前初始化的实例 14:36:48.847 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Returning cached instance of singleton bean 'simpleBean' 14:36:48.847 [main] INFO c.l.spring.study.init.SimpleBean - SimpleBean is loading.SimpleBean{property=SimpleBeanProperty{simpleVariable='test567'}} 14:36:48.849 [main] INFO c.l.s.study.init.SimpleBeanProperty - propertyTest method is invoking.SimpleBeanProperty{simpleVariable='test567'}
从日志中可以看出bean在没有设置scope的时候,默认值为singletone的。另外即使属性类是protetype的时候,也会在父bean初始化将其填充。不会在调用父bean的时候,重新初始化属性所关联的bean。详细见例2
例2,在执行过程中,增加属性修改,咱们再来执行下看看
//修改property bean实例中的变量simpleVariable simpleBean.getProperty().setSimpleVariable("aaaaa"); //重新获取simpleBean实例 simpleBean = context .getBean("simpleBean", SimpleBean.class); //再次执行test方法 simpleBean.test();看下新增的日志:
15:14:58.447 [main] INFO c.l.spring.study.init.SimpleBean - SimpleBean is loading.SimpleBean{property=SimpleBeanProperty{simpleVariable='aaaaa'}} 15:14:58.447 [main] INFO c.l.s.study.init.SimpleBeanProperty - propertyTest method is invoking.SimpleBeanProperty{simpleVariable='aaaaa'}看来咱们之前的猜测是对的,
第一、bean的scope默认为SingleTone的
第二、bean的lazyInit为false的
第三、即使属性为prototype也不会再父bean为SingleTone的时重新初始化
例3、再增加两行
//获取property实例 SimpleBeanProperty property = context .getBean("property", SimpleBeanProperty.class); //测试propertyTest方法 property.propertyTest();
再看下执行后新增的日志:
15:19:10.331 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating instance of bean 'property' 15:19:10.331 [main] INFO c.l.s.study.init.SimpleBeanProperty - SimpleBeanProperty is loading. 15:19:10.331 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Finished creating instance of bean 'property' 15:19:10.331 [main] INFO c.l.s.study.init.SimpleBeanProperty - propertyTest method is invoking.SimpleBeanProperty{simpleVariable='test567'}
例4、再增加四行:
//获取anotherBean实例 SimpleAnotherBean anotherBean = context .getBean("anotherBean", SimpleAnotherBean.class); anotherBean.test(); //设置变量的值 anotherBean.setSimpleVariable("bbbbb"); //重新获取anotherBean实例 anotherBean = context .getBean("anotherBean", SimpleAnotherBean.class); anotherBean.test();
大家在看下执行日志:
15:23:13.130 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating instance of bean 'anotherBean' 15:23:13.130 [main] INFO c.l.s.study.init.SimpleBeanProperty - SimpleAnotherBean is loading. 15:23:13.130 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Finished creating instance of bean 'anotherBean' 15:23:13.130 [main] INFO c.l.s.study.init.SimpleBeanProperty - test method is invoking.SimpleAnotherBean{simpleVariable='test123'} 15:23:13.131 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating instance of bean 'anotherBean' 15:23:13.131 [main] INFO c.l.s.study.init.SimpleBeanProperty - SimpleAnotherBean is loading. 15:23:13.131 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Finished creating instance of bean 'anotherBean' 15:23:13.131 [main] INFO c.l.s.study.init.SimpleBeanProperty - test method is invoking.SimpleAnotherBean{simpleVariable='test123'}bean为prototype的时候,每次都会被新初始化的
通过日志的内容,梳理一下大概初始化逻辑
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