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Spring源码

流程图

一些基础类/接口

BeanFactory

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Bean 工厂实现应尽可能支持标准的 Bean 生命周期接口。完整的初始化方法集及其标准顺序为：
· BeanNameAware's setBeanName
· BeanClassLoaderAware's setBeanClassLoader
· BeanFactoryAware's setBeanFactory
· EnvironmentAware's setEnvironment
· EmbeddedValueResolverAware's setEmbeddedValueResolver
· ResourceLoaderAware's setResourceLoader (only applicable when running in an application context)
· ApplicationEventPublisherAware's setApplicationEventPublisher (only applicable when running in an application context)
· MessageSourceAware's setMessageSource (only applicable when running in an application context)
· ApplicationContextAware's setApplicationContext (only applicable when running in an application context)
· ServletContextAware's setServletContext (only applicable when running in a web application context)
· postProcessBeforeInitialization methods of BeanPostProcessors
· InitializingBean's afterPropertiesSet
· a custom init-method definition
· postProcessAfterInitialization methods of BeanPostProcessors

测试获取FactoryBean对象

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<bean class="cn.devnook.c1_entry.bean.User" name="user" init-method="initUser" factory-bean="userFactoryBean">
    <property name="name" value="Nook.Young"/>
    <property name="sex" value="女"/>
    <property name="age" value="18"/>
</bean>
<bean class="cn.devnook.c1_entry.bean.UserFactoryBean" name="userFactoryBean">
    <property name="createBy" value="Factory"/>
</bean>
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public class UserFactoryBean implements FactoryBean<User> {
    String createBy;

    public void setCreateBy(String createBy) {
        this.createBy = createBy;
    }

    @Override
    public User getObject()  {
        User user = new User();
        user.setCreateBy(createBy);
        return user;
    }

    @Override
    public Class<User> getObjectType() {
        return User.class;
    }

}
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public class C1_EntryTest {
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
        User user = ac.getBean("user", User.class);
        System.out.println(user);

        UserFactoryBean userFactoryBean = ac.getBean("&userFactoryBean", UserFactoryBean.class);
        System.out.println(userFactoryBean);
        User userFromFactory = userFactoryBean.getObject();
        System.out.println(userFromFactory.getCreateBy());

    }
}
  • BeanDefinition
  • BeanDefinitionReader
  • BeanFactoryPostProcessor
  • BeanPostProcessor
  • Environment
  • Aware

自定义扩展

1.校验启动参数 必须环境变量/启动参数 中必须有某个变量

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# 确定环境变量
echo $USER    

zy

假如必须校验环境变量中有USER变量:

自定义:MyClassPathXmlApplicationContext继承自ClassPathXmlApplicationContext

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public class MyClassPathXmlApplicationContext extends ClassPathXmlApplicationContext {

    public MyClassPathXmlApplicationContext(String... configLocations) {
        super(configLocations);
    }

    @Override
    protected void initPropertySources() {
        // 这里可以做一些自定义的操作
        // 比如：将配置文件中的属性值加密，然后再放入到环境变量中
        // 这样在后面的操作中，就可以直接使用加密后的属性值了
        // 这里就不做演示了

        System.out.println("自定义操作:>>>initPropertySources");
      	// 检验环境变量中的 USER
        getEnvironment().setRequiredProperties("USER");

        super.initPropertySources();
    }
}

单元测试:

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public class C2_MyClassPathXmlApplicationContextTest {
    public static void main(String[] args) {
        ApplicationContext ac = new MyClassPathXmlApplicationContext("spring-${USER}.xml");
        User user = ac.getBean("user", User.class);
        System.out.println(user);
    }
}

2.扩展实现customizeBeanFactory设置是否允许bbd重写以及循环依赖

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public class MyClassPathXmlApplicationContext extends ClassPathXmlApplicationContext {

    public MyClassPathXmlApplicationContext(String... configLocations) {
        super(configLocations);
    }

    @Override
    protected void customizeBeanFactory(DefaultListableBeanFactory beanFactory) {
    	  // 允许BBD重写
        super.setAllowBeanDefinitionOverriding(false);
      	// 允许循环依赖
        super.setAllowCircularReferences(false);
        super.customizeBeanFactory(beanFactory);
    }
}

3.配置自定义标签并让spring解析

主要步骤:

  1. 自定义对象,用于接受xml配置
  2. 自定义BeanDefinitionParser继承自AbstractSingleBeanDefinitionParser,重写getBeanClass(Element) 和 doParse(Element element, BeanDefinitionBuilder builder)
  3. 自定义NamespaceHandler 继承自 NamespaceHandlerSupport,重写init()
  4. 自定义spring.handlers配置
  5. 自定义spring.schemas
  6. 自定义xsd文件

自定义对象:DevNook

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package cn.devnook.c1_entry.selftag;

public class DevNook {
    private String username;
    private String email;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "DevNook{" +
                "username='" + username + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

自定义parser

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package cn.devnook.c1_entry.selftag;


import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
import org.springframework.util.StringUtils;
import org.w3c.dom.Element;

public class DevNookBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {

    @Override
    protected Class<?> getBeanClass(Element element) {
        return DevNook.class;
    }

    @Override
    protected void doParse(Element element, BeanDefinitionBuilder builder) {
        String username = element.getAttribute("username");
        String email = element.getAttribute("email");
        if(StringUtils.hasText(username)){
            builder.addPropertyValue("username", username);
        }
        if(StringUtils.hasText(email)){
            builder.addPropertyValue("email", email);
        }

    }
}

自定义handler

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package cn.devnook.c1_entry.selftag;

import org.springframework.beans.factory.xml.NamespaceHandlerSupport;

public class DevNookNamespaceHandler extends NamespaceHandlerSupport {
    @Override
    public void init() {
        registerBeanDefinitionParser("user", new DevNookBeanDefinitionParser());
    }
}

META-INF/spring.handlers

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http\://www.devnook.cn/schema/devnook=cn.devnook.c1_entry.selftag.DevNookNamespaceHandler

META-INF/spring.schemas

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http\://www.devnook.cn/schema/devnook=cn.devnook.c1_entry.selftag.DevNookNamespaceHandler

META-INF/devnook.xsd

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<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
        targetNamespace="http://www.devnook.cn/schema/devnook"
        elementFormDefault="qualified">
    <element name="user">
        <complexType>
            <attribute name="id" type="string"/>
            <attribute name="username" type="string"/>
            <attribute name="email" type="string"/>
        </complexType>
    </element>
</schema>

spring主配置文件:selftag.xml 

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:devnook="http://www.devnook.cn/schema/devnook"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       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.devnook.cn/schema/devnook http://www.devnook.cn/schema/devnook.xsd">
    <devnook:user id="devnook" username="devnook@user" email="[email protected]"/>
</beans>

入口程序: SelfTagTest

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package cn.devnook.c1_entry.selftag;

import cn.devnook.c1_entry.bean.MyClassPathXmlApplicationContext;
import cn.devnook.c1_entry.bean.User;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SelfTagTest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("selftag.xml");
        DevNook devnook = ac.getBean("devnook", DevNook.class);
        System.out.println(devnook);

        ac.close();
    }
}

4.拓展自定义属性编辑器

  1. 自定义属性编辑器 AccountEditor 实现PropertyEditorSupport
  2. 自定义属性注册器xxxEditorRegistrar 实现PropertyEditorRegistrar
  3. 自定义 AccountEditorConfigurer 继承自 CustomEditorConfigurer 并交由spring管理(在xml声明)
    Account
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package cn.devnook.c1_entry.selfeditor;

@Data
public class Account {
    private Integer id;

    private String name;

    private AccountAddress address;
}

AccountAddress

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package cn.devnook.c1_entry.selfeditor;

@Data
public class AccountAddress {
    private String province;
    private String city;
 }

自定义属性编辑器 AccountEditor

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package cn.devnook.c1_entry.selfeditor;

import java.beans.PropertyEditorSupport;

public class AccountEditor extends PropertyEditorSupport {
    @Override
    public void setAsText(String text) throws IllegalArgumentException {
        String [] arr = text.split("_");
        AccountAddress address = new AccountAddress();
        address.setProvince(arr[0]);
        address.setCity(arr[1]);
        this.setValue(address);
    }
}

自定义注册器 AccountEditorRegistrar

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package cn.devnook.c1_entry.selfeditor;

import org.springframework.beans.PropertyEditorRegistrar;
import org.springframework.beans.PropertyEditorRegistry;

public class AccountEditorRegistrar implements PropertyEditorRegistrar {
    @Override
    public void registerCustomEditors(PropertyEditorRegistry registry) {
        registry.registerCustomEditor(AccountAddress.class, new AccountEditor());
    }

}

自定义配置类:AccountEditorConfigurer

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package cn.devnook.c1_entry.selfeditor;

import org.springframework.beans.factory.config.CustomEditorConfigurer;

public class AccountEditorConfigurer extends CustomEditorConfigurer {



}

spring主配置文件:selfeditor.xml

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:util="http://www.springframework.org/schema/util"
       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/util https://www.springframework.org/schema/util/spring-util.xsd">
    <bean id="account" class="cn.devnook.c1_entry.selfeditor.Account">
        <property name="id" value="1"></property>
        <property name="name" value="devnook"></property>
        <property name="address" value="上海_闵行"></property>
    </bean>

    <bean class="cn.devnook.c1_entry.selfeditor.AccountEditorConfigurer">
        <property name="propertyEditorRegistrars">
            <array>
                <bean class="cn.devnook.c1_entry.selfeditor.AccountEditorRegistrar"></bean>
            </array>
        </property>
    </bean>
</beans>

入口程序: SelfEditorTest

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package cn.devnook.c1_entry.selfeditor;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SelfEditorTest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("selfeditor.xml");
        Account account = ac.getBean("account", Account.class);
        System.out.println(account);
    }
}

运行结果:

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Account{id=1, name='devnook', address=AccountAddress{province='上海', city='闵行'}}

从xml加载BeannDefinition到DefaultListableBeanFactory

Q:

  1. prepareRefresh()中 earlyApplicationListeners 和 applicationListeners 作用

  2. obtainFreshBeanFactory 时候为什么需要先refreshBeanFactory

  3. [AbstractRefreshableApplicationContext] allowBeanDefinitionOverriding allowCircularReferences

org.springframework.context.support.AbstractApplicationContext#refresh

许可协议

本文采用 署名-非商业性使用-相同方式共享 4.0 国际 许可协议，转载请注明出处。